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The Space Telescope Imaging Spectrograph (STIS) and the Cosmic Origins Spectrograph (COS) are the two optical-UV spectrographs on board the Hubble Space Telescope. To determine the wavelength scale for individual science observations, internal arc lamp spectra accompany most observations of external targets. Here we present a detailed analysis of the changes in the COS and STIS internal lamp fluxes and spectra over time, and also compare our results to pre-launch ground testing, and to laboratory accelerated aging testing of similar lamps. Most of the analysis presented here focuses on the behaviour of the lamps in the far-UV (FUV). We find that the STIS LINE lamp has faded by a factor of ~15 in the very short FUV wavelengths (1150-1200A) over the 13-year period on which STIS was in space, a much steeper fading than predicted from accelerated aging tests in the laboratory. We also find that all STIS lamps have faded during the period in which the spectrograph was not operational (2004-2009) thus pointing to on-orbit conditions as an additional and important cause of lamp fading. We report that the COS P1 lamp output appears to decline with usage with a similar slope as the LINE and HITM1 lamps on STIS. Finally, we recommend switching from the LINE to the HITM2 lamp for a more efficient wavelength calibration of the STIS settings covering the very short FUV wavelengths.

Bias and Dark reference files are part of the basic reduction of the CCD data taken by the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). At STScI, the STIS team has been creating these reference files using the Bias and Dark Pipeline. This pipeline system starts with automatic retrieval of bias and dark exposures from the HST archive after they have been ingested. After data retrieval, a number of automatic scripts is executed in a manner compatible with the OPUS pipeline architecture. We encourage any group looking to streamline a stepwise calibration process to look into this software.

In August 2004, the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) ceased operation, due to a failure in the Side 2 Low Voltage Power Supply (LVPS2). LVPS2 provided power to the entire instrument, including all detectors and mechanisms. Following the LVPS2 failure, a team was assembled to analyze the fault and to determine if STIS repair (STIS-R) was feasible. The team concluded that by replacing a power supply board within LVPS2, STIS could be brought back to full functionality. STIS-R will be conducted during Servicing Mission 4 (SM4), and will consist of replacing the power supply board and a new passive cooling system. STIS-R will restore full function of the instrument with one of the two redundant sides of the instrument. In this presentation, we focus on the technical aspects associated with STISR.

The Space Telescope European Coordinating Facility's (ST-ECF) lamp project, funded directly by the European Space Agency (ESA), is dedicated to the study of hollow cathode calibration lamps as they are used onboard the Hubble Space Telescope (HST). There are two main objectives: First, we have measured the spectra of Pt/Cr-Ne lamps in order to obtain accurate and reliable wavelengths for all emission lines between 115 and 320 nm. This wavelength range corresponds to the coverage provided by the Space Telescope Imaging Spectrograph (STIS) Echelle modes. Extensive laboratory measurements were performed at the National Institute of Standard and Technology (NIST) using their 10.7 m normal incidence spectrograph and a Fourier Transform Spectrograph. Until now no good laboratory wavelengths for Cr had been available and their addition has a major impact on the wavelength calibration, in particular in the near UV. The new line list is being used in conjunction with the physical instrument model of STIS which is employed to derive an improved wavelength calibration as part of the STIS Calibration Enhancement (STIS-CE) effort. Second, we attempt to gain a better understanding of the performance of such lamps and the physical processes involved in their long term operations. Among the issues studied are the change of the spectrum as a function of current, its change as a function of time and the tolerances of alignment. The bulk of the measurements were performed on flight spares from STIS and on new space qualified lamps for the accelerated aging test. The original flight lamps from the Faint Object Spectrograph (FOS) and the Goddard High Resolution Spectrograph (GHRS) are the only lamps ever to be measured after their return from space. Together with the spectra archived from six years of on-orbit operations they provide a unique data set for studying ageing effects in these lamps. The new Pt/Cr-Ne line list has been successfully applied in the STIS-CE effort. Thereby the ST-ECF's lamp project directly leads to an improvement in the quality of scientific observations of existing HST spectrographs. Our findings also constitute important lessons for the design and operations of future UV and optical spectrographs in space.

The Wide Field Camera 3 (WFC3) is an instrument which is being developed for the Hubble Space Telescope. It will have a UV/VIS channel which will include two 2051 X 4096 pixel, thin, backside illuminated CCDs. These CCDs produce interference fringes in narrow band or monochromatic light images taken in the 700 nm to 1000 nm wavelength range. We have obtained 146 monochromatic images for each of the four flight candidate CCDs. These images can be used to model the physical structure of the CCD, which are described by a set of parameters deduced by solving the Fresnel equations for the absorption within the CCD as a function of wavelength. We have used the formalism developed to model the Space Telescope Imaging Spectrograph's CCD by Malumuth et. al. to determine the free parameters for a large portion of one of the WFC3 flight candidate CCDs. From these fits we are able to evaluate the ability to fit the fringing of real data by comparing a model fringe flat to an observed fringe flat. We find that we should be able to reduce the observed fringe amplitude by a factor of five or better. Finally we show that for a certain class of object (extended emission line object with a variety of radial velocities) this model is an excellent method for removing the effect of fringing.

The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for late February 2002. The instrument has three cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, is a high throughput (43% at 700 nm, including the HST OTA), wide field (200' X 204'), optical and I-band optimized camera. The second, the High Resolution Channel (HRC) has a 26' X 29' field of view, it is optimized for the near-UV (a peak throughput of 24% at 500 nm) and is critically sampled at approximately 630 nm. The third camera, the Solar-Blind Camera is a far-UV, photon counting array that has a relatively high throughput over a 26' X 29' field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048 X 4096 pixel CCDs and the HRC a 1024 X 1024 CCD based on the Space Telescope Imaging Spectrograph 21 micrometers pixel CCD. In this paper we review the performance of the flight detectors selected for ACS.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The CCD detector in the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope is a backside-illuminated, 1024 x 1024 pixel device developed by Scientific Imaging Technologies for the STIS program. It supports a wide-ranging observing program of imaging and spectroscopy over the 200-1000 nm wavelength range at the high angular resolution of HST. In the three years since launch, radiation damage to the CCD (primarily due to high energy protons encountered in crossings of the South Atlantic Anomaly) has caused a degradation in the charge transfer efficiency (CTE) and an increase in the dark current. The growth in hot pixel count has been readily observable over the entire period since launch; the CTE degradation has become apparent more slowly, as it has evolved with time and as in-flight calibration test methods have improved. We report here on the calibration tests developed to measure the CTE performance in flight, on the results of those tests, on the monitoring of the CCD dark current, and on potential amelioration strategies for minimizing the scientific impact of the decline in STIS CCD performance.

The Space Telescope Imaging Spectrograph (STIS) is a versatile HST instrument covering the 115 - 1000 nm wavelength range in a variety of spectroscopic and imaging modes. Coverage of the ultraviolet range (115 - 310 nm) is provided by two Multi- Anode Microchannel Array (MAMA) detectors built by Ball Aerospace. The FUV MAMA covers the 115 - 170 nm range using an opaque CsI photocathode on the microchannel plate; the NUV MAMA covers the 165 - 310 nm range using a semi-transparent Cs2Te photocathode on the detector window. Both MAMAS utilize a 1024 X 1024 anode format, but detected photon events are positioned to half the spacing of the anode lines, leading to a 2048 X 2048 format for the final readout. The active area of each detector is 25.6 X 25.6 mm. Since the installation of STIS onto the Hubble Space Telescope (HST) in February 1997, the MAMAs have carried out a varied program of astronomical observing and in-flight calibration. The detectors have performed extremely well. In this report, we briefly describe the design of the STIS MAMA detectors, provide illustrative examples of their scientific use on HST, and summarize their technical performance in orbit, in such areas as sensitivity, resolution, flat-field uniformity and stability, signal-to-noise capability, dynamic range, and background.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for June 2001. The instrument has three different cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, will be a high throughput, wide field optical and I-band optimized camera that is half-critically sampled at approximately 570 nm. The second, the High Resolution Channel (HRC) has a 26 inch by 29 inch field of view, it is optimized for the near- UV and is critically sampled at approximately 630 nm. The third camera, the Solar-Blind Camera is a far-UV, photon counting array that has a relatively high throughput over a 26 inch by 29 inch field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048 by 4096 pixel CCDs and the HRC a 1024 by 1024 CCD based on the Space Telescope Imaging Spectrograph 21 micrometers pixel CCD. IN this paper we review the performances of the devices baselined as flight candidates.

The Space Telescope Imaging Spectrograph (STIS) operates from the UV to near IR providing a general purpose, imaging spectroscopic capability. An internal, two mirror relay system corrects the spherical aberration and astigmatism present at the STIS field position. Low and medium resolution imaging spectroscopy is possible throughout the spectral range and over the 25 arcsecond UV and 52 arcsecond visible fields. High resolution echelle spectroscopy capability is also provided in the UV. Target acquisition is accomplished using the STIS cameras, either UV or visible; these cameras may also be used to provide broad band imaging over the complete spectral range or with the small selection of available bandpass filters. A wide selection of slits and apertures permit various combinations of spectral resolution and field size in all modes. On board calibration lamps provide wavelength calibration and flat fielding capability. We report here on the optical performance of STIS as determined during orbital verification.

The advanced camera for surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the third servicing mission scheduled for 1999. ACS, along with the previously installed space telescope imaging spectrograph and near IR camera/multi-object spectrograph, consume significantly more power than the first generation of instruments. Additionally, the larger apertures of these instruments make parallel operations scientifically exciting. These parallel operations demand that all of the instruments operate in their highest power states simultaneously for extended periods of time. These and other factors have resulted in much higher temperatures inside the aft shroud where the ACS will be installed. As a result, new approaches are required to transfer heat inside the instrument and reject it away from the telescope. This paper describes the unique thermal systems required by the ACS. These include capillary pump loops and flexible and rigid heat pipes.

The Space Telescope Imaging Spectrograph (STIS), installed into the Hubble Space Telescope (HST) during the second servicing mission (SSM) in February 1197, has undergone the required servicing mission orbital verification (SMOV). The overall sensitivity of STIS is summarized for direct imagery in the visible with the charge coupled device (CCD), the near UV multi-anode microchannel-array (NUV MAMA) and the far UV MAMA (FUV MAMA) detectors and likewise for the spectroscopic modes. The FUV MAMA has exceedingly low background. The NUV MAMA has a higher, temperature-dependent background due to window phosphorescence. The principle gains of the CCD over WFPCs for limiting imaging sensitivity are: high quantum efficiency, wide bandpass, low dark current and low readout-noise. The CCD, like the WFPC2 CCDs, must ge annealed periodically to heat the hot pixels generated by radiation hits. Throughput of all modes has been stable at the 1 percent level or better except for the far UV, where sensitivity is dropping slowly across the order, but more rapidly below the Lyman alpha, and beyond 150 nm. This loss in sensitivity may be due to contamination similar to that which affected the first generation HST instruments. The thermal environment for STIS is warmer than specified in the HST Interface Control Document with the result that the back end of the STIS optical bench is not under positive thermal control. Temperature swings occur due to the spacecraft solar orientation and also due to power cycling of the MAMA low voltage power supplies that are turned off during orbits that encounter the South Atlantic Anomaly. Some motion of spectral and direct image formats occurs on the detector that is correlatable with changing aft bulkhead temperature and changes in external heatloads. The MAMA detectors are capable of time-tagging photon events within 125 microsecond resolution. The Crab Pulsar was used as a time standard and demonstrates the desired performance.

The Space Telescope Imaging Spectrograph (STIS), which was successfully installed into the Hubble Space Telescope (HST) in February 1997, has the capability to perform a powerful set of autonomous target acquisition functions. The STIS target acquisition capabilities have been tested during the initial commissioning of the instrument and are currently being used to acquire astronomical targets to support the HST Guest Observer program and the ongoing instrument calibration activities. STIS can perform several types of autonomous target acquisition sequences, all of which make use of the STIS instrument's imaging capabilities and are controlled by flight software executing out of the STIS control section microprocessor, an Intel 80386. The types of acquisitions include the location of point sources, the location of the brightest area in a diffuse or extended target, the location of point sources in crowded fields, and the centering of targets within any of the STIS spectroscopic slits. In order to move located targets into slits and center them there, the STIS control section flight software makes requests for HST pointing corrections, via special engineering telemetry sent to the HST main flight computer. The accuracy of the target acquisition tested in orbit has exceeded pre-flight specifications.

The Space Telescope Imaging Spectrograph (STIS) is a second- generation instrument for the Hubble Space Telescope (HST), designed to cover the 115-1000 nm wavelength range in a versatile array of spectroscopic and imaging modes that take advantage of the angular resolution, unobstructed wavelength coverage, and dark sky offered by the HST. STIS was successfully installed into HST in 1997 February and has since completed a year of orbital checkout, capabilities that it brings to HST, illustrate those capabilities with examples drawn from the first year of STIS observing, and describe at a top level the on-orbit performance of the STIS hardware. We also point the reader to related papers that describe particular aspects of the STIS design, performance, or scientific usage in more detail.

Two multi-anode microchannel array (MAMA) detectors were fabricated at Ball Aerospace Technology Corporation for the Space Telescope Imaging Spectrograph (STIS) which was installed into the Hubble Space Telescope in February 1997. The photometric stability of the opaque CsI and semi- transparent Cs2Te sealed MAMA tubes has been characterized as a function of operating voltage and illumination conditions. A total exposure of 5 by 107 counts per pixel results in < 1 percent change in the detection quantum efficiency (DQE), which is attributed to conditioning of the microchannel plate (MCP) during tube processing. Employing good engineering practices to power supply design mitigates the effects of these components in long term detector stability. Other factors contributing to the photometric stability include the use of a curved channel MCP, photocathode processing, hydrocarbon free ultra high vacuum processing and sealed tube processing techniques. Contributions to the low resolution mode DQE stability are discussed along with empirical results on high resolution mode stability.

The space telescope imaging spectrograph (STIS) was designed as a versatile spectrograph capable of maintaining or exceeding the spectroscopic capabilities of both the Goddard High Resolution Spectrograph and the Faint Object Spectrograph (FOS) over the broad bandpass extending from the UV through the visible. STIS achieves performance gains over the aforementioned first generation Hubble Space Telescope instruments primarily through the use of large a real detectors in both the UV and visible regions of the spectrum. Simultaneous spatial and spectral coverage is provided through long slit or slitless spectroscopy. This paper will review the detector design and in-flight performance. Attention will be focussed on the key issue of S/N performance. Spectra obtained during the first few months of operation, illustrate that high signal-to-noise spectra can be obtained while exploiting STIS's multiplexing advantage. From analysis of a single spectrum of GD153, with counting statistics of approximately 165, a S/N of approximately 130 is achieved per spectral resolution element in the FUV. In the NUV a single spectrum of GRW + 70D5824, with counting statistics of approximately 200, yields a S/N of approximately 150 per spectral resolution element. An even higher S/N capability is illustrated through the use of the fixed pattern split slits in the medium resolution echelle modes where observations of BD28D42 yield a signal-to-noise of approximately 250 and approximately 350 per spectral resolution element in the FUV and NUV respectively.

This paper provides a high level summary of STIS, the space telescope imaging spectrograph, and describes the principle hurdles overcome during the servicing mission orbital verification in order to bring STIS to operational status as HST's optical and UV spectrograph. Also described are the approach taken to develop STIS for effective GO use and the approach taken to the on-orbit calibration of this complex and capable instrument. Lastly, we provide a description of the current operational and calibration status of STIS, including many recent results. STIS is performing extremely well as a science instrument. Monitoring projections suggest it should continue to operate effectively throughout its projected 13 year mission, barring unforeseen effects or complications.

During the ground calibration of the Space Telescope Imaging Spectrograph (STIS) large scattered light haloes were identified in images of point sources and long slit spectral images at long wavelengths (greater than 750 nm). The long wavelength scattering was traced to the SITe 1024 X 1024 CCD and its header package, raising concerns for the performance of the Advanced Camera for Surveys (ACS) CCD detectors. ACS is a third generation axial instrument for the Hubble Space Telescope (HST) and will be installed during the 1999 Servicing Mission. Two of the ACS imaging channels employ SITe CCDs, so the ACS team have conducted a study of the long- wavelength scattering, in collaboration with SITe, to assess the impact to the ACS science program and develop a solution. In this paper we discuss our solution, its implementation on ACS CCDs, and describe the results of initial tests.

The STIS instrument was installed into HST in February 1997 during the Servicing Mission 2. It has almost completed checkout and is beginning its science program, and is working well. Several scientific demonstration observations were taken to illustrate some of the range of scientific uses and modes of observation of STIS.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The second servicing mission for the Hubble Space Telescope (HST), scheduled for early 1997, will be the first change in the spectroscopic capabilities of HST since its initial deployment. The Space Telescope Imaging Spectrograph (STIS) is a multipurpose instrument covering the far ultraviolet (FUV) through near infrared spectral range. It acquires spectra at several spectral resolutions, which facilitates observations at many distances and brightnesses. STIS will replace both of the first generation spectrographs, the Goddard High Resolution Spectrograph and the Faint Object Spectrograph. This will allow the addition of a Near- Infrared Camera. STIS required the development and testing of many high quality diffraction gratings, including several very difficult echelles for the FUV. The methods and results of this grating development program are presented. The results serve as a snapshot of industry capabilities for producing high quality spaceborne diffraction gratings.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Space Telescope Imaging Spectrograph (STIS) uses two 1K by 1K photon counting array (PCA) detector systems. Design of the PCA detector systems is described in this paper. These detector systems are similar in many ways and are mechanical mirror images of each other but cover different UV wavelength bands. A top-down design methodology was used to produce the two detector systems that feature: manufacturability, serviceability to the component level, system-level replacement without optical realignment or calibration, and a high level of parts commonality for cost control. The design meets the Space Telescope's structural, thermal, and electromagnetic compatibility requirements as well as electro-static discharge compatibility requirements of MIL-STD-1686A.

The Space Telescope Imaging Spectrograph (STIS), a next-generation instrument for the Hubble Space Telescope, has begun the fabrication of the flight units (plus spares) of the multi-anode microchannel array (MAMA) detectors. STIS will fly two MAMA detectors, one with a CsI photocathode covering the short-wavelength (1150-1750 angstrom) band and a second with Cs2Te covering the 1650-3100 angstrom band. Good tube yields continue to be realized with many of the MAMAs exceeding flight specifications by substantial amounts in key parameters. Evnironmental testing on the earlier engineering model units (EMUs) demonstrate the ruggedness of the tube design. We present performance results of the STIS flight MAMAs which have been fabricated to date. Life and other engineering tests on EMU detectors will be presented as well.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The near infrared camera and multi-object spectrometer (NICMOS) and the space telescope imaging spectrograph (STIS) are next-generation orbital replacement instruments for the Hubble Space Telescope (HST). Ball Aerospace Systems Group is currently designing and building these instruments for the National Aeronautics and Space Administration. Substantial components of the flight software for these two instruments are being designed in common in order to save development costs and to make in-orbit commanding and maintenance of the flight software easier. The majority of the flight software (FSW) for both NICMOS and STIS is embedded within the electronics of the instruments. This paper begins with an overview of the HST-environment in which the embedded FSW for both STIS and NICMOS executes. The paper then describes: (1) the common electronics environment in which the FSW executes, (2) the FSW development environment, (3) the FSW real-time environment, (4) the method for in-orbit commanding of instrument operations via macros, (5) the method for gathering analog hardware engineering data, (6) the method for commanding the STIS CCD detectors and the NICMOS detectors, (7) the structure and management of the science data buffer, (8) fault management, (9) the collection of diagnostic data, (10) the capabilities for uplinking new FSW code and data once the instruments are in orbit, and (11) instrument-specific software executing in the NASA Standard Spacecraft Computer (NSSC-1), external to STIS and NICMOS.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Space Telescope Imaging Spectrograph is a second generation ultraviolet and visible light spectrograph being developed by NASA for installation on the Hubble Space Telescope during the planned 1997 servicing mission. The current schedule calls for the instrument to be completed in the spring of 1996, with an extensive period of functional, environmental, and calibration tests during the summer. A calibration plan has been developed to ensure that the basic performance characteristics of this versatile instrument will be verified and documented before launch, and that the necessary operational and data reduction databases will be adequatley populated. Our strategies to measure the radiometric sensitivity, flat-field response, dispersion relations, resolving power, scattered light, slit functions, and other properties are described. As the execution of the calibration program is still over a year away (at the time of the conference at which this paper was presented), discussion and suggestions from the engineering and scientific communities will be welcomed.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The space telescope imaging spectrograph (STIS) is currently being developed for in-orbit installation onto the Hubble Space Telescope in 1997, where it will cover the wavelength range from 115 to 1000 nm in a variety of spectroscopic and imaging modes. For coverage of the 305 - 1000 nm region (and backup of the 165 - 305 nm) region, STIS will employ a custom CCD detector which has been developed at Scientific Imaging Technologies (SITe; formerly Tektronix CCD Products Group). This backside-illuminated device incorporates a proprietary SITe backside treatment and anti-reflective coating to extend the useful quantum efficiency shortward of 200 nm. It also features low noise amplifiers, multi-pinned-phase implants, mini-channel implants, and four quadrant readout. The CCD is thermo-electrically cooled to an operating temperature of -80 degree(s)C within a sealed, evacuated housing with its exterior at room temperature to minimize the condensation of absorbing contaminants in orbit. It is coupled to a set of low noise, flexible, fault-tolerant electronics. Both housing and electronics are being developed by the STIS prime contractor, Ball Aerospace & Communications Group. We describe here the design features, performance, and fabrication status of the STIS CCD and its associated subsystem, along with results of radiation testing.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The space telescope imaging spectrograph (STIS), a next-generation instrument for the Hubble Space Telescope, has fabricated several engineering model units (EMUs) of the multi-anode microchannel array (MAMA) detectors. Good tube yields have been realized in producing these EMUs and some have performances suitable for flight. One of these EMU MAMAs has been operated for substantial periods of time after having undergone both shake and thermal environmental testing. A second will undergo similar environmental tests later this year. An earlier demonstration tube has been used extensively for over a year to evaluate STIS gratings in the Goddard Diffraction Grating Evaluation Facility. The STIS MAMA detectors have now matured to the point where half of the total test and evaluation effort is concerned with the characterization of subtle processes, a level of characterization needed to achieve data with a signal-to-noise ratio in excess of 100. We present test results from these EMUs including detailed analysis of data collected with vacuum chambers specifically designed for the evaluation of these detectors.

Potential transmitting materials for the STIS mission are being considered for order sorters, in-flight calibration filters, detector windows and calibration lamps. In this paper we examine the changes in spectral transmission characteristics with radiation dosage during a mission lifetime. A radiation environment for a 593 km altitude, 28 degree inclination orbit, for solar minimum and solar maximum, assuming a spherical shielding of 2 gms/cm 2 has been assumed. The dosage for protons is 0.392 Krad (Al)/Yr. and 0.217 Krad (Al)/Yr. for solar minimum and solar maximum respectively. To simulate the mission radiation environment Harvard Cyclotron Laboratory (HCL) has been used. Spectral transmission was measured between 210 nm and 3200 nm using a Perkin Elmer Lambda 9 monochromator. Below 210 nm a one meter McPherson vacuum monochromator was used. Transmission curves for all samples were obtained before irradiation and compared for equality in transmission.

We have constructed a high resolution imaging spectrograph for use as a payload in a sounding rocket experiment. The spectrograph employs a modified Ebert-Fastie design using a LiF predispersing prism and a replica of the E1 echelle grating developed for the Space Telescope Imaging Spectrograph. The spectrograph is used as a focal plane instrument of the Jupiter Telescope, a Cassegrain telescope constructed exclusively for use as a sounding rocket payload. The telescope and spectrograph were launched from the White Sands Missile Range on May 4, 1991 to observe the H Ly-alpha line profile spatially resolved across the disk of Jupiter in the north-south and east-west directions, and to measure the H Ly-alpha emission line profile from interplanetary hydrogen associated with the local interstellar medium.

Development of a 2048-squared CCD for a second-generation Space Telescope instrument has produced some very encouraging devices. The first experimental lot of 10 devices have very few defects, dark currents of less than 40 electrons/pixel/hour at -80 C, readout noise levels of less than 4 electrons rms and excellent charge transfer efficiency at signal levels of less than 10 electrons.

The design of the diffraction grating evaluation facility (DGEF) for the evaluation of the performance of new-technology diffraction gratings, being presently established at the Goddard Space Flight Center, is discussed. The DGEF was devised to evaluate gratings of the proposed spectrographic designs for future missions, such as Lyman or the Far UV Spectroscopic Explorer, and second-generation Space Telescope instruments such as the Space Telescope Imaging Spectrograph (STIS). Test results for several STIS new technology gratings, including an ion-etched cross dispenser, are presented. Diagrams of the DGEF and of an optical layout are included.

Multianode microchannel array (MAMA) detector systems with formats of 256 x 1024 pixels and active areas of 6 x 26 mm are now under evaluation at visible, UV and soft X-ray wavelengths. Very-large-format versions of the MAMA detectors with formats of 2048 x 2048 pixels and active areas of 52 x 52 mm are under development for use in the NASA Goddard Space Telescope Imaging Spectrograph (STIS). Open-structure versions of these detectors with Cs I photocathodes can provide a high-resolution imaging capability at EUV and soft X-ray wavelengths and can deliver a maximum count rate from each array in excess of 10 to the 6th counts/s. In addition, these detector systems have the unique capability to determine the arrival time of a detected photon to an accuracy of 100 ns or better. The construction, mode of operation, and performance characteristics of the MAMA detectors are described, and the program for the development of the very-large-format detectors is outlined.

The preliminary design for the Space Telescope Imaging Spectrograph (STIS), which has been selected by NASA for definition study for future flight as a second-generation instrument on the Hubble Space Telescope (HST), is presented. STIS is a two-dimensional spectrograph that will operate from 1050 A to 11,000 A at the limiting HST resolution of 0.05 arcsec FWHM, with spectral resolutions of 100, 1200, 20,000, and 100,000 and a maximum field-of-view of 50 x 50 arcsec. Its basic operating modes include echelle model, long slit mode, slitless spectrograph mode, coronographic spectroscopy, photon time-tagging, and direct imaging. Research objectives are active galactic nuclei, the intergalactic medium, global properties of galaxies, the origin of stellar systems, stelalr spectral variability, and spectrographic mapping of solar system processes.