This directory contains SPK files archived in the MGN SPICE data set produced in 1996. These SPKs provide spacecraft trajectory determined by the MGN NAV team during mission operations. Sections below provide snippets of description extracted from SPKINFO.TXT file included in the data set and from the comments stored in the files. BVS/NAIF, January 27, 2006. ------------------------------------------------------------------- Extract from SPKINFO.TXT: These are the SP-kernels for the Magellan mission. Except for de403s.bsp, these are Magellan spacecraft ephemeris files. The file de403s.bsp is a planetary ephemeris provide for use with these Magellan spacecraft files. The spacecraft SPK files were made in reference to DE-200, but DE-403 is the best planetary ephemeris now available, and we recommend its use. There are both large and small gaps in the spacecraft data. We have only a small amount of data before the beginning of cycle 1 (September 15, 1990), which is in the file precycl1.bsp. There are four files covering cycles 1 through 6, called cycle1.bsp, cycle2.bsp, etc. There is one file covering the aerobraking phase, aerobrak.bsp. Each file has a label, which has the same name, but ends .lbl, instead of .bsp. Please see these label files for details about individual files. If this dataset was obtained on CD, there are three discs. The first disk contains all data through aerobraking, the second contains cycle5 and the third contains cycle6. Exract from comments in AEROBRAK.BSP Time Coverage Body: MAGELLAN (-18) Start of Interval (ET) End of Interval (ET) -------------------------------- -------------------------------- 1993 MAY 25 23:00:59.185 1993 AUG 16 01:01:00.182 The data was taken from pfiles from the Magellan Nav team (Kuen Wong) which were converted to SPK format. Status A SPK format archive product made from Nav pfiles. Production/History of this Ephemeris Karen Zukor read in the Nav pfiles from 8mm tape, and then combined each tape's files into one SPK file, using NIOSPK. These files were then merged with the other SPK files for the cycle with SPKMERGE. The tapes containing the pfiles were obtained from Kuen Wong. If overlapping exisited, the most recent pfile was assumed to have the best information. This file is for aerobraking. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in CYCLE1.BSP Time Coverage The above bodies are covered for: Begin Ephemeris End Ephemeris ------------------------- ------------------------- 1990 SEP 15 15:57:13.648 1990 OCT 07 13:22:41.642 1990 OCT 07 13:22:41.708 1990 OCT 26 13:41:59.381 1990 NOV 10 11:35:14.448 1990 NOV 24 08:42:07.248 1990 NOV 24 17:49:43.914 1991 MAY 16 02:05:25.718 There are gaps in the data. Here,the data was either not on the tapes given to NAIF by Magellan, or the tape was unreadable. This data is also missing from the CD set made by Peter Ford. Status An archive product of formerly SFDU-wrapped transfer format SPK files (called SPEDRs), stripped of the SFDU, converted to binary format and merged. Production/History of this Ephemeris Karen Zukor made this file from 3-4 hour SFDU-wrapped transfer format SPK files (called SPEDRs). These 3-4 hour files were copied from tape, stripped of their SFDUs, and converted to binary. Then the 3-4 hour files were combined, using SPKMERGE, into bigger files (in groups of 300, because that is the maximum number of files SPKMERGE can merge at once), and then these bigger files were combined into one file per Magellan cycle. This file is for cycle 1. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in CYCLE2.BSP Time Coverage The above bodies are covered for: Begin Ephemeris End Ephemeris ------------------------- ------------------------- 1991 MAY 15 22:10:45.717 1991 MAY 17 13:56:37.584 1991 MAY 18 02:19:46.984 1992 JAN 06 07:45:17.650 1992 JAN 14 13:54:29.717 1992 JAN 16 21:57:52.043 There are gaps in the data. Here, the data was either not on the tapes given to NAIF by Magellan, or the tape was unreadable. This data is also missing from the CD set made by Peter Ford. Status An archive product of formerly SFDU-wrapped transfer format SPK files (called SPEDRs), stripped of the SFDU and converted to binary format. Production/History of this Ephemeris Karen Zukor made this file from 3-4 hour SFDU-wrapped transfer format SPK files (called SPEDRs). These 3-4 hour files were copied from tape, stripped of their SFDUs, and converted to binary. Then the 3-4 hour files were combined, using SPKMERGE, into bigger files (in groups of 300, because that is the maximum number of files SPKMERGE can merge at once), and then these bigger files were combined into one file per Magellan cycle. This file is for cycle 2. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in CYCLE3.BSP Time Coverage Body: MAGELLAN (-18) Start of Interval (ET) End of Interval (ET) -------------------------------- -------------------------------- 1992 JAN 25 00:37:36.184 1992 JUL 02 14:58:47.117 1992 JUL 02 17:35:14.650 1992 JUL 02 21:29:53.050 1992 JUL 04 21:43:57.849 1992 JUL 05 04:54:08.916 1992 JUL 05 10:46:09.183 1992 JUL 05 14:40:47.583 1992 JUL 05 20:32:47.190 1992 JUL 06 13:29:36.183 1992 JUL 08 07:12:36.316 1992 JUL 08 14:22:47.383 1992 AUG 17 11:03:00.000 1992 SEP 15 01:00:59.182 The data was taken from two sources: original 3-4 hour SFDU- wrapped transfer format SPK files (called SPEDRs) and from pfiles from the Magellan Nav team (Kuen Wong) which were converted to SPK format. The Nav data was used to fill in gaps on the orginal SPK files. Gaps in the data remain. These were missing from both the original SPK (SPEDRs) and the Nav pfiles. This data is also missing from the CD set made by Peter Ford. The SPEDRs include data for some planets and the sun, which is included here. The pfiles were for the Magellan spacecraft only. You can tell which data is from the tapes, but looking at the coverage of the planets and sun. The remaining data is from the Nav pfiles. Status An archive product of formerly SFDU-wrapped transfer format SPK files (called SPEDRs), stripped of the SFDU and converted to binary format. Production/History of this Ephemeris 1. Processing the SPEDRs Karen Zukor made this file from 3-4 hour SFDU-wrapped transfer format SPK files (called SPEDRs). These 3-4 hour files were copied from tape, stripped of their SFDUs, and converted to binary. Then the 3-4 hour files were combined, using SPKMERGE, into bigger files (in groups of 300, because that is the maximum number of files SPKMERGE can merge at once), and then these bigger files were combined into one file per Magellan cycle. 2. Processing the Nav files Karen Zukor read in the Nav files from 8mm tape, and then combined each tape's files into one SPK file, using NIOSPK. If overlapping Nav pfile data existed, the most recent pfile was assumed to contain the best data. These files were then merged with the other SPK files from the SPEDRS with SPKMERGE. This file is for cycle 3. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in CYCLE4.BSP Time Coverage Body: MAGELLAN (-18) Start of Interval (ET) End of Interval (ET) -------------------------------- -------------------------------- 1992 SEP 13 23:00:59.182 1993 MAY 26 01:00:59.185 The data was taken from two sources: original 3-4 hour SFDU- wrapped transfer format SPK files (called SPEDRs) and from pfiles from the Magellan Nav team (Kuen Wong) which were converted to SPK format. The Nav data was used to fill in gaps on the orginal SPK files. All gaps were filled. The SPEDRs include data for some planets and the sun, which is included here. The pfiles were for the Magellan spacecraft only. You can tell which data is from the tapes, but looking at the coverage of the planets and sun. The remaining data is from the Nav pfiles. Status An archive product of formerly SFDU-wrapped transfer format SPK files (called SPEDRs), stripped of the SFDU and converted to binary format. Production/History of this Ephemeris 1. Processing the SPEDRs Karen Zukor made this file from 3-4 hour SFDU-wrapped transfer format SPK files (called SPEDRs). These 3-4 hour files were copied from tape, stripped of their SFDUs, and converted to binary. Then the 3-4 hour files were combined, using SPKMERGE, into bigger files (in groups of 300, because that is the maximum number of files SPKMERGE can merge at once), and then these bigger files were combined into one file per Magellan cycle. 2. Processing the Nav files Karen Zukor read in the Nav files from 8mm tape, and then combined each tape's files into one SPK file, using NIOSPK. If overlapping Nav pfile data existed, the most recent pfile was assumed to contain the best data. These files were then merged with the other SPK files from the SPEDRS with SPKMERGE. This file is for cycle 4. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in CYCLE5.BSP Time Coverage Body: MAGELLAN (-18) Start of Interval (ET) End of Interval (ET) -------------------------------- -------------------------------- 1993 AUG 15 23:01:00.182 1994 FEB 03 01:05:00.000 1994 FEB 03 13:39:00.000 1994 FEB 14 09:40:00.000 1994 FEB 14 12:43:00.000 1994 FEB 15 07:45:00.000 1994 FEB 15 10:46:00.000 1994 FEB 16 08:55:00.000 1994 FEB 16 11:58:00.000 1994 FEB 17 02:15:00.000 1994 FEB 17 10:01:00.000 1994 FEB 18 08:10:00.000 1994 FEB 18 20:40:00.000 1994 APR 08 08:15:00.000 1994 APR 08 11:10:00.000 1994 APR 16 01:01:00.185 The data was taken from the Magellan Nav team (Kuen Wong) which were converted to SPK format. There were some gaps in this data, as shown above. Status A SPK format archive product made from Nav pfiles. Production/History of this Ephemeris Karen Zukor read in the Nav pfiles from 8mm tape, and then combined each tape's files into one SPK file, using NIOSPK. These files were then merged with the other SPK files for the cycle with SPKMERGE. The tapes containing the pfiles were obtained from Kuen Wong. If overlapping exisited, the most recent pfile was assumed to have the best information. This file is for cycle 5. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in CYCLE6.BSP Time Coverage Body: MAGELLAN (-18) Start of Interval (ET) End of Interval (ET) -------------------------- ----------------------------- 1994 APR 15 23:01:00.185 1994 OCT 14 01:01:01.182 The data was taken from the Magellan Nav team (Kuen Wong) which were converted to SPK format. Status A SPK format archive product made from Nav pfiles. Production/History of this Ephemeris Karen Zukor read in the Nav pfiles from 8mm tape, and then combined each tape's files into one SPK file, using NIOSPK. These files were then merged with the other SPK files for the cycle with SPKMERGE. The tapes containing the pfiles were obtained from Kuen Wong. If overlapping exisited, the most recent pfile was assumed to have the best information. This file is for cycle 6. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403. Exract from comments in DE403S.BSP Ephemeris DE403s 14-NOV-1995 Objects In This Ephemeris Name Id-code ------------------------------------ Sun...............................10 Mercury Barycenter.................1 Mercury..........................199 Venus Barycenter...................2 Venus............................299 Earth Moon Barycenter..............3 Moon.............................301 Earth............................399 Mars Barycenter....................4 Mars.............................499 Jupiter Barycenter.................5 Saturn Barycenter..................6 Uranus Barycenter..................7 Neptune Barycenter.................8 Pluto Barycenter...................9 Time Coverage The approximate time coverage for the bodies listed is: From: December 1, 1979 To : January 7, 2011 Status This ephemeris is a time subset of the JPL planetary ephemeris DE403. All of the bodies whose positions are modelled by DE403 are included. However, in order to make a reasonably compact ephemeris, only that portion of the ephemeris for the time span indicated above is included. The full DE403 ephemeris covers the interval from 29 April 1599 to 1 February 2200. As of November 13, 1995 this is the official ephemeris planned for use by the flight projects: Cassini, Mars Pathfinder, Mars Global Surveyor, Near Earth Asteroid Rendezvous. Note: This ephemeris is not suitable for use by those processing or using Galileo data. This is the latest and most accurate ephemeris distributed by JPL for the planets, sun and moon. We note that "formally" the positions of Mercury, Venus and Mars are not present in DE403. However, we have included these objects in this SPK file and set the offsets from to their respective system barycenters to zero. Mercury and Venus have no satellites. Consequently the system barycenters and centers of the bodies coincide. In the case of Mars, the offset of Mars from the Mars system barycenter cannot be detected with current technology. Moreover, simple calculations show that this offset can never exceed more than 10 cm. For this reason we include Mars with a zero offset from the system barycenter. Production/History of this Ephemeris This is a time subset of the full ephemeris DE403 which spans the time interval from 1599 APR 29 to 2200 FEB 01. This ephemeris represents an improvement over previous JPL planetary ephemerides. We reiterate some of the features of DE403 that are listed in the JPL Interoffice Memorandum listed in the "References" section below: -- The ephemeris is now based upon the J2000 reference frame of the International Earth Rotation Service (IERS). -- The standard sets of observations have been augmented with more recent observations. -- A number of new data types have been added to the observational data set. -- Some of the data reduction techniques have been refined. -- The modeling of the perturbations of asteroids upon the planetary orbits has been improved. The full DE403 ephemeris corrects a number of problems that have been identified for the moon prior to 1750 in the ephemeris DE118 . This SPK file was created from the JPL planetary ephemeris DE403 on June 1, 1995 by Hester Neilan of NAIF. It was created using the following script run by the NAIF program NIOSPK. ; de403s.bsp LOG FILE ; ; Created 1995-06-01/12:14:42.00. ; ; BEGIN NIOSPK COMMANDS LEAPSECONDS_FILE = /naif/data/naif0004.tls SPK_FILE = de403s.bsp SPK_LOG_FILE = de403s.log SOURCE_NIO_FILE = de403s.nio BODIES = 1 2 3 4 5 6 7 8 9 10 301 399 199 299 499 BEGIN_TIME = 1979 NOV 30 23:59:09.8169231 END_TIME = 2011 JAN 06 23:58:58.8159093 ; END NIOSPK COMMANDS Usage This ephemeris is suitable for use with the projects listed above and for general planning of terrestrial or satellite based observations of the planets and moon. However, satellites of planets, asteroids and comets are not provided in this ephemeris. Ephemerides for these objects may be obtained by contacting NAIF via the phone numbers or e-mail addresses listed below. Accuracy The JPL "DE" series of planetary ephemerides have been widely used throughout the astronomical community for over 20 years. They have been put to many different uses. A short list of the applications of these ephemerides includes: the construction of the tables in the "Astronomical Almanac" (for that matter all almanac producers world wide), planning of solar system observations with the Hubble Space Telescope, navigation of interplanetary missions, lunar laser ranging, solar system radar ranging, and solar system observations via VLBI. This latest ephemeris, DE403, represents state-of-the-art planetary and lunar positions. One method of describing the accuracy of the positions provided in DE403 is to consider the angles between various ephemeris objects as viewed from Earth. If the two objects observed are taken from the list (Sun, Mercury, Venus, Mars, Moon) the angles computed from the ephemeris positions are accurate to one or two milli-arcsecond.(This assumes all appropriate corrections are applied for light time, stellar aberration, and relativistic effects to the ephemeris derived positions.) If you add the barycenter of Jupiter to this list, uncertainty in ephemeris derived angles may grow to a few hundredths of an arcsecond. Adding Saturn, Uranus and Neptune will raise the uncertainty level to approximately 0.1 arcseconds. Finally, adding Pluto to the list raises the observable errors to 0.3 arcseconds for the present and increasing into the future. Radial distances to the centers of objects follow a similar trend. The radial distances between the inner objects of the solar system as computed via the ephemeris are accurate to 1 to 2 km. The distance between the Earth and the Jupiter Barycenter is accurate to better than 10 km. The uncertainty in the distances to Saturn, Uranus and Neptune are approximately 1000, 2000 and 4000 km respectively. For Pluto, the radial distance from earth may be in error up to 10000 km for the present and growing into the future. The above statements refer to the internal consistency of the ephemeris. These statements of accuracy also hold when comparing positions with the J2000 radio source reference frame adopted by the IAU and IERS. When comparing the position a planet (other than Pluto) as seen from earth with catalogue positions of stars, the DE403 positions of the planets are very likely to be more accurate than knowledge of the positions of the stars in the catalog (with the possible exception of the Hipparchos catalog). In the case of Pluto, the error in the DE403 position of Pluto is likely to be close to the error in the catalogue positions of stars. References Jet Propulsion Laboratory Interoffice Memorandum IOM 314.10-127 by E.M. Standish, X.X. Newhall, J.G. Williams and W.M. Folkner "JPL Planetary and Lunar Ephemerides, DE403/LE403" Exract from comments in PRECYCL1.BSP Time Coverage The above bodies are covered for: Start of Interval (ET) End of Interval (ET) -------------------------------- -------------------------------- 1990 AUG 16 21:59:22.248 1990 AUG 17 11:41:48.648 This was the only SPK type data found for any pre-cycle 1 time period. Status An archive product of formerly SFDU-wrapped transfer format SPK files (called SPEDRs), stripped of the SFDU, converted to binary format and merged. Production/History of this Ephemeris Karen Zukor made this file from 3-4 hour SFDU-wrapped transfer format SPK files (called SPEDRs). These 3-4 hour files were copied from tape, stripped of their SFDUs, and converted to binary. Then the 3-4 hour files were combined, using SPKMERGE, into this file. This file is for the pre-cycle 1 time period. This file was made by Karen Zukor in August 1996. Usage This file was made in reference to DE-200. However, it can be used with the improved planetary ephemeris DE-403.