catalog filename
Load sources from a source catalog file.
InputFile filename
~mcs/CBI/ephem/source.cat to the current source
catalog. New sources with the same names as ones that are
already in the catalog replace the old ones.
catalog ~mcs/CBI/ephem/source.cat
#
character and extend to the end of the line. The following
example would be valid as a source catalog, and shows examples of
all the supported syntax:
# This is a comment. #----------------------------------------------------------------------- # The following entry describes a source called "alyr" by its # J2000 Right Ascension, Declination, and its J2000 proper motion # per Julian year in Right Ascension and Declination. # # Source Equatorial position Proper motion/yr # RA Dec RA Dec # type name hh:mm:ss.sss dd:mm:ss.ss h:m:ss.ssss d:m:ss.sss #----------------------------------------------------------------------- J2000 alyr 18:35:14.655 38:44:09.68 +0:0:00.0170 +0:0:00.285 #----------------------------------------------------------------------- # The following entry describes a J2000 source with no proper motion. # # Source Equatorial position # RA Dec # type name hh:mm:ss.sss dd:mm:ss.ss #----------------------------------------------------------------------- J2000 0003-066 00:03:40.290 -06:40:17.60 #----------------------------------------------------------------------- # The following entry defines "vega" as an alternate name for "alyr". # # type name existing name #----------------------------------------------------------------------- alias vega alyr #----------------------------------------------------------------------- # The following entry defines the local zenith in terms of fixed # telescope axis positions. # # type name azimuth elevation deck-angle #----------------------------------------------------------------------- FIXED zenith 0 90.0 0 #----------------------------------------------------------------------- # The following entry defines the sun as a source who's equatorial # position is defined by the contents of an ephemeris file. # # type name ephemeris-file #----------------------------------------------------------------------- EPHEM sun ~mcs/CBI/ephem/sun.ephem
#----------------------------------------------------------------------- # CBI Ephemeris for Mars # # Note that TT ~= TAI + 32.184. # See slaDtt.c for how to convert TT to UTC. # # Also note that MJD = JD - 2400000.5 # # MJD (TT) Right Ascen Declination Distance (au) Calendar (TT) #--------- ------------- ------------- ------------ ----------------- 50814.0000 20:54:12.9302 -18:39:22.171 2.1366386049 # 1998-Jan-01 00:00 50815.0000 20:57:24.0642 -18:26:03.652 2.1398752328 # 1998-Jan-02 00:00 50816.0000 21:00:34.7660 -18:12:33.346 2.1431046252 # 1998-Jan-03 00:00 50817.0000 21:03:45.0305 -17:58:51.438 2.1463269705 # 1998-Jan-04 00:00Note that comments are introduced with the '
#' character
and they extend to the end of the containing line.
The CBI ephemerides were produced as follows. JPL provides an E-mail
service for generating ephemerides. For each source of interest one
submits a batch-job file via E-mail and a few minutes later receives
one or more automated replies containing the requested ephemeris
entries. One then has to remove the E-mail headers, splice the E-mails
together in the correct order and then apply the following awk script
to the result to produce the CBI ephemeris of the source. Note that
the comments in the header of the script also outline the details of
the batch file and its submittal.
#!/bin/nawk -f
#-----------------------------------------------------------------------
# Convert the format of an E-mailed JPL ephemeris to a machine readable
# form. To have a new ephemeris sent by JPL, change the COMMAND, START_TIME,
# STOP_TIME and STEP_SIZE parameters of the following, remove the initial
# # characters and E-mail the result to horizons@ssd.jpl.nasa.gov, along
# with the subject line: JOB-SUBMITTAL
#
#!$$SOF (ssd) JPL/Horizons Execution Control VