FLIGHT DYNAMICS' STAR CATALOG DATABASE SKY2000 MASTER CATALOG / SKYMAP SOFTWARE CAPABILITIES The SKYMAP Star Catalog System consists of a Master Catalog stellar database and a collection of utility software designed to create and maintain the database and to generate derivative mission star catalogs (run catalogs). THE MASTER CATALOG The original SKYMAP Master Catalog was generated in the early 1970's. Incremental updates and corrections were made over the following years but the first complete revision of the source data occurred with Version 4.0. This revision also served to meet the requirements of the new CCD-based star trackers and to produce a unique, consolidated source of astrometric information which can be used by the astronomical community. In addition, many derived quantities were removed and wideband and photometric data in the R (red) and I (infrared) systems were added. Additional upgrades and improvements were made in Version 4.0a as well. The version following Version 4.0a is the most recent version and has been named the SKY2000 Master Catalog due to the change in format as well as other extensive modifications. This version is discussed in detail in the following paragraph. The SKY2000 Master Catalog The new SKY2000 Master Catalog - Version 1 contains 299,485 records with 463 bytes of data (plus 1 byte control character) per entry and has data based in the J2000 coordinate system. This version contains the following upgrades: Rehosting of the catalog from a PC-based system to an HP workstation using UNIX Modification of the catalog format to conform to well-known source catalogs Addition of new star identification information Generation of more realistic positional errors Correction and expansion of double- and multiple-star data Incorporation of improved reference magnitudes for stars not having photoelectrically measured values A conference paper on the SKY2000 Master Catalog was written that describes these upgrades in detail. There are some deficiencies that exist in the SKY2000 Master Catalog that we are aware of. These items will be researched and corrected in future SKY2000 Master Catalog releases. Please send comments, questions, or corrections to David Tracewell. -------------------------------------------------------------------------------- SKY2000 Conference Paper Latest report on SKY2000 - Version 1 (back to Home ) -------------------------------------------------------------------------------- The SKY2000 Version 1 Master Catalog Format Description Star catalog numbers(SKYMAP,HD,DM,HR,WDS,and PPM) and Flamsteed names Star positions, proper motions, and parallax Magnitudes and color indices Spectral types Multiple star information Variable star information Red Magnitude Data Formatted Data Detailed Format description The SKY2000 Version 2 Master Catalog Format Description Star catalog numbers(SKYMAP,HD,DM,HR,WDS,and PPM) and Flamsteed names Star positions, proper motions, and parallax Magnitudes and color indices Spectral types Multiple star information Variable star information Red Magnitude Data Formatted Data Detailed Format description -------------------------------------------------------------------------------- SKY2000 Master Catalog Deficiencies A list of SKY2000 - Version 1 deficiencies (back to Home ) -------------------------------------------------------------------------------- The SKY2000 Version 1 Master Catalog is available for download in 2 different formats: A version compressed using GZIP (24.5 Mb). Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. A self-extracting version compressed using WIN Zip (~23.5 Mb): Windows 95/NT users (32 bit) Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. The SKYMAP SKY2000 Version 2 Master Catalog Version 2 of the SKY2000 Master Catalog was completed in September of 1998 and represents a substantial improvement over Version 1. A high proportion of the astrometric data in Version 2 comes from ESA's Hipparcos mission, by way of the Hipparcos Output, Hipparcos Component, and Tycho Catalogues. Astrometric data are also present from USNO's ACT Catalog and the European Tycho Reference Catalogue, both of which refine the proper motions in the original Tycho catalog by an order of magnitude. While some objects still retain ACRS and PPM data, the proportion is very small and there are no stars left in the catalog which do not have astrometric quality positions. A large number of photoelectric data on the Johnson system (V, B) has been added from the Tycho Catalogue, such that there are now very few stars in SKY2000 that lack photoelectric data. More than 4000 stars observed by the Ball CT-601 star trackers on the RXTE spacecraft now have observed CCD ST magnitudes in Version 2. IAU designations based on J2000.0 positions have been added to the catalog, while all previous identifiers (SKY2000, HD, SAO, DM, HR, WDS, PPM, AG, bright- and variable-star designations) have been retained. The IAU-approved identifiers allow new objects to be inserted without disrupting the natural order of the principal catalog identifier. The SKY2000 Master Catalog, Version 2 is available for download in 2 different formats: A version compressed using GZIP (~32 Mb). Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. A self-extracting version compressed using WIN Zip (~32 Mb): Windows 95/NT users (32 bit) Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. SKY2000 Master Catalog Version 2 Deficiencies A list of SKY2000 Version 2 deficiencies. (back to Home ) MISSION STAR CATALOGS The primary function of any Master Catalog is the generation of star catalogs to support attitude determination and analysis for satellites equipped with star sensors. Star catalogs are a subset of the Master Catalog and have a standard, eight-word Multi-Modular Spacecraft (MMS) mission star catalog format. * EUVE Star Catalog - unavailable presently: SKYMAP 3.7 * UARS Star Catalog - unavailable presently: SKYMAP 3.7 * SOHO Star Catalog * XTE Star Catalog * SWAS Star Catalog * LANDSAT-7 Star Catalog * EOS AM-1 Star Catalog * (back to Home page) --------------------------------------------------------------------------- RUN CATALOG Format Description A RUN star catalog has eight (8) columns with the following characteristics: 1. SKYMAP Number 2. G.C.I. unit vector (x) mean J2000 3. G.C.I. unit vector (y) mean J2000 4. G.C.I. unit vector (Z) mean J2000 5. Instrumental magnitude for CCD 6. Proper motion 7. Quality Flags (4 bit flags) 8. Color Word (back to Home ) --------------------------------------------------------------------------- EUVE Star Catalog (back to catalog selection) (back to Home page) --------------------------------------------------------------------------- UARS Star Catalog (back to catalog selection) (back to Home ) --------------------------------------------------------------------------- SOHO Star Catalog Solar and Heliospheric Observatory (SOHO) SOHO, one of the International Solar-Terrestrial Physics (ISTP) missions, is designed to gather information on coronal dynamics, solar flux, and solar oscillations. SOHO is a joint mission between the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). Data gathered from SOHO will be used with data obtained from other ISTP missions to understand processes in the Sun-Earth interaction chain. SOHO was launched from an expendable launch vehicle. SOHO will be placed into a halo orbit about the sunward libration point (L1) with a planned mission life of 2 years with enough fuel for a 4-year extension. The SOHO spacecraft will maintain a Sun-pointing attitude throughout the course of the mission using a fine-pointing Sun sensor and will maintain the roll orientation about the Sun-pointing axis by using a gyro during maneuvers and a charge-coupled device (CCD) star tracker otherwise. The star tracker is nominally mounted with its boresight 90 degrees to the spacecraft X-axis, which is nominally parallel to the Sun-pointing line. Early in the mission, the X-axis will be aligned with the Sun line. The SOHO star tracker is produced by Officine Galileo and incorporates a band-pass filter to provide tracker spectral response characteristics similar to the visual spectrum. SOHO SKYMAP Mission Run Catalog * The Run Catalog generated has stars as faint as +8.0 instrumental magnitudes. * The star tracker's instrument magnitude is normalized to the visual magnitude of spectral class A0V stars. * The quality of a potential guide star in the SOHO Run Catalog is gauged by the magnitude of the various quality flags within the limits given below: o Variability: largest known variability in amplitude flagged is 10 magnitudes; o Color: the largest difference between the V magnitude and the Instrumental magnitude flagged is 2 magnitudes; o Multiplicity: This flag maps a multiple star related to this star in the range of 0.5 and 6 magnitudes difference. o Net position error of primary stars as a result of near neighbor interference between -1 and 1000 arcseconds; o Position measurement errors contained in the SKYMAP Master Catalog between 0 and 150 (arcseconds); o Instrumental magnitude errors written to the SWAS Run Catalog between 0 and 3.25; o Near-neighbor trackability flag was not turned on; o Near-neighbor identifiability flag was not turned on. * The SKYMAP Version 4.0 Master Catalog was used to generate the SOHO Run Catalog. The SOHO mission star catalog has eight (8) columns with the following characteristics: 1. SKYMAP Number 2. G.C.I. unit vector (x) mean J2000 3. G.C.I. unit vector (y) mean J2000 4. G.C.I. unit vector (Z) mean J2000 5. Instrumental magnitude 6. Proper motion 7. Quality Flags (4 bit flags) 8. Color Word Link to SOHO Star Catalog (5.9 Mbytes) * Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. (back to catalog selection) (back to home page) --------------------------------------------------------------------------- XTE Star Catalog The X-ray Timing Explorer (XTE) The X-ray Timing Explorer (XTE) is designed to gather data about X-ray-emitting objects within the Milky Way and beyond. XTE performs timing studies of X-ray sources, which vary in the intensity of their emissions, and spectral studies, which will reveal emission processes and locations of regions emitting X-rays. The spacecraft was launched on a Delta II rocket on December 30, 1995 from Cape Canaveral Air Station in Florida. The XTE mission baseline requires a 580 km low earth orbit with a 23 degree inclination. XTE is a three-axis stabilized inertial pointing spacecraft. The attitude determination and control hardware of the spacecraft consists of one onboard computer (OBC), two three-axis magnetometers (TAM), eight coarse Sun sensors (CSSs), two digital Sun sensor (DSS), three two-axis inertial reference units (IRUs), two charged-couple device (CCD) star trackers, two three-axis magnetic torquer assemblies (MTA), one four-wheel reaction wheel assembly (RWA) and one experimental inertial fiber-optic gyro (IFOG). XTE SKYMAP Mission Run Catalog 1. The Run Catalog generated has stars as faint as +7.0 instrumental magnitudes. 2. The star tracker instrumental magnitude is normalized to the visual magnitude of spectral class A0V stars. 3. To prevent anomalous star intensity and position due to the images of near neighbors, during the Run Catalog generation, the near neighbors of each star catalog star are considered. 4. The quality of a potential guide star in the XTE Run Catalog is gauged by the magnitude of the various quality flags within the limits given below: (a) variability: the largest variability mapped in amplitude is 10 magnitudes; (b) color: the value of the largest mapped difference between the V magnitude and the I magnitude is 3 magnitudes; (c) multiplicity: a star is considered to be a multiple star if the magnitude difference between the star and its nearest star is between 0.5 and 6 magnitudes; if the nearest star is either greater than or equal to 6 magnitudes fainter or the nearest star is less than 2.0 arcseconds away (which is the sensor resolution ), it is not likely that it is a multiple star; if the above conditions are not present the star is not a multiple star or multiple star is treated as a near neighbor; (d) Net position error of primary stars as a result of near neighbor interference between 10 and 1000 arcseconds is mapped; (e) All position measurement errors contained in the XTE Run Catalog are mapped; (f) Instrumental magnitude uncertainties written to the XTE Run Catalog between 0 and 2.5 are mapped; (g) Near-neighbor trackability maps the nearest star either brighter than or up to 4 magnitudes fainter for angles to the star between 0 and 1.0 degrees; (h) Near-neighbor identifiability maps the nearest star within 1 magnitude for angles to the star between 0 and 5.0 degrees. 