ALBERT

Description: The scientific requirements and implications for the instruments and telescope design for the Next Generation Space Telescope (NGST) are described. A candidate concept is a deployable, 8 m diameter telescope, optimized for the near infrared region, but featuring instruments capable of observing up to 30 micrometers. The observatory is radiatively cooled to approximately 30 K.

Description: Detailed understanding of the properties of the point-spread function (PSF) of Space Telescope Imaging Spectrograph (STIS) imaging modes is necessary to separate real effects of geometrically complex astronomical sources, such as protoplanetary disks surrounding bright stars, from instrumental effects, such as scattering and diffraction. In order to investigate STIS imaging properties we have numerically simulated broadband stellar PSFs generated by STIS in CCD clear imaging mode, including the effects of the Lyot stop and the coronagraphic wedges. The input spectrum is a stellar model atmosphere of the appropriate spectral type, convolved with the pre-flight STIS CCD response function. The PSF modeler generates broadband PSFs by co-adding weighted monochromatic PSFs across the waveband.

Description: Using the Early Release Observation of 9 Comae, we demonstrate an iterative method for correcting Space Telescope Imaging Spectrograph (STIS) echelle spectra for the effects of the echelle ripple. This analytic approach allows the actual spectrum of interest to be used in the determination of its calibration. The late F star 9 Comae is not an ideal candidate for this method, due to the many absorption lines present in its E230M spectrum, yet, given this difficulty, the method still works quite well.

Description: The installation of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) allows for the first time two-dimensional optical and ultraviolet slitless spectroscopy of faint objects from space. The STIS Parallel Survey (SPS) routinely obtains broad band images and slitless spectra of random fields in parallel with HST observations using other instruments. The SPS is designed to study a wide variety of astrophysical phenomena, including the rate of star formation in galaxies at intermediate to high redshift through the detection of emission-line galaxies. We present the first results of the SPS, which demonstrate the capability of STIS slitless spectroscopy to detect and identify high-redshift galaxies.

Description: An analysis of the fine pointing errors of the Hubble Space Telescope (HST), in the range from 1 to 15 milliarcsecs, is reported on. The emphasis is on the study of the performance characteristics of the pointing control system, fine guidance sensors and the optical telescope assembly, which produce relative attitude and astrometric measurement errors. Since the first servicing mission in December 1993, the HST relative short term position stability is of the order of 3 milliarcsecs RMS when averaged over 1 min intervals. At this level of accuracy, longer term systematic attitude errors in this range can have a noticeable impact on the telescope's observations. The various error sources are described, including: internal temperature effects; spacecraft structure temperature effects; calibration procedures, and computational inaccuracies.

Description: The prospects for global astrometric measurements with the space interferometry mission (SIM) are discussed. The SIM mission will perform four microarcsec astrometric measurements on objects as faint as 20 mag using the optical interferometry technique with a 10 m baseline. The SIM satellite will perform narrow angle astrometry and global astrometry by means of an astrometric grid. The sensitivities of the SIM global astrometric performance and the grid accuracy versus instrumental parameters and sky coverage schemes are reported on. The problems in finding suitable astrometric grid objects to support microarcsec astrometry, and related ground-based observation programs are discussed.

Description: The space interferometry mission (SIM), for launch in 2004, is expected to determine the positions of point sources to a global accuracy of 4 microarcsec, and an accuracy of 1 microarcsec over small angles. The instrument will reach 200 mag in 3 x 10(exp 4) s and has a nominal lifetime of five years. A nulling capability will be provided and synthesis imaging and near-infrared capabilities are being considered. These capabilities will extend those of the Hipparcos mission by almost three orders of magnitude in every sense. The NASA's expectation for the scientific return from the SIM mission is outlined in terms of the areas of stellar physics, galactic structure and extragalactic astrophysics, including the distance scale problem.

Description: The burst and transient source experiment (BATSE) survey of the high energy emission from supernova remnants is reported on. The ability of BATSE to continuously monitor the entire sky in the 20 keV to 2 MeV energy range enables a large group of remnants to by studied at high energies. Preliminary analysis indicates the likely detection of several supernova remnants other than the Crab nebula. Among these are MSH 15-52, Vela, Cas A and possibly HB 9. The techniques employed are discussed together with the status of the survey and its limitations.

Description: Data from the transient gamma ray germanium detector taken during 1995 provide a limited ability to study the high resolution spectrum of the X-ray transient GRO J1655-40. During a two-day period around the peak intensity, the soft spectrum was measured and found to be consistent with a power law spectrum with photon index -3.0 +/- 0.2. No evidence was found for narrow spectral features in the 50 to 100 keV band or around 511 keV. The 3 sigma upper limit for a narrow emission line at 511 keV is 1.2 x 10(exp -2) phot/cu cm s.

Description: We describe the STIS autonomous target acquisition capabilities. We also present the results of dedicated tests executed as part of Cycle 7 calibration, following post-launch improvements to the Space Telescope Imaging Spectrograph (STIS) flight software. The residual pointing error from the acquisitions are 〈 0.5 CCD pixels, which is better than preflight estimates. Execution of peakups show clear improvement of target centering for slits of width 0.1 sec or smaller. These results may be used by Guest Observers in planning target acquisitions for their STIS programs.

Description: Various tests have been done of the Space Telescope Imaging Spectrograph (STIS) using internal wavecals to measure thermal motion of the spectral format on the detectors. In most cases, the spectral format moves less than the specification not to exceed 0.2 pixels per hour. Primary causes of the motion are (1) changes to the thermal design dictated by the warmer Aft Shroud environment and (2) on-orbit power cycling of Multi-Anode Microchannel Arrays (MAMA) electronics to minimize the effects of radiation hits on the MAMA detectors. The rear portion of the STIS optical bench is too warm to be held at a constant temperature by internal heaters. Electronics swing in temperature with an orbital and daily frequency. The thermal drift of the optical formats is not negligible, but is well behaved in most circumstances. The observer is advised to examine the trade-off between the most accurate wavelengths with best spectral/spatial resolutions versus increased overheads that directly affect the observing times. A long term concern is that the Aft Shroud thermal environment is predicted to heat up as much as one Centigrade degree per year. Progressively more of the bench would move out of thermal control. Thus the external cooler for STIS, being considered for the Third Servicing Mission is of major importance to the long term operation of STIS.

Description: The astrophysical implications of the large width of the 1809 keV gamma ray line from the decay of radioactive Al-26, recently observed with the gamma ray imaging spectrometer (GRIS), are discussed. While there may be no apparent single mechanism that can explain the observed broadening, high speed dust grains, extremely hot superbubbles and a large, low density gaseous halo were identified in the Galactic center region as the possible origins. The implications of these observations on the hot gas content in the interstellar medium are discussed.

Description: The phenomenon of broad gamma ray line splitting is discussed, together with a scenario for the suppression of the blue wings of these broad lines due to the geometry of the accelerated particle interaction region. The broad and narrow gamma ray line emissions are compared taking into account the line splitting effect. It is concluded that the observed gamma ray lines from Orion are most likely broad, implying that the low energy cosmic rays which produce this line emission consist mostly of C and heavier ions. The suppression of the proton and alpha particle abundances requires acceleration conditions such as the acceleration of the ejecta of the supernovae before mixing with the interstellar medium. Similar conditions are implied by observations of the B and Be in low metallicity stars formed during the first Gyr of galactic evolution.

Description: It is proposed to use data from the burst and transient source experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO) as a sensitive, rapid, all sky monitor for the International Gamma Ray Astrophysics Laboratory (INTEGRAL). The all sky earth occultation monitoring and imaging capabilities of BATSE will complement and extend the Galactic plane scans of INTEGRAL as well as provide high latitude Galactic coverage which is inaccessible to INTEGRAL. Examples of transients previously observed by BATSE, its sensitivity, and the response time for these observations are described. Examples of the variability of several of the brighter sources observed by BATSE are shown.

Description: The spectrometer for INTEGRAL (SPI) is a germanium spectrometer with a wide field of view and will provide the International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission with the opportunity of studying gamma ray bursts. Simulations carried out to assess the response of the instrument using data from real burst data as input are reported on. It is shown that, despite the angular resolution of 3 deg, it is possible to locate the direction of bursts with an accuracy of a few arcmin, while offering the high spectral resolution of the germanium detectors. It is remarked that the SPI field of view is similar to the size of the halo of bursts expected around M 31 on galactic models. The detectability of bursts with such a halo is discussed.

Description: The results from observations of a sample of BL Lac objects by the Compton telescope (COMPTEL) and energetic gamma ray experiment telescope (EGRET) onboard the Compton Gamma Ray Observatory (CGRO) are presented. The main targets in the sample were selected on the basis of their X-ray brightness and apparent spectral hardening at hard X-ray energies. One of the targets, PKS 0521-365 was detected by EGRET, and these data are presented together with contemporaneous ground-based radio data. Subsequent X-ray observations of this source with the Advanced Satellite for Cosomology and Astrophysics (ASCA) demonstrated that, although originally classified as a BL Lac object, it is better described as a flat spectrum radio quasar. Upper limits on the gamma ray flux from all the non-detected BL lacs are presented.

Description: Observations of the Galactic black hole candidate binary system GX 339-4 at radio, optical and X-ray wavelengths are reviewed. The radio observations reveal a compact, persistent and variable source. On the average, the radio intensity is less than 10 mJy. These data, when compared with previous data, indicate no set correlation between the radio and X-ray emission. The X-ray intensity suggests a 14.5 month cycle. The latest radio observational data are presented together with X-ray data and are discussed in the context of similar correlated observations from other X-ray binaries.

Description: The hard X-ray behavior of several X-ray binary systems containing a neutron star or a black hole candidate is analyzed in an attempt to determine the specific signature of these categories of compact objects. Limiting the consideration to two subclasses of neutron stars, Atoll sources and non-pulsating Z sources, it appears that only the Atoll sources have a spectral behavior similar to black holes. It is proposed that Atoll sources are weakly magnetized neutron stars, whereas Z sources are small radius moderate magnetized neutron stars. Large magnetic fields funnel the accreting matter, thus preventing spherical accretion and free fall if the neutron star radius is smaller than the last stable accreting orbit. Weak magnetic fields do not have this effect, and blackbody soft photons from the stellar surface are upscattered on the relativistic infalling matter, leading to excess hard X-rays. This excess is visible in two of the observed Atoll sources and in the spectrum of a black hole candidate. In the case of a Z source, a lack of photons was remarked, providing a possible signature to distinguish between these classes of objects.

Description: The submillimeter wave astronomy satellite (SWAS) mission is dedicated to the investigation of star formation and interstellar chemistry. In order to perform the mission, SWAS will survey dense molecular clouds within the Milky Way Galaxy in either the ground state or a low-lying transition of five astrophysically-significant species: H2O, H2(18)O, O2, C I and (13)CO. The observation of these lines will: test theories that predict that these species are dominant coolants of molecular clouds during early stages of their collapse to form stars and planets, and supply information concerning the abundance of species central to the chemical models of dense interstellar gas. The SWAS will use two independent Schottky barrier diode mixers and a 53 x 68 sq cm, off-axis Cassegrain antenna.

Description: Dramatic torque reversals between spin-up and spin-down have been observed in half of the persistent X-ray pulsars monitored by the Burst and Transient Space Experiment (BATSE) all-sky monitor on the Compton Gamma Ray Observatory. Theoretical models developed to explain early pulsar timing data can explain spin-down torques via a disk-magnetosphere interaction if the star nearly corotates with the inner accretion disk. To produce the observed BATSE torque reversals, however, these equilibrium models require the disk to alternate between two mass accretion rates, with M+/- producing accretion torques of similar magnitude but always of opposite sign. Moreover, in at least one pulsar (GX 1+4) undergoing secular spin-down, the neutron star spins down faster during brief (approximately 20 day) hard X-ray flares-this is opposite the correlation expected from standard theory, assuming that BATSE pulsed flux increases with mass accretion rate. The 10 day to 10 yr intervals between torque reversals in these systems are much longer than any characteristic magnetic or viscous timescale near the inner disk boundary and are more suggestive of a global disk phenomenon. We discuss possible explanations of the observed torque behavior. Despite the preferred sense of rotation defined by the binary orbit, the BATSE observations are surprisingly consistent with an earlier suggestion for GX 1+4: the disks in these systems somehow alternate between episodes of prograde and retrograde rotation. We are unaware of any mechanism that could produce a stable retrograde disk in a binary undergoing Roche lobe overflow, but such flip-flop behavior does occur in numerical simulations of wind-fed systems. One possibility is that the disks in some of these binaries are fed by an X-ray-excited wind.

Description: The HTXS mission concept combines large effective area (approximately 15,000 sq cm at 1 keV), high spectral resolution (E/Delta(E) approximately 300-3000), and broad energy bandpass (0.25-40 keV and possibly up to 100 keV) by using replicated optics together with a complement of spectroscopic instrumentation including reflection gratings readout by charge-coupled device detectors (CCDs), quantum micro-calorimeters, and cadmium zinc telluride (CZT) or comparable high energy detectors. An essential feature of this concept involves minimization of cost (approximately $350M for development and approximately $500-600M including launches) and risk by building six identical modest satellites to achieve the large area. Current mission and technology studies are targeted towards a new start in the 2002 timeframe, with first launch around 2005-2006. The HTXS mission represents a major advance, providing as much as a factor of 100 increase in sensitivity over currently planned high resolution X ray spectroscopy missions. HTXS will mark the start of a new era when high quality X ray spectra will be obtained for all classes of X ray sources, over a wide range of luminosity and distance. With its increased capabilities, HTXS will address many fundamental astrophysics questions such as the origin and distribution of the elements from carbon to zinc, the formation and evolution of clusters of galaxies, the validity of general relativity in the strong gravity limit, the evolution of supermassive black holes in active galactic nuclei, the details of supernova explosions and their aftermath, and the mechanisms involved in the heating of stellar coronae and driving of stellar winds.

Description: From a sample of 7 MSFC vector magnetograms,of active regions and 17 Yohkoh SXT soft X-ray images of these active regions, we have found that the total x-ray brightness of an entire active region is correlated with the total length of neutral lines on which the magnetic field is both strong (less than 250 G) and strongly sheared (shear angle greater than 75 deg) in the same active region. This correlation, if not fortuitous, is additional evidence of the importance of strong-shear strong-field neutral lines to strong heating in active regions.

Description: This rapporteur contribution attempts to summarize the discussions at this conference in the context of current funding realities.

Description: We present the results of timing and spectral studies of the dipping X-ray source X1916-053, observed by ASCA during its Performance Verification phase. The detected dipping activity is consistent with previous observations, with a period of 3008s and an intermittent secondary dip observed roughly 0.4 out of phase with the primary dip. The energy spectra of different intensity states are fitted with a power law with partial covering fraction absorption and interstellar absorption. The increase in the hardness ratio during the primary and secondary dips, and the increase in the covering fraction and column density with decreasing X-ray intensity, all imply that the dipping is caused by the photo-absorbing materials which have been suggested to be where the accreted flow hits the outer edge of the disk materials. The spectra at all intensity levels show no apparent evidence for Fe or Ne emission lines. This may be due to the low metal abundance in the accretion flow. Alternatively, the X-ray luminosity of the central source may be too weak to excite emission lines, which are assumed to be produced by X-ray photoionization of the disk materials.

Description: We report submilliarsecond-precise astrometric measurement for the late-type star AB Doradus via a combination of VLBI (very long baseline interferometry) and Hipparos satellite data. Our astrometric analysis results in the precise determination of the kinematics of this star, that reveals an orbital motion readily explained as caused by the gravitational interaction with a low-mass companion.

Description: We present 8-13 mue spectra of 23 young Stars acquired with the UKIRT CGS3 spectrometer, including T Tauri, Herbig Ae/Be, and FU Ori Stars.

Description: We presen 8-13 meu spectra of 23 young stars acquired with the UKIRT CGS3 spectromere, including T Tauri, Herbig Ae/Be, and FU Ori stars. Silicate emission and absorption features can generally be matched with the Trapezium emissivity, by employing simple models to account for optical depth effects.

Description: The illuminating source of the photodissociation region associated with the reflection nebula NGC7023 is HD200775. We probed the foreground atomic and molecular material through diagnostics observed in absorption against the background star.

Description: Recent spectral observations of asteriods have identified a plausible origin for the ordinary chondrite meteorites (OCs). Owing to the paucity of main-belt asteriods with matching spectra [1], it had previously been difficult to explain their origin.

Description: In this paper, a pointing control performance criteria is established to suppport high resolution space spectroscopy. Results indicate that these pointing control requirements are very stringent, and would typically be difficult to meet using standard 3-axis spacecraft control. To resolve this difficulty, it is shown that performance can be significantly improved using a reconfigurable control architecture that switches among a small bankof detuned Kalman filters. The effectiveness of the control reconfiguration approach is demonstrated by example on the Space Infra-Red Telescope Facility (SIRTF) pointing system, in support of the InfraRed Spectrograph (IRS) payload.

Description: For this effort we requested ROSAT images of two small gamma-ray burst (GRB) error boxes. Our goal was to search for sources that might be associated with the quiescent site of a GRB. More than 1000 GRBs have been detected in the twenty five years since their discovery, yet their origin remains a mystery. No real-time or quiescent counterparts at any wavelength have been identified as sources of GRBs despite considerable follow-up efforts. Ground based campaigns to examine GRB error boxes shortly after the bursts have revealed no transient, or highly variable objects at optical and radio wavelengths in the time period of more than 7 hours after the burst. Due to the heavy demand on X-ray satellite time, and the difficulty of re-scheduling observations, rapid follow-up observations at high energies have not been obtained as quickly as the ground based-efforts. In fact, X-ray images of GRB error boxes are normally obtained months-years after burst detection. The current fastest X-ray response time is over two weeks. Deep imaging of GRB error boxes at X-ray wavelengths is an additional observational approach that can be used to constrain models of the origin of GRBs. We combined the results of our investigation of the GRB920525 error box with that of a prior ROSAT PSPC observation of GRB910814 and submitted them for publication. We conclude that based upon our efforts and those of others, deep X-ray observations obtained long after the GRB are not likely to yield further productive results until smaller GRB error boxes become available. It may be possible to obtain such small error boxes in the near future from XTE, HETE and an augmented IPN.

Description: The results of oriented scintillation spectrometer experiment (OSSE) observations of the ultraluminous infrared galaxies Arp 220 and Mrk 273 are reported. The pointings of Arp 220 and Mrk 273 concentrated on their upper limits. The gamma ray luminosities from these sources were found to be between one and two orders of magnitude smaller than the infrared luminosities. Multiwavelength luminosity spectra are produced from the radio to the gamma ray regime, and are compared with the typical multiwavelength spectra of active galactic nuclei. The lack of measured gamma ray emission provides no evidence for the existence of buried active galactic nuclei in these ultraluminous infrared galaxies, but is consistent with an origin of the infrared luminosity from starburst activity.

Description: The Rossi X-ray Timing Explorer (RXTE) observed three active galaxies during its in-orbit verification phase: NGC 4151; NGC 4945, and MCG 8-11-11. All three were detected from 2 keV to more than 100 keV by a combination of the proportional counter array (PCA) and the high energy X-ray timing experiment (HEXTE). The PCA contains five, xenon/methane, multilayer, multiwire, gas proportional counters covering the 2 to 60 keV range, while HEXTE is an array of eight NaI/CsI phoswich scintillation counters covering the 15 to 250 keV range. The three active galaxies represent the classes of Seyfert 1, Seyfert 2 and intermediate Seyfert galaxies. The results of the fitting of various models containing partial covering fractions, Compton reflection components and high energy spectral breaks are discussed.

Description: The Compton telescope (COMPTEL) onboard the Compton Gamma Ray Observatory (CGRO) detected the pulsar PSR B1951-32 at MeV energies, and found indications of a signal from PSR B0656+14. In the combined spectra from COMPTEL and the energetic gamma ray experiment telescope (EGRET) onboard CGRO, it can be seen that the maximum luminosities of these objects are reached in the COMPTEL energy range. These spectra can be compared with those from four other pulsars observed in MeV energies with COMPTEL. The spectral properties of five of the six pulsars, Vela, PSR B1509-58, PSR B1951-32 and PSR B0656+14, require breaks and bends at MeV energies. The sixth pulsar, the Crab pulsar, approximately follows a power law flux relation from keV to GeV energies. It is concluded that this spectral behavior may play a role in the discrimination between current gamma ray emission models.

Description: Observations of the 511 keV emission in the direction of 1E 1740.7-2942 (1E) using the earth burst and transient source experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO), are presented. The CGRO phase 1 average spectrum of 1E is calculated using a method which assumes that a given source spectrum is the sum of the flux coming directly from the object and the contribution from the surrounding diffuse emission. The 1E light curve is calculated in the 40 to 150 keV range. It presents a constant flux excess of 70 mCrab in comparison with observations from the SIGMA gamma ray telescope onboard the GRANAT observatory. By removing this contribution, the 1E spectral transition from the low state to the high standard state observed by SIGMA is confirmed, and it is shown that the 511 keV flux is independent of the 1E long term evolution from low state to high standard state. It is concluded that the 511 keV emission of (4.2 +/- 1.3) x 140(exp -4) photons/sq cm s observed in the direction of 1E is mainly diffuse and spatially extended.

Description: We report on the observation of the HI filament LVC 88+36-2 with the Deep Survey/Spectrometers of EUVE. Detecting the shadow of this cloud in absorption might have proven the existence of a diffuse EUV background behind the cloud, and constrain the emission geometries of the hot plasma in the Local Interstellar Medium (LISM). By detecting diffuse emission in the EUVE spectrometers, it would also be possible to constrain the temperature and pressure of the emitting regions as well as determine whether or not the hot phase of the LISM is in equilibrium with cosmic elemental abundances. Unfortunately, we did not detect a cloud shadow with this set of observations. This is due to a combination of circumstances, but mostly due to the fact that EUV diffuse emission is weak compared to the background levels of EUVE. If a shadow exists in the EUVE, then it is less than 1% of the EUVE detector background of 1e-3 cts arcmin(exp -2) in the Deep Survey detector.

Description: We present the results of an HST and ground-based imaging study of a complete 3C sample of zeta approx. equal to 1 sources, comprising 5 quasars and 5 radio galaxies. We have observed all of the sample in essentially line-free bands at rest-frame 0.33 micrometers with WFPC2 and in rest-frame 1 micrometer images from the ground; we have also observed most of the sample in narrow-band filters centered on [O II]. We resolve continuum structure around all of our quasars in the high-resolution WFPC2 images, and in four of the five ground-based K' images. All of the quasars have some optical continuum structure that is aligned with the radio axis. In at least 3 of these cases, some of this optical structure is directly coincident with a portion of the radio structure, including optical counterparts to radio jets in 3C212 and 3C245 and an optical counterpart to a radio lobe in 3C2. These are most likely due to optical synchrotron radiation, and the radio and optical spectral indices in the northern lobe of 3C2 are consistent with this interpretation. The fact that we see a beamed optical synchotron component in the quasars but not in the radio galaxies complicates both the magnitude and the alignment comparisons. Nonetheless, the total optical and K' flux densities of the quasar hosts are consistent with those of the radio galaxies within the observed dispersion in our sample. The distributions of K' flux densities of both radio galaxies and quasar hosts exhibit similar mean and dispersion to that found for other radio galaxies at this redshift, and the average host galaxy luminosity is equivalent to, or a little fainter than, L*. The formal determination of the alignment in the optical and infrared in the two subsamples yields no significant difference between the radio galaxy and quasar subsamples, and the quasars 3C 196 and 3C 336 have aligned continuum and emission-line structure that is probably not due to beamed optical synchrotron emission. Very blue and/or edge-brightened structures are present in some objects within the probable quasar opening angle; these are possibly the result of illumination effects from the active nucleus, i.e., scattered quasar light or photoionization. In 3C 212, we see an optical object that lies 3 min. beyond the radio lobe, but which looks morphologically quite similar to the radio lobe itself. This object is bright in the infrared and has a steep spectral gradient along its length. A striking, semi-circular arc seen associated with 3C 280 may possibly be a tidal tail from a companion, enhanced in brightness by scattering or photoionization. In the near-infrared, most of the radio galaxies have elliptical morphologies with profiles that are well-fit by de Vaucouleurs r(exp 1/4)-laws and colors that are consistent with an old stellar population. All components around the quasars have optical-infrared colors that are redder than or similar to the colors of their respective nuclei; this is more consistent with a stellar origin for the emission than with a dominant scattering contribution. From the correspondence between the total magnitudes in the galaxies and quasars and the detection of aligned components in the quasars, we conclude that this study provides general support for the unification of FR II radio galaxies and quasars. Some of the objects in the sample (e.g, 3C 212) have properties that may be difficult to explain with our current understanding of the nature of FR II radio sources and the alignment effect.

Description: Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here preliminary results from a multi-wavelength campaign undertaken from July to September 1996. This study includes X-ray data from the RXTE All Sky Monitor and BATSE, two-frequency data from the Nancay radio telescope, and infrared photometry from the 1.8m Perkins telescope at Lowell Observatory. The K-band data presented herein provide the first long-term well-sampled IR light curve of GRS 1915+105. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities.

Description: This is a continuing program to extend and refine the ephemeris of the Geminga pulsar with annual observations for the remaining lifetime of EGRET. The data show that every revolution of Geminga is accounted for during the EGRET epoch, and that a coherent timing solution linking the phase between EGRET, COS-B, amd SAS-2, observations has now been achieved. The accuracy of the gamma-ray timing is such that the proper motion of the pulsar can now be detected, consistent with the optical determination. The measured braking index over the 24.2 yr baseline is 17 +/- 1. Further observation is required to ascertain whether this very large braking index truly represents the energy loss mechanism, perhaps related to the theory in which Geminga is near its gamma-ray death line, or whether it is a manifestation of timing noise. Statistically significant timing residuals are detected in the EGRET data; they depart from the cubic ephemeris at a level of 23 milliperiods. The residuals appear to have a sinusoidal modulation with a period of about 5.1 yr. This could simply be a manifestation of timing noise, or it could be consistent with a planet of mass 1.7/sin i solar mass orbiting Geminga at a radius of 3.3/sin i AU.

Description: The motivation for this work came from a NASA Headquarters interest in investigating design concepts for a large space telescope employing active optics technology. The development of telescope optical requirements and potential optical design configurations is reported.

Description: The transient black hole candidate GRO J1655-40 was shown elsewhere to eject matter at apparently superluminal velocities. The oriented scintillation spectrometer experiment (OSSE) spectra, measured during the X-ray outbursts, are consistent with a single power law up to 600 keV, with no evidence of a high energy cutoff. The detection of the flaring behavior of this source up to 10 MeV was claimed elsewhere. The Compton telescope (COMPTEL) observations in the 0.75 to 30 MeV band of this source are analyzed. The upper limits on the time averaged emission are presented and gamma ray flares are searched for. It is concluded that the COMPTEL data can neither confirm nor refute the claimed detection of a large gamma ray flare from this source. The gamma ray flare search in five years' worth of data did not reveal evidence for the occurrence of strong flares on timescales of two days.

