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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.

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 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 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.