5. The SKYMAP Version 4.0a Master Catalog is used to generate the XTE Run Catalog. Observed instrumental magnitudes from XTE tracked stars were analyzed and compared to the SKYMAP magnitude predictions, and based on this analysis, a correlation was found between the size of the difference in the magnitudes and the star's spectral class. All the instrumental magnitudes in the XTE Run Catalog were then tweaked based on the correlation found. The XTE mission star catalog has eight columns with the following characteristics: 1. SKYMAP Number 2. G.C.I. unit vector (x) mean J2000 3. G.C.I. unit vector (y) mean J2000 4. G.C.I. unit vector (z) mean J2000 5. Instrumental magnitude for CCD 6. Proper Motion 7. Quality Flags (4 bit flags) 8. Color Word Link to the XTE Star Catalog ( 3.5 Mbytes) * Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. (back to catalog selection) (back to home page) --------------------------------------------------------------------------- SWAS Star Catalog Submillimeter Wave Astronomy Satellite (SWAS) The Submillimeter Wave Astronomy Satellite (SWAS) is designed to investigate molecular clouds in the galactic plane and to study extragalactic sources of radiation in the submillimeter range. The main science instrument on the spacecraft consists of an off-axis Cassegrain telescope, a two-channel receiver, an acoustic optical spectrometer, instrument control electronics and a thermal control system. The mission has a planned lifetime of 36 months. The SWAS mission baseline requires a 600 km circular orbit with a 65 degree inclination. SWAS is a three-axis stabilized inertial pointing spacecraft. The attitude determination and control hardware of the spacecraft consists of one onboard computer (OBC), one three-axis magnetometer (TAM), six coarse Sun sensors (CSSs), one digital Sun sensor (DSS), three two-axis inertial reference units (IRUs), one charged-couple device (CCD) star tracker, one three-axis magnetic torquer assembly (MTA) and one four-wheel reaction wheel assembly (RWA). Science data will be collected when the spacecraft is pointing at specific source and off-source targets as specified from the ground. Three different scenarios for science data collection are planned. In one scenario the spacecraft will remain at one attitude for an extended period of time. In a second scenario, the spacecraft will nod between on-source and off-source targets every minute, for up to 20 minutes at a time. In the third scenario, the spacecraft will map a region of the galactic plane by pointing at a series of preset gridpoints 2 arcminutes apart. Science data will be collected during these three scenarios. SWAS SKYMAP Mission Run Catalog 1. The Run Catalog generated has stars as faint as +7.5 instrumental magnitudes. 2. The star tracker instrumental magnitude is normalized to the visual magnitude of spectral class G0V stars. 3. To prevent anomalous star intensity and position due to the images of near neighbors, during the Run Catalog generation, the near neighbors of each star catalog star are considered. 4. The quality of a potential guide star in the SWAS Run Catalog is gauged by the magnitude of the various quality flags within the limits given below: (a) variability: the largest variability mapped in amplitude is 10 magnitudes; (b) color: the value of the largest mapped difference between the V magnitude and the I magnitude is 3 magnitudes; (c) multiplicity: a star is considered to be a multiple star if the magnitude difference between the star and its nearest star is between 0.5 and 6 magnitudes; if the nearest star is either greater than or equal to 6 magnitudes fainter or the nearest star is less than 2.0 arcseconds away (which is the sensor resolution ) it is not likely that it is a multiple star; if the above conditions are not present the star is not a multiple star or multiple star is treated as a near neighbor; (d) Net position error of primary stars as a result of near neighbor interference between -1 and 1000 arcseconds is mapped; (e) Position measurement errors contained in the SWAS Run Catalog between 0 and 150 (arcseconds) are mapped; (f) Instrumental magnitude uncertainties written to the SWAS Run Catalog between 0 and 2.5 are mapped; (g) Near-neighbor trackability maps the nearest star either brighter than or up to 4 magnitudes fainter for angles to the star between 0 and 1.0 degrees; (h) Near-neighbor identifiability maps the nearest star within 1 magnitude for angles to the star between 0 and 5.0 degrees. 