Description: Soft gamma ray repeaters appear to be a new class of neutron stars. While a counterpart to SGR 0525-66 was detected uniquely in the X-ray band, SGR 1806-20 and SGR 1900+14 have unusual stellar counterparts whose spectra peak in the infrared. The infrared spectra appear to contain several components: the photospheric emission from stars dominates at shorter wavelengths; a bright point source dominates at 25 micrometers, and an extended source dominates at 60 micrometers. The longer wavelength spectra are inconsistent with mono-energetic synchrotron and black body radiation models. Recent millimeter, submillimeter and infrared observations are reviewed. A preliminary analysis of the higher resolution infrared spectra of SGR 1806-20 and SGR 1900+14 is outlined. These confirm previous observations suggesting that SGR1806-20 has an outflow and that the stars comprising the counterpart to SGR 1900+14 have very similar spectra.

Description: Results from recent observations of the Orion/Monoceros region, acquired with the Compton telescope (COMPTEL), are summarized, confirming previously reported results of excessive 3 to 7 MeV emission which is probably due to nuclear de-excitation lines from C-12 and O-16 nuclei following energetic nuclear interactions. The emphasis is on findings concerning the extent of the emission region. It is found that the emission extends over the entire cloud complex, although it may result from a few localized source regions. A preliminary spectrum is presented which indicates that the emission is widely spread over the 3 to 7 MeV range, suggesting a dominantly broadline origin from energetic C and O nuclei. The spectrum shows features that may be due to the splitting of the C and O lines.

Description: On 1999 August 11, a total eclipse of the Sun will be visible from within a narrow corridor which traverses the Eastern Hemisphere. The path of the Moon's umbral shadow begins in the Atlantic and crosses central Europe, the Middle East, and India, where it ends at sunset in the Bay of Bengal. A partial eclipse will be seen within the much broader path of the Moon's penumbral shadow, which includes northeastern North America, all of Europe, northern Africa, and the western half of Asia. Detailed predictions for this event are presented and include besselian elements, geographic coordinates of the path of totality, physical ephemeris of the umbra, topocentric limb profile corrections, local circumstances for approximately 1400 cities, maps of the eclipse path, weather prospects, the lunar limb profile, and the sky during totality. Tips and suggestions are also given on how to safely view and photograph the eclipse.

Description: We analyze the spatial clustering properties of a new catalog of very rich galaxy clusters selected from the APM Galaxy Survey. These clusters are of comparable richness and space density to Abell Richness Class greater than or equal to 1 clusters, but selected using an objective algorithm from a catalog demonstrably free of artificial inhomogeneities. Evaluation of the two-point correlation function xi(sub cc)(r) for the full sample and for richer subsamples reveals that the correlation amplitude is consistent with that measured for lower richness APM clusters and X-ray selected clusters. We apply a maximum likelihood estimator to find the best fitting slope and amplitude of a power law fit to x(sub cc)(r), and to estimate the correlation length r(sub 0) (the value of r at which xi(sub cc)(r) is equal to unity). For clusters with a mean space density of 1.6 x 10(exp -6) h(exp 3) MpC(exp -3) (equivalent to the space density of Abell Richness greater than or equal to 2 clusters), we find r(sub 0) = 21.3(+11.1/-9.3) h(exp -1) Mpc (95% confidence limits). This is consistent with the weak richness dependence of xi(sub cc)(r) expected in Gaussian models of structure formation. In particular, the amplitude of xi(sub cc)(r) at all richnesses matches that of xi(sub cc)(r) for clusters selected in N-Body simulations of a low density Cold Dark Matter model.

Description: This grant was in support of a guest observation using the ASCA satellite of the young, spin-powered pulsar PSR B1706-44. The pulsar is interesting for several reasons: 1) it is young and shares many similar characteristics with the Vela pulsar, 2) it is one of a few pulsars which has been detected by the EGRET detector aboard the CGRO satellite, and 3) it is one of the confirmed sources of TeV gamma-rays discovered with ground based telescopes. The goals of the observation were to search for pulsations in the X-ray domain and to study the near stellar environment to determine if the pulsar is embedded within a compact nebula as in the case of the Vela pulsar.

Description: We present GHRS/HST observations of the RS CVn binary system HD 155555. Several key UV emission lines (Fe XXI, Si IV, O V, C IV) have been analyzed to provide information about the heating rate throughout the atmosphere from the chromosphere to the corona. We show that both the G and K components reveal features of a chromosphere, transition region and corona. The emission measure distribution as a function of temperature for both components is derived and compared with the RS Cvn system, HR 1099, and the Sun. The transition region and coronal lines of both stars show nonthermal broadenings of approx. 20-30 km/s. Possible physical implications for coronal heating mechanisms are discussed.

Description: With the support of NASA's Astrophysics Data Program (NRA 92-OSSA-15), we have developed the Astronomical Software Directory Service (ASDS): a distributed, searchable, WWW-based database of software packages and their related documentation. ASDS provides integrated access to 56 astronomical software packages, with more than 16,000 URLs indexed for full-text searching. Users are performing about 400 searches per month. A new aspect of our service is the inclusion of telescope and instrumentation manuals, which prompted us to change the name to the Astronomical Software and Documentation Service. ASDS was originally conceived to serve two purposes: to provide a useful Internet service in an area of expertise of the investigators (astronomical software), and as a research project to investigate various architectures for searching through a set of documents distributed across the Internet. Two of the co-investigators were then installing and maintaining astronomical software as their primary job responsibility. We felt that a service which incorporated our experience in this area would be more useful than a straightforward listing of software packages. The original concept was for a service based on the client/server model, which would function as a directory/referral service rather than as an archive. For performing the searches, we began our investigation with a decision to evaluate the Isite software from the Center for Networked Information Discovery and Retrieval (CNIDR). This software was intended as a replacement for Wide-Area Information Service (WAIS), a client/server technology for performing full-text searches through a set of documents. Isite had some additional features that we considered attractive, and we enjoyed the cooperation of the Isite developers, who were happy to have ASDS as a demonstration project. We ended up staying with the software throughout the project, making modifications to take advantage of new features as they came along, as well as influencing the software development. The Web interface to the search engine is provided by a gateway program written in C++ by a consultant to the project (A. Warnock).

Description: A great deal of progress has been made in recent years in decomposing the 2-D structure in the atmospheres of late-type stars. Doppler images of many photospheres single stars, T Tauri stars, Algols, RS CV(sub n) binaries to name a few - are regularly published (Strassmeier 1996; Richards and Albright 1996; Rice and Strassmeier 1996; Kuerster et al. 1994). Ultraviolet spectral images of chromospheres appear in the literature (e.g., Walter et al. 1987; Neff et al. 1989) but are less common owing to the difficult nature of obtaining complete phase coverage. Zeeman doppler images of magnetic fields are now feasible (e.g., Donati et al. 1992). Performing Doppler imaging of the same targets over many seasons has also been accomplished (e.g, Vogt et al. 1997). Even when a true image reconstruction is not possible due to poor spectral resolution, we can still infer a great deal about spatial structure if enough phases are observed. However, it is increasingly apparent that to make sense of recent results, many different spectral features spanning a range of formation temperature and density must be observed simultaneously for a coherent picture to emerge. Here we report on one such campaign. In 1996, we observed the southern hemisphere RS CV(sub n) binary V824 Ara (P=1(sup d).68, G5IV+K0V-IV-IV) over one complete stellar rotation with the Hubble Space Telescope and EUVE. In conjunction, radio and optical photometry and spectroscopy were obtained from the ground. Unique to this campaign is the complete phase coverage of a number of activity proxy indicators that cover source temperatures ranging from the photosphere to the corona.

Description: The present report concerns the following projects 'High energy emission from hot accretion disks from active galactic nuclei'; 'OSSE spectral timing and monitoring observations of Cygnus X- 1'; 'OSSE observations of blazars'; and 'Search for correlated time variations of bright EGRET blazars'. The most favored model for the central engine inAGNs is the supermassive black hole hypothesis (Rees 1978). The observed luminosities range from approx. 10 logical and 44-45 erg /s for objects such as Mk 421 and Seyferts to as much as approx. 10logical and 47 for powerful QSOs such as 3C 273 and 3C 279, a large fraction of the observed bolometric luminosity being, in all likelihood, beamed. As such, these objects are strong X-ray emitters (cf. Makino et al. 1987) and often undergo gamma-ray flaring detected at the EGRET range (Hartman et al. 1992) and in the case of one of two known nearby BL Lacs, Mk 421, at TeV energies as well (Punch et al. 1992, Macomb et al. 1995). Previous campaigns emphasizing radio through X-ray and even gamma-ray observations have generally found that the multiwavelength spectrum is adequately fit by a standard synchrotron self-Compton (SSC-cf. Jones et al. 1974) model of a relativistic jet (e.g. Makino et al. 1987 and Macomb et al. 1995 for the BL Lac object Mk 421) or inhomogeneous relativistic jet (Mufson et al 1990). It also was examined the gamma-gamma transperency constraints inblazars.

Description: This is the first report of a new contract. However, this project represents ongoing work, so there are completed tasks as well as newly started tasks to report. The project involves the completion of the IRAS Galaxy Atlas (IGA), a large image database produced using data from the Infrared Astronomical Satellite (IRAS). In this phase, the project switches from the production and characterization of the IGA to its use in astronomical research studies of massive star formation. The research utilizes the IGA as well as two other large data sets being produced by research partners.

Description: EUVE, ASCA, and XTE observed the eclipsing binary Algol (Beta Per) from 1-7 Feb. 96. The coordinated observation covered approximately 2 binary orbits of the system, with a net exposure of approximately 160 ksec for EUVE, 40 ksec for ASCA (in 4 pointing), and 90 ksec for XTE (in 45 pointings). We discuss results of modeling the combined EUVE, ASCA, and XTE data using continuous differential emission measure distributions, and provide constraints on the Fe abundance in the Algol system.

Description: We obtained ASCA spectra of the Seyfert 1 galaxy NGC 3516 in March 1995. Simultaneous far-UV observations were obtained with the Hopkins Ultraviolet Telescope on the Astro-2 shuttle mission. The ASCA spectrum shows a lightly absorbed power law of energy index 0.78. The low energy absorbing column is significantly less than previously seen. Prominent 0 VII and 0 VIII absorption edges are visible, but, consistent with the much lower total absorbing column, no Fe K absorption edge is detectable. A weak, narrow Fe K(alpha) emission line from cold material is present as well as a broad Fe K(alpha) line. These features are similar to those reported in other Seyfert 1 galaxies. A single warm absorber model provides only an imperfect description of the low energy absorption. In addition to a highly ionized absorber with ionization parameter U = 1.66 and a total column density of 1.4 x 10(exp 22)/sq cm, adding a lower ionization absorber with U = 0.32 and a total column of 6.9 x 10(exp 21)/sq cm significantly improves the fit. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to less than 160 km/s at 90% confidence. Turbulence at the sound speed of the photoionized gas provides the best fit. None of the warm absorber models fit to the X-ray spectrum can match the observed equivalent widths of all the UV absorption lines. Accounting for the X-ray and UV absorption simultaneously requires an absorbing region with a broad range of ionization parameters and column densities.

Description: This grant has supported my GHRS-related activities since 1990. This included both instrumental calibration activities and independent scientific research using the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The activities under this grant are essentially complete. Publications to date which have resulted in whole or in part from this grant are included.

Description: We have been obtained high-resolution data (20 in at 50 microns and 30 in at 100 microns) on the KAO using Paul Harvey's 2 x 10 element photometer in both scanning and nodding modes. The practical flux limit for scanning is about 100 Jy. For fainter sources, a nodding (beam-switching) mode, which spends more time on the source is used. This technique has been used successfully on objects as faint as 10 Jy; the 1 sigma noise for a 1 hour integration is about 1 Jy. Although not as sensitive as space-based instruments, the higher spatial resolution afforded by the KAO is essential in studying the far-infrared emission associated with young stars; in several cases we have been able to distinguish emission from multiple sources which were blended in the IRAS beam. In addition comparison of fluxes in the KAO beam to those in the much larger IRAS beam provides information on the extended low-level emission arising from the surrounding region.

Description: For many years the work at MIT aimed at the development of new concepts and technologies for space experiments in high-energy astrophysics, but not explicitly supported by flight programs, has been supported. This work has yielded new devices and techniques for X-ray astronomy, primarily low-noise, deep-depletion charge-coupled devices (CCDS) for spectrally-resolved X-ray imaging, and high-performance transmission gratings for high-resolution X-ray spectroscopy. Among the most significant recent achievements have been the development by G. Ricker and associates of the X-ray CCD camera flying on ASCA, and currently in development for AXAF and Astro-E, and the development by C. Canizares and associates of thick, 200 nm-period transmission gratings employing the phenomenon of phase shifting for high-resolution X-ray spectroscopy up to energies of 8- 1 0 keV that is essential for the operation of the AXAF High Energy Transmission Grating Spectrometer (HETGS). Through the current SR&T grant, the latter technology is now being extended successfully to the fabrication of 100 nm-period transmission gratings, which have twice the dispersion of the AXAF gratings. We note that, among other outcomes, the modest investments of past SR&T Grants at MIT resulted in the development of the key technologies for fully one-half of the scientific instrumentation on AXAF. In addition, NASA flight programs that have benefited from previous SR&T support at MIT include the SAS 3 X-ray Observatory, which carried the first rotation modulation collimator, the Focal Plane Crystal Spectrometer (FPCS) on the Einstein Observatory, the CCD cameras on ASCA and planned for Astro-E, the High Energy Transient Experiment (HETE), the Solar EUV Monitor on the Solar and Heliospheric Observatory (SOHO), the Medium Energy Neutral Atom imager (MENA) on the Image for Magnetopause-to-aurora Global Exploration (IMAGE) mission, and the recently-approved Two Wide-Angle Imaging Neutral-atom Spectrometers (TWINS) Mission of Opportunity.

Description: The project was designed to explore new morphological filtering, techniques for the removal of foreground Galactic 'Cirrus' emission from NASA Infrared Astronomical Satellite (IRAS) data, especially at 100 microns, using parallel processors as the main engine for achieving this result. The ultimate aim was to provide NASA with completely filtered data by the end of the grant period for the entire IRAS 100 and possibly 60 micron database. If successful, the filtered data would reveal many new sources of IR emission, especially at low galactic latitudes, which had previously been heavily confused with diffuse Galactic 'cirrus'.

Description: This report documents the observations of the HI filament LVC 88+36-2 with the Deep Survey/Spectrometers of EUVE. Detecting the shadow of this cloud in absorption might have proven the existence of a diffuse EUV background behind the cloud, and constrain the emission geometries of the hot plasma in the Local Interstellar Medium (LISM). By detecting diffuse emission in the EUVE spectrometers, it would also be possible to constrain the temperature and pressure of the emitting regions as well as determine whether or not the hot phase of the LISM is in equilibrium with cosmic elemental abundances. Unfortunately, we did not detect a cloud shadow with this set of observations. This is due to a combination of circumstances, but mostly due to the fact that EUV diffuse emission is weak compared to the background levels of EUVE. If a shadow exists in the EUVE, then it is less than 1% of the EUVE detector background of 1e-3 cts arcmin(sup -2) in the Deep Survey detector.

Description: Imaging of zeta greater than or equal to 3.4 radio galaxy fields below the Lyman continuum wavelength allows companion galaxies to be identified on the basis of red colors across the wavelength of redshifted Ly(alpha) and very red colors across the redshifted Lyman continuum. These arise due to a combination of absorption by intervening Ly(alpha) forest and Lyman-limit systems, and intrinsic Lyman-limit breaks in the galaxy spectral energy distribution caused by an Hi screen or breaks in stellar spectra. As a pilot study, we have imaged the field of the zeta = 3.8 radio galaxy 4C41.17 in U, V and R with the Auxiliary Port of the WHT. We find a number of potential companion galaxies, which require confirmation via spectroscopy or narrow-band imaging. The Lyman-limit in the spectrum of the radio galaxy itself and its implications for the origin of the UV flux is also discussed.

Description: We present a multiwavelength study of the interacting starburst galaxy NGC 7771, including new optical and ultra-violet spectra and a previously unpublished soft X-ray ROSAT image and spectrum. The far-infrared, radio, and X-ray fluxes suggest that a massive burst of star-formation is currently in progress but the small equivalent width of the Balmer emission lines (equivalent width H(alpha approximately equals 100 A), the weak UV flux, the low abundance of ionised oxygen, and the shape of the optical spectrum lead us to conclude that there are few 0 stars. This might normally suggest that star-formation has ceased but the galaxy's barred gravitational potential and large gas reserves imply that this should not be so, and we therefore consider other explanations. We argue that the observations cannot be due to effects of geometry, density bounded nebulae, or dust within the nebulae, and conclude that a truncated IMF is required. The dwarf galaxy NGC 7770 appears to be in the initial stages of a merger with NGC 7771, and the resulting tidal perturbations may have induced the apparent two-armed spiral pattern, and driven a substantial fraction of the disk gas inwards. The presence of a bulge in NGC 7771 may be moderating the starburst so that, while still occuring on a large scale with a supernova rate of 0.8-1/yr, it is less violent and the IMF has a relatively low upper mass limit. We find that there is a cluster of stars obscuring part of the starburst region, and we offer an explanation of its origin.

Description: Primarily composed of animation, movies, and stills, this video is divided into 12 segments or slugs as the video refers to them. They are: Global Map of Pluto, Images of Pluto, Surface Map of Pluto, Helix Nebula- NGC 7293, Gaseous Knots, Animation of the Formation of the Helix Nebula, Crab Nebula, Jupiter Aurora Movie, Birth of a Quasar, Merging Galaxies, and Spiral Galaxies.

Description: This video presents a chronological account of the Hubble Space Telescope. Using animation, movies, and stills it documents the design, development, launch, and repair mission to correct its optics. The second part of this video concentrates on the successes of Hubble. Included are the study of Galaxy Clusters, Black Holes, Jupiter animation, and Nebulas.

Description: Observations of Galactic, and extragalactic black hole candidates show that their spectra can be fitted by the thermal Comptonization spectra in the hard state and two components in the soft state. The first component is a black body shape spectrum and the second component is an extended power law with a spectral index of between 1 and 2. The spectral formation of Comptonized spectra in the presence of thermal and bulk motion is considered. In the soft state, when the disk luminosity is high, the emission region temperature is low. In the limit of low plasma temperature, the theoretical spectrum consists of two components: the soft input photons escaping without significant energy change, and a power law that extends to high energies. The spectral index is in the range between 1 and 2, depending on the mass accretion rate. The extended power law is the result of upscattering of soft disk photons in the bulk flow which takes place in the vicinity of the black hole. In the hard state, the disk luminosity is low, the electron temperature of the emission region is high and the thermal Comptonization is the dominant process in the formation of the resulting spectrum.

Description: The burst and transient source experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO) provides all sky monitoring capability, occultation analysis and occultation imaging which enables new and fainter sources to be searched for in relatively crowded fields. The occultation imaging technique is used in combination with an automated BATSE image scanner, allowing an analysis of large data sets of occultation images for detections of candidate sources and for the construction of source catalogs and data bases. This automated image scanner system is being tested on archival data in order to optimize the search and detection thresholds. The image search system, its calibration results and preliminary survey results on archival data are reported on. The aim of the survey is to identify a complete sample of black hole candidates in the galaxy and constrain the number of black hole systems and neutron star systems.

Description: Issues involved in galaxy unification through the two scenarios of unification through evolution and unification through orientation are reviewed, and the importance of observations at soft gamma ray energies for the characterization of the properties of blazars is discussed. The observation of blazars with the International Gamma Ray Astrophysics Laboratory (INTEGRAL) and the Compton Gamma Ray Observatory (CGRO) is considered. The spectral density field is described and the spectral energy distributions of different classes of galaxies are detailed. It is concluded that the scientific returns expected from INTEGRAL include: the strongest gamma ray tests for beaming gamma-gamma transparency arguments and the Elliot-Shapiro relationship; the discovery that infrared luminous galaxies harbor and fuel supermassive black holes; the discovery of variable spectral hardenings in quasars, and the identification of trends in the high energy behavior of radio galaxies, radio quasars and blazars.

Description: The infrared photometric and spectral observation of five gamma ray blazars in coordination with the energetic gamma ray experiment telescope (EGRET) onboard the Compton Gamma Ray Observatory is reported. The infrared measurements were made with a Cassegrain infrared camera and the mid-infrared large well imager at the Mt. Palomar 5 m telescope. The emphasis is on the three blazars observed simultaneously by EGRET and the ground-based telescope during viewing period 519. In addition to the acquisition of broadband spectral measurements for direct correlation with the 100 MeV EGRET observations, near infrared images were obtained, enabling a search for intra-day variability to be carried out.

Description: Ultraviolet spectra of four O stars in the Magellanic Clouds obtained with the faint object spectrograph of the Hubble Space Telescope are analyzed with respect to their metallicity. The metal abundances are derived from the stellar parameters and the mass loss rate with a two step procedure: hydrodynamic radiation-driven wind models with metallicity as a free parameter are constructed to fit the observed wind momentum rate and thus yield a dynamical metallicity, and synthetic spectra are computed for different metal abundances and compared to the observed spectra in order to obtain a spectroscopic metallicity.

Description: The Advanced X-ray Astrophysics Facility (AXAF) will carry a high resolution mirror, two imaging detectors, and two sets of transmission gratings. The Tycho catalog from the Hipparcos mission will serve as a primary part of the AXAF Guide and Aspect Star Catalog (AGASC). The incorporation of Tycho into AGASC will provide: accurate positions and magnitudes for target acquisition and guidance; the necessary colors for magnitude transformations to the AXAF aspect camera system; high internal astrometric accuracy for half-arcsecond, post-facto image reconstruction; and an external astrometric system.

Description: Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here first results from a multi-wavelength campaign undertaken from July to September 1996. This study includes X-ray data from the RXTE All Sky Monitor and BATSE, two-frequency data from the Nancay radio telescope, and infrared photometry from the 1.8 m Perkins telescope at Lowell Observatory. The first long-term well-sampled IR light curve of GRS 1915+105 is presented herein and is consistent with the interpretation of this source as a long-period binary. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities.

Description: In accordance with our proposal, we carried out and analyzed a successful Extreme Ultraviolet Explorer spectroscopic observation of the BL Lacertae object Mrk 421 in April/May 1995 (approx. 242 ksec useful time). During this period, the source underwent a flare that was detected also in simultaneous observations in the X-ray and TeV (gamma)ray energy bands. Our EUVE data, however, provided the best continuous coverage of the flare and therefore played a key role in the analysis of the multiwavelength observation campaign (Buckley et al. 1996). Our spectral analysis benefited from an efficient procedure that we employed for properly assessing the background contamination at the shortest wavelengths. As a result, we were able to identify strong absorption features at the shortest observed EUV wavelengths (approx. 65-75 A), which were missed in earlier, on axis EUVE observations that extended only down to approx. 75 A (Fruscione et al. 1996). Our observations and interpretation of Mrk 421 were described in Kartje et al. 1997 (see attached reprint). The results were also presented in a poster at the AGN session in the 18th Texas Symposium on Relativistic Astrophysicsheld (Chicago, December 1996). Our interpretation of the observations has formed the basis for a unified model of outflows in BL Lac objects and Broad Absorption Line QSOs (Kartje & Konigl 1997). Preliminary accounts of this work, which have included a description of the EUVE observations of BL Lac objects, were presented in posters in IAU Colloquium No. 163 on Accretion Phenomena and Associated Outflows (Port Douglas, July 1996) and in the Carnegie Observatories Workshop on Ejection of Matter from AGNs (Pasadena, February 1997).

Description: We have obtained the complete SED from 10 microns out to 1.3 mm for all of our sources. We have the FIR imaging data, processed to reveal the maximum angular resolution possible, which allows us to model the disk. To model the disk, we have high resolution millimeter interferometry data.

Description: Ames Research Center and UCSC have been working on the development of a Mid IR Camera for the KAO in order to search for extra galactic supernovae. The development of the camera and its associated data reduction software have been successfully completed. Spectral Imaging of the Orion Bar at 6.2 and 7.8 microns demonstrates the derotation and data reduction software which was developed.

Description: An expansion of the plate overlap method of astrometric data reduction to a single plate has been proposed and successfully tested. Each plate is (artificially) divided into sub-plates which can then be overlapped. This reduces the area of a 'plate' over which a plate model needs to accurately represent the relationship between measured coordinates and standard coordinates. Application is made to non-astrographic plates such as Schmidt plates and to wide-field astrographic plates. Indeed, the method is completely general and can be applied to any type of recording media.

Description: In our continuing investigation of highly evolved stars, we report new interferometric angular diameter observations of 5 carbon and 4 S-type Mira Variable stars, and 4 non-Mira S Stars. From the data effective temperatures and linear radii are calculated.

Description: This paper proposes a model-based training program for the skills necessary to operate advance avionics systems that incorporate advanced autopilots and fight management systems. The training model is based on a formalism, the operational procedure model, that represents the mission model, the rules, and the functions of a modem avionics system. This formalism has been defined such that it can be understood and shared by pilots, the avionics software, and design engineers. Each element of the software is defined in terms of its intent (What?), the rationale (Why?), and the resulting behavior (How?). The Advanced Computer Tutoring project at Carnegie Mellon University has developed a type of model-based, computer aided instructional technology called cognitive tutors. They summarize numerous studies showing that training times to a specified level of competence can be achieved in one third the time of conventional class room instruction. We are developing a similar model-based training program for the skills necessary to operation the avionics. The model underlying the instructional program and that simulates the effects of pilots entries and the behavior of the avionics is based on the operational procedure model. Pilots are given a series of vertical flightpath management problems. Entries that result in violations, such as failure to make a crossing restriction or violating the speed limits, result in error messages with instruction. At any time, the flightcrew can request suggestions on the appropriate set of actions. A similar and successful training program for basic skills for the FMS on the Boeing 737-300 was developed and evaluated. The results strongly support the claim that the training methodology can be adapted to the cockpit.

Description: BATSE has now accumulated over 1800 burst triggers. Catalog data are available at http://www.batse.msfc.nasa.gov/data/grb/catalog. Burst locations are posted usually within a day of data receipt. New calculations of the sky exposure are also now available. The most recent complete catalog (4B) includes data obtained using different energy intervals for triggering. A summary of the current data will be presented.

Description: Support for reduction and analysis of observations made with the Yorkes Observatory 60-channel far infrared camera on the Kuiper Airborne Observatory was funded through Federal Grant. Data was reduced and made available to the research group at Yorkes and guest observers, The reduced date is indexed on the World Wide Web. Portion of the data have been reported in the attached references.

Description: Herbig Ae/Be stars are intermediate mass pre-main sequence stars, the higher mass analogues to the T Tauri stars. Because of their higher mass, they are expected form more rapidly than the T Tauri stars. Whether the Herbig Ae/Be stars accrete only from collapsing infalling envelopes or whether accrete through geometrically flattened viscous accretion disks is of current debate. When the Herbig Ae/Be stars reach the main sequence they form a class called Vega-like stars which are known from their IR excesses to have debris disks, such as the famous beta Pictoris. The evolutionary scenario between the pre-main sequence Herbig Ae/Be stars and the main sequence Vega-like stars is not yet revealed and it bears on the possibility of the presence of Habitable Zone planets around the A stars. Photometric studies of Herbig Ae/Be stars have revealed that most are variable in the optical, and a subset of stars show non-periodic drops of about 2 magnitudes. These drops in visible light are accompanied by changes in their colors: at first the starlight becomes reddened, and then it becomes bluer, the polarization goes from less than 0.1 % to roughly 1% during these minima. The theory postulated by V. Grinnin is that large cometary bodies on highly eccentric orbits occult the star on their way to being sublimed, for systems that are viewed edge-on. This theory is one of several controversial theories about the nature of Herbig Ae/Be stars. A 5 year mid-IR spectrophotometric monitoring campaign was begun by Wooden and Butner in 1992 to look for correlations between the variations in visible photometry and mid-IR dust emission features. Generally the approximately 20 stars that have been observed by the NASA Ames HIFOGS spectrometer have been steady at 10 microns. There are a handful, however, that have shown variable mid-IR spectra, with 2 showing variations in both the continuum and features anti-correlated with visual photometry, and 3 showing variations in the emission features only while the continuum level remained unchanged. The first 2 stars mentioned probably have reprocessing envelopes. The other 3 stars gives important clues to the controversy over the geometry of the gas and dust around these pre-main sequence stars: the steady underlying 10 microns continuum and variable features indicates that an optically thick continuum probably arising from an accretion disk is decoupled from the optically thin emission features which may arise in a disk atmosphere. Bernadette Rodgers has joined this monitoring campaign in the near-IR using GRIMII with the goal of detecting variations in the hot dust continuum and the gas density in the dense accretion region close to these stars.

Description: The mid- and far-infrared (IR) spectra of the nebular phase of SM 987A spans 250 days through more than 1000 days after the event. Analysis of the spectra, largely obtained from the Kuiper Airborne Observatory, leads to a rich picture of the structure of the supernebula. The evidence for dust grain formation. In the nebula after about 580 days will be reviewed. The dust continuum emission spectrum was gray and dust appears to have condensed in optically thick 'clumps' throughout a significant fraction of the nebula. Additional information is contained in the original extended abstract.

Description: The SOFIA Science Working Group was established to help develop the plans and specifications for the next-generation airborne observatory ("SOFIA"), which is now under development. The P.I. has developed several astronomical instruments for the Kuiper Airborne Observatory, NASA's previous airborne astronomy platform (which was decommisioned in 1995 in preparation for SOFIA). SOFIA, which will be a 747 SP aircraft carrying a 2.7 meter diameter telescope, is a joint project sponsored by NASA and DLR (the German space agency), and is now under development by a consortium including Universities Space Research Association (USRA), Raytheon, Sterling Software, and United Airlines. Rather than develop the SOFIA observatory in-house, NASA decided to privatize the project by issuing a Request for Proposals (RFP). The respondents to this RFP were consortia of private organizations which together had the required facilities and expertise to be able to carry out the project; the winner was the group led by USRA. One of the main roles of the SSWG was to help develop the technical specifications for the SOFIA observatory. In particular, the SSWG provided advice to NASA on the specifications that were written into the RFP, particularly those which had an important impact on the scientific productivity of the observatory. These specifications were discussed at the meetings of the SSWG, which were held primarily at NASA/Ames (in California) and at NASA Headquarters (in Washington DC). Apart from these meetings, members of the SSWG were expected to perform more detailed analyses of the impact of certain parameters and specifications on the performance of astronomical instruments. The SSWG ended its activities with the selection of the USRA team in January 1997.

Description: We describe a search of archival data from the Burst and Transient Source Experiment (BATSE). The purpose of the search is to find astronomically interesting transients that did not activate the burst-detection (or "trigger") system on board the spacecraft. Our search is sensitive to events with peak fluxes (on the 1.024 s timescale) that are lower by a factor of approximately 2 than can be detected with the on-board burst trigger. In a search of 345 days of archival data, we detected 91 events in the 50-300 keV range that resemble classical gamma-ray bursts but that did not activate the on-board burst trigger. We also detected 110 low-energy (25-50 keV) events of unknown origin that may include activity from' soft gamma repeater (SGR) 1806-20 and bursts and flares from X-ray binaries. This paper gives the occurrence times, estimated source directions, durations, peak fluxes, and fluences for the 91 gamma-ray burst candidates. The direction and intensity distributions of these bursts imply that the biases inherent in the on-board trigger mechanism have not significantly affected the completeness of the published BATSE gamma-ray burst catalogs.

Description: This report summarizes work made possible by NASA's Kuiper Airborne Observatory. The results of the work have appeared in over 80 papers. The publications fall in three main areas: instrumentation, observations, and analysis. Although there is considerable overlap between these categories it will be convenient to group them separately.

Description: The cluster of galaxies MS0440+02, originally discovered through its X-ray emission, was part of an optical observational program to search for arcs and arclets in a complete sample of X-ray luminous, medium-distant clusters of galaxies. Mauna Kea CCD images of MS0440+02 showed a remarkable optical morphology. The core of the cluster contains 6 bright galaxies and numerous fainter ones embedded in a low surface brightness halo. Besides, MS0440+02 is the most spectacular example that we have found of an arc system in a compact condensed cluster, with arcs symmetrically distributed to draw almost perfect circles around the cluster center. Giant arcs are magnified images of distant galaxies, gravitationally distorted by massive foreground clusters. It is of great importance to compare the results of the lensing studies with those derived from X-ray observations, as the two are independent methods of studying the mass distribution. Thus MS0440+02 was the ideal target to obtain temperature measurement with ASCA and good spatial resolution X-ray observations with ROSAT. The X-ray data have been used in conjunction with Hubble Space Telescope observations to put more stringent constrains on the mass estimates. Most of the different wavelength datasets have been reduced and analyzed. Mass determinations have been separately obtained from galaxy virial motions and X-ray profile fitting using the cluster gas temperature as measured by the ASCA satellite. Assuming that the hot gas is in hydrostatic equilibrium and in a spherical potential, we find from the X-ray data a mass distribution profile that is well described by a Beta model. From the multiple images formed by gravitational lensing (HST data) using the modelling of the gravitational lensed arcs, we have derived Beta model. To reconcile the mass estimates we have explored the possibility of having a supercluster surrounding the MOS0440 cluster, that is a model with two isothermal spheres, one embedded inside the other. These results have been published or are in press.

Description: Initial stages of a study whose aim was to assemble and reduce the Voyager spacecraft observations of cataclysmic variables made with the UV spectrometers, and to collate and present the Voyager spectra along with IUE spectra of the same targets, are discussed.

Description: Progress in determining the gravitational energy conversion balance in accreting white dwarf stars is reported. Detailed photospheric spectra of the white dwarf stars in the brightest magnetic cataclysmic binaries, in the region where most of the energy is radiated by the stellar atmosphere - in the extreme ultraviolet band is obtained.

Description: In early 1993, funding for the NUVIEWS experiment was initiated. The experiment was completed and delivered to Wallops Flight Facility in March 1996, where it has completed flight integration and testing successfully. We feel that the three year development time was too long by a year, and that the history deserves some explanation. The construction of four complete four-mirror telescope systems with unique multilayer coatings, superpolished aspheres, and four large-format, high-resolution microchannel-plate detectors required a substantial effort. Our original design included only three telescopes, but we added a fourth 18 months ago to ensure rejection of all potential contaminating line features. A six-month SMEX Definition study in 1994 required substantial efforts by key personnel. There was great synergy here: the four NUVIEWS detectors are prototypes for the SMEX UV-survey mission (JUNO). In 1993, the Principal Investigator C. Martin took a position at Caltech. The transition of the laboratory from Columbia to Caltech was unfortunately timed and led to more delays, including an additional laboratory move and calibration tank/clean room reconstruction. Following the May NUVIEWS launch, the laboratory move to Caltech will be complete.

Description: This grant was awarded to Dr. C. Megan Urry of the Space Telescope Science Institute in response to two successful ADP proposals to use archival Ginga and Rosat X-ray data for 'Testing the Pairs-Reflection model with X-Ray Spectral Variability' (in collaboration with Paola Grandi, now at the University of Rome) and 'X-Ray Properties of Complete Samples of Radio-Selected BL Lacertae Objects' (in collaboration with then-graduate student Rita Sambruna, now a post-doc at Goddard Space Flight Center). In addition, post-docs Joseph Pesce and Elena Pian, and graduate student Matthew O'Dowd, have worked on several aspects of these projects. The grant was originally awarded on 3/01/94; this report covers the full period, through May 1997. We have completed our project on the X-ray properties of radio-selected BL Lacs.

Description: The highly structured nature of the outer solar atmosphere seems to be intimately linked to the presence, at the solar surface, of magnetic fields that have been generated inside the Sun and have emerged to the surface. The corona is brightest (and also hottest) at just those locations where the magnetic field has emerged from inside the Sun. Dynamo theory predicts that strong magnetic fields will be generated deep in the solar interior and that bundles or 'ropes' of magnetic flux will float to the surface. When this happens, a magnetically bipolar region will become visible, extending above the surface in a three-dimensional structure. The field lines penetrate through the surface, showing two magnetic poles, and also exhibit a three-dimensional structure above the surface. The structure created by the field emergence is rooted in the (relatively) cool photosphere and extends through the chromosphere and transition region to the corona. Thus, the magnetic field creates a region, called an active region, which contains portions at temperatures from less than 10(exp 4) K to greater than 10(exp 6) K, and is therefore visible at wavelengths from the infrared through x-rays. The locations where the magnetic field leaves and reenters the visible surface are called the 'footpoints' of the coronal structures associated with the magnetic field. The magnetic fields themselves are not directly visible. However, the hot coronal plasma is, for the most part, constrained to follow the direction of the magnetic field lines in the atmosphere. Now, 100 years after the discovery of x-rays by Wilhelm Roentgen in 1896, we can routinely make observations of the solar corona from outside the Earth's atmosphere in this region of the electromagnetic spectrum. As shown by comparing x-ray images with magnetograms, the bright corona over these bipolar magnetic regions consists of closed structures that seem to follow the orientation of the magnetic field. Although we can see down to the photosphere at x-ray wavelengths when observing the disk of the Sun, this part of the solar atmosphere emits so little that far from the peak of its Planck curve it appears dark in x-ray images. This impression of hot plasma following the magnetic field direction is further strengthened by quantitative studies that calculate coronal magnetic field strength and direction based on photospheric measurements and compare them with the observed brightness and location of the x-ray emitting structures. Such comparisons make it clear that, for the most part, the hot plasma conforms to the geometry of the magnetic field and that the coronal brightness is strongly linked to the strength of the magnetic fields which have erupted to the solar surface from the interior. It is also the case that the larger-scale, fainter corona, as well as coronal holes, are strongly influenced by the large-scale solar magnetic field. We may get a small hint of the reason that the coronal plasma outlines the direction of B by examining the thermal conductivity of a hot plasma in the presence of a magnetic field. This quantity has enormously different values in the directions parallel and perpendicular to the field for a coronal temperature of 10(exp 6) K, a particle density of 10(exp 9)/cu cm and a magnetic field strength of 100 G, the conductivity along the field is approximately 13 orders of magnitude greater than that perpendicular to the field. It is therefore not surprising that a parcel of plasma which is locally heated would conduct that heat preferentially in the direction of the field. We also note that the thermal conductivity parallel to the magnetic field increases with temperature T, while the perpendicular conductivity decreases. To the extent that the loop aspect ratio, i.e., the ratio of loop length to loop width, is determined by the thermal conductivity, we would expect that higher temperature loops are longer and thinner than cooler ones. However, if the loop width becomes smaller than the spatial resolution of the observing instrument, this effect will not be directly observable. For organizational purposes, we provide a listing of some scientific objectives for a Solar-B x-ray telescope, arranged in terms of identifiable features in the corona.

Description: This report concerns one of the major observational studies in the ISO Central Programme, the ISO Normal Galaxy Survey. This is a survey of an unbiased sample of spiral and lenticular galaxies selected from the Revised Shapley-Ames Catalog. It is therefore optically-selected, with a brightness limit of blue magnitude = 12, and otherwise randomly chosen. The original sample included 150 galaxies, but this was reduced to 74 when the allocated observing time was expended because the ISO overheads encountered in flight were much larger than predicted.

Description: This research grant supported an active sounding rocket program at Penn State University over a period of over 10 years. During this period, the grant supported at least 8 graduate students in Astronomy & Astrophysics for at least a portion of their research. During the same period, our group was involved in seven sounding rocket flights, launched from White Sands, New Mexico, and from Woomera, Australia. Most of these rocket flights, and most of the work supported by this grant, involved the use of X-ray CCD cameras. The first X-ray CCD camera ever flown in space was our sounding rocket observation of SN1987A (flight 36.030 in 1987). Subsequent flights utilized improved CCD detectors, culminating in the'state-of-the-art EEV detector developed for our CUBIC mission, which was flown on 36.093 last May. Data from the last three flights, which observed the diffuse X-ray background with CCDS, include detection of the OVII He(alpha) line in the high latitude diffuse background and detection of the Mg XI He(alpha) line in the North Polar Spur. These results have been reported at meetings of the American Astronomical Society and the SPIE. The analysis of flights 36.092 and 36.106 is part of Jeff Mendenhall's PhD thesis and will be published in the Astrophysical Journal next year. The 36.093 data are currently being analyzed by PhD student Laura Cawley. From 1990 to 1996 this grant supported our development and launch of the CUBIC instrument on the SAC-B satellite, which was designed to measure the spectrum of the soft X-ray diffuse background with moderate energy resolution and high S/N ratio. Unfortunately, this mission terminated shortly after launch due to a failure of the Pegasus XL launch vehicle. This work resulted in publication of 4 papers in the SPIE Proceedings and four others in refereed journals, in addition to several other conference proceedings and contributed papers. In addition to the CCD flights described above, this grant has supported preliminary development of a new sounding rocket payload utilizing a replicated Ni mirror that is being developed at PSU in collaboration with MSFC. Initial testing of the coating technology has produced promising results.

Description: We report on the discovery and hard X-ray (20-70 keV) observations of the 4.45 second period transient X-ray pulsar GRO J1750-27 with the BATSE all-sky monitor on board CCRO. A relatively faint outburst (〈 30 mCrab peak) lasting at least 60 days was observed during which the spin-up rate peaked at 38 pHz/sec and was correlated with the pulsed intensity. An orbit with a period of 29.8 days was found. The large spin-up rate, spin period and orbital period together suggest that accretion is occurring from a disk and that the outburst is a 'giant' outburst typical of a Be/X-ray transient system. No optical counterpart has been reported yet.

Description: Inspection of pulse shapes obtained by the Burst and Transient Source Experiment (BATSE) Pulsar Monitor for the high mass X-ray binary pulsar OAO 1657-415 shows that significant variations have occurred. For example, power in the second harmonic of the pulse increased by 50 percent during TJD 10358 - 10374, at the beginning of a slow transition from spinup to spindown.This source is shown to exhibit alternating intervals of spinup and spindown of similar magnitudes. A study will be presented of pulse shape, intensity and spectral variability of the source, with a search for any correlation with spin behavior.

Description: The accreting pulsar GX 301-2 (P = 680 s) has been observed continuously by the large-area detectors of the Burst and Transient Source Experiment (BATSE) instrument on the Compton Gamma Ray Observatory since 1991 April 5. Orbital parameters determined from these data are consistent with previous measurements, with improved accuracy in the current orbital epoch. The most striking features in the pulsar frequency history are two steady and rapid spin-up episodes, with a dot-nu approximately equal to (3_5) x 10(exp -12) Hz/s, each lasting for about 30 days. They probably represent the formation of transient accretion disks in this wind-fed pulsar. Except for these spin-up episodes, there are virtually no net changes in the neutron star spin frequency on long timescales. We suggest that the long-term spin-up trend observed since 1984 (dot-nu is approximately equals 2x10(exp -13) Hz/s) may be due entirely to brief (approximately 20 days) spin-up episodes similar to those we have discovered. We assess different accretion models and their ability to explain the orbital phase dependence of the observed flux. In addition to the previously observed preperiastron peak at orbital phase 0.956 +/- 0.022, we also find a smaller peak close to - at orbital phase 0.498 +/- 0.057. We show that if the companion star's effective temperature is less than 22,000 K, then it must have a mass M(sub c) 〈 70 solar mass and a radius R(sub c) 〈 85 solar radius so as not to overfill the tidal lobe at periastron. In order not to overflow the Roche lobe at periastron, the corresponding values are M(sub c) 〈 55 solar mass and R(sub c) 〈 68 solar radius. These constraints are nearly at odds with the reclassification of the companion as a B1 Ia + hypergiant.

Description: Recent numerical and analytic studies of planetary orbits have demonstrated the importance of resonances and chaos in destabilizing planetary systems. Newton's "clockwork" description of regular, predictable planetary orbits has been replaced by a view in which many systems can have long but finite lifetimes. This new knowledge has altered our perceptions of the later stages of planetary growth and of the stability of planetary systems. Stability criteria are inexact and time dependent. Most previous studies have focused on the effects in initial planetary orbits on the stability of the system. We are conducting an investigation which focuses on the dependence of stability criteria on planetary mass. Synthetic systems are created by increasing the masses of the planets in our Solar System or of the moons of a particular planet; these systems are then integrated until orbit crossing occurs. We have found that over some ranges, the time until orbit crossing varies to a good approximation as a power clothe factor by which the masses of the secondaries arc increased; some scatter occurs as a consequence of vie chaotic nature of orbital evolution. The slope of this power law varies substantially from system to system, and for moons it is mildly dependent on the inclusion of the planet's quadrupole moment in the gravitational potential.