5. The SKYMAP Version 4.0a Master Catalog is used to generate the SWAS Run Catalog. The SWAS mission star catalog has eight (8) columns with the following characteristics: 1. SKYMAP Number 2. G.C.I. unit vector (x) mean J2000 3. G.C.I. unit vector (y) mean J2000 4. G.C.I. unit vector (Z) mean J2000 5. Instrumental magnitude for CCD 6. Proper motion 7. Quality Flags (4 bit flags) 8. Color Word Link to SWAS Star Catalog (3.6 Mbytes) * Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. (back to catalog selection) (back to home page) --------------------------------------------------------------------------- LANDSAT-7 SKYMAP Mission Run Catalog Landsat-7 Satellite Landsat-7 is designed to provide remote sensing of the Earth and return data that can either be processed into images or used in digital form for scientific, military and commercial applications. Its multispectral imaging payload consists of the Enhanced Thematic Mapper Plus (ETM+), which is kept continuously pointing towards the Earth during each orbit by the attitude control subsystem (ACS) employed by the satellite. It will provide data continuity with the Landsat-4 and -5 payloads, as well as add a panchromatic band and an enhanced resolution of the long wavelength infrared band. The major sensors and actuators on Landsat-7 that provide control of its orbit and attitude consist of 1 inertial measurement unit (IMU), 1 celestial sensor assembly (CSA), 1 Earth sensor assembly (ESA), 2 three-axis magnetometers (TAMs), 1 coarse Sun sensor (CSS) which includes 2 array-mounted and 1 body-mounted CSS units, 4 reaction wheel assemblies (RWAs), 2 magnetic torquer rods (MTRs), hydrazine jets (orbit adjust and momentum management), 1 rotatable solar array (SA), 3 gimbaled X-band antennas (GXAs) and 2 S-band Omni antennas. Landsat-7 spacecraft will be launched on a Delta II Expendable Launch Vehicle (ELV) from the west coast of the United States in May 1998. It will be injected into a Sun-synchronous near-polar orbit (98.2 degree inclination) at a nominal altitude of 705 kilometers with a descending node mean local time (MLT) of 10:00 A.M. Its life time is expected to be 5 years. For Landsat-7, both a Run Catalog and a Supplemental Catalog were generated. The Run Catalog provides data based on mission-specific requirements. For example, the Run Catalog contains instrumental magnitudes that are calculated using the Landsat-7 sensor sensitivity curve with the observed visual or red magnitudes of the star. The Supplemental Catalog is generated after the Run Catalog and contains the same set of stars that are in the Run Catalog. However, this catalog provides additional generic star information that is not contained in the Run Catalog, and that the mission needs for analysis purposes. The formats for these catalogs are described below. Landsat-7 SKYMAP Mission Run Catalog 1. The Run Catalog generated has stars as faint as +4.75 instrumental magnitudes. 2. The star tracker instrumental magnitude is normalized to the visual magnitude of spectral class A0V stars. 3. To prevent anomalous star intensity and position due to the images of near neighbors, during the Run Catalog generation, the near neighbors of each star catalog star are considered. 4. The quality of a potential guide star in the Landsat-7 Run Catalog is gauged by the magnitude of the various quality flags within the limits given below: (a) variability: the largest variability amplitude bin flag is set to 10 magnitudes; (b) color: the value of the largest bin giving the difference between the V magnitude and the I magnitude is 3 magnitudes; (c) multiplicity: This flag is set so that the star is flagged as a multiple star if the magnitude difference between the star and its nearest star is between 0.5 and 6 magnitudes; if the nearest star is either greater than or equal to 6 magnitudes fainter or the nearest star is less than 4.2 arcseconds away (which is the sensor resolution ) it is not likely that it is a multiple star; if the above conditions are not present the star is not a multiple star or multiple star is treated as a near neighbor; (d) Net position error of primary stars as a result of near neighbor interference between -1 and 1000 arcseconds is mapped; (e) Position measurement errors contained in the Landsat-7 Run Catalog are flagged for errors with values between 0 and 150 (arcseconds); (f) Instrumental magnitude uncertainties written to the Landsat-7 Run Catalog between 0 and 2.5; (g) Near-neighbor trackability maps the nearest star either brighter than or up to 4 magnitudes fainter for angles to the star between 0 and 1.0 degrees; (h) Near-neighbor identifiability maps the nearest star within 1 magnitude for angles to the star between 0 and 5.0 degrees. 5. The SKYMAP Version 4.0a Master Catalog is used to generate the Landsat-7 Run Catalog. Landsat-7 Supplemental Catalog A description of the Landsat-7 Supplemental Catalog format is given below: Field 1 (1-8) SKYMAP number of the star. Field 2 (10-19) right ascension of the star, in hours, minutes and seconds of time. Field 3 (21-30) declination of the star, in degrees, minutes and seconds of arc. Field 4 (32-37) position uncertainty for the star, in arcseconds. Field 5 (39-47) proper motion of the star in right ascension, in arcseconds/year. Field 6 (49-57) proper motion of the star in declination, in arcseconds/year. Field 7 (59-65) radial velocity of the star, in kilometers/second. Field 8 (67-72) trigonometric parallax of the star, in arcseconds. Field 9 (74-79) parallax uncertainty of the star, in arcseconds. Link to LANDSAT-7 Star Catalog (326 Kbytes) * Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. Link to LANDSAT-7 Star Supplemental Catalog (241 Kbytes) * Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. (back to catalog selection) (back to home page) --------------------------------------------------------------------------- EOS AM-1 Star Catalog Mission to Planet Earth (MTPE) is the NASA contribution to the USGCRP (United States Global Change Research Program) and the Earth Observing System (EOS) is the centerpiece of that effort. EOS is a fifteen-year program consisting of a series of Earth remote sensing spacecraft to study the atmosphere, oceans, cyrosphere, biosphere and solid Earth. Key issues to be explored and understood are the interrelationships between these components of the Earth system and the flow of energy, water and chemicals among them. Each series will have several spacecraft, thereby enabling continuous observations over the program's lifetime. When fully implemented the EOS constellation will have as many as five spacecraft (one from each series) in orbit simultaneously and conducting routine operations. The first series of spacecraft to launch is the AM series ( AM refers to the morning equatorial crossing of 10:30 GMT required to accommodate cloud-cover constraints), with the first launch designated as EOS-AM1. The EOS AM-1 spacecraft will be launched by an Atlas II AS expendable launch vehicle from the Western Test Range (WTR) at Vandenberg Air Force Base (VAFB) into a frozen, Sun-synchronous orbit inclined at 98.2 degrees. The mean altitude will be 705 km over the Equator, with a descending node mean local time (MLT) of 10:30 AM (+/- 15 minutes). Currently, launch is scheduled for June 1998, with a required 5-year lifetime. EOS AM-1 will fly in a constellation with Landsat-7. The spacecraft will carry instruments capable of producing high-resolution images of land, water, and clouds from the visible through infrared spectrum. The EOS AM spacecraft will provide detailed measurements of clouds, aerosols and the Earth's radiative energy balance, together with measurements of the land surface and its interaction with the atmosphere through exchanges of energy, carbon and water. These interactive processes present scientific questions of the highest priority to understanding global climate change. The instruments will provide a 5-year data set on the atmospheric radiative balance and the physical and radiative properties of clouds (ASTER, CERES, MISR, MODIS); high resolution observations of land, ocean, ice surface and cloud processes (ASTER, MISR, MODIS); vertical profiles of important greenhouse gases (MOPITT, MODIS); vegetation structure and dynamics (MISR, MODIS, ASTER); and volcanology (ASTER, MISR, MODIS). Specific information on the EOS AM1 science instrument complement may be obtained from: http://newsroom.gsfc.nasa.gov/fos/eos-am1/eos-am1.html and from http://eospso.gsfc.nasa.gov/ EOS AM-1 is a 3-axis stabilized, Earth-pointing spacecraft. The Attitude Determination and Control System (ADACS) consists of an Onboard Computer (OBC) and the following sensors and actuators: * Earth Sensor Assembly (ESA) (2) * Three-Axis Magnetometer (TAM) (2) * Coarse Sun Sensor (CSS) (2) * Digital Fine Sun Sensor (DSS) (1) * CCD Solid State Star Tracker (SSST) (2) * Inertial Reference Unit (IRU) (2 units of 3-axis gyros) * Magnetic Torquer Assembly (MTA) (1 unit of 3-axes) * Reaction Wheel Assembly (RWA) (1 unit, 4 wheels) * Attitude Control Thrusters (6 Primary, 6 Redundant) EOS AM1 Mission Star Catalog A star catalog was produced using SKYMAP Version 4.0a to support the EOS AM1 onboard and ground based attitude control/determination systems. The Multimission Modular Spacecraft run catalog format is used as shown below: 1. The Run Catalog generated has stars as faint as +5.7 instrumental magnitudes. 2. The star tracker instrumental magnitude is normalized to the visual magnitude of spectral class G2V stars. 3. To prevent anomalous star intensity and position due to the images of near neighbors, during the Run Catalog generation, the near neighbors of each star catalog star are considered. 4. The quality of a potential guide star in the XTE Run Catalog is gauged by the magnitude of the various quality flags within the limits given below: (a) variability: the largest variability mapped in amplitude is 10 magnitudes; (b) color: the range of differences between the V magnitude and the I magnitude is -10 to + 3 magnitudes; (c) multiplicity: a star is considered to be a multiple star if the magnitude difference between the star and its nearest star is between 0.25 and 5 magnitudes; if the nearest star is either greater than or equal to 5 magnitudes fainter or the nearest star is less than 5.0 arcseconds away (which is the sensor resolution ), it is not likely that it is a multiple star; if the above conditions are not present the star is not a multiple star or multiple star is treated as a near neighbor; (d) Net position error of primary stars as a result of near neighbor interference between 0 and 1000 arcseconds is mapped; (e) All position measurement errors contained in the EOS AM1 Run Catalog are mapped; (f) Instrumental magnitude uncertainties written to the EOS AM1 Run Catalog between 0 and 2.5 are mapped with those between 2.5 and 999.0 contained in a single bin; (g) Near-neighbor trackability maps the nearest star either brighter than or up to 5 magnitudes fainter for angles to the star between 0 and 1.0 degrees; (h) Near-neighbor identifiability maps the nearest star within 0.75 magnitude for angles to the star between between 0 and 5.0 degrees. 5. The SKYMAP Version 4.0a Master Catalog is used to generate the EOS AM1 Run Catalog. The EOS AM1 mission star catalog has eight columns with the following characteristics: 1. SKYMAP Number 2. G.C.I. unit vector (x) mean J2000 3. G.C.I. unit vector (y) mean J2000 4. G.C.I. unit vector (z) mean J2000 5. Instrumental magnitude for CCD 6. Proper Motion 7. Quality Flags (4 bit flags) 8. Color Word Significant post processing was done on the Run Catalog by FDD and McDonnel-Douglas personnel to reduce the catalog to ~700 of the best guide stars with equal distribution. The final report by P. Kudva (in Microsoft Word format) is available here. Link to the EOS AM1 Star Catalog (~ 75 Kbytes) * Netscape Users: Place the cursor here, hold down the right mouse button, and select Save this Link as... to FTP the file to your local disk. (back to catalog selection) (back to home page) --------------------------------------------------------------------------- Star Trackers The "first generation" star trackers, e.g., the NASA-Standard Fixed-Head Star Tracker (FHST) using analog photomultiplier technology, were designed to provide peak sensor response near the visual portion of the stellar spectrum. Therefore, measured "visual" stellar magnitudes (Mv), the most commonly measured stellar spectral band, were sufficient to predict instrumental magnitudes for the FHST's. However, with the advent of charge-coupled device (CCD)-based star sensors, which characteristically have peak sensitivities biased toward the "red/infrared" portion of the stellar spectra, additional spectral data were necessary to accurately predict instrumental magnitudes. [Image] Provide us with your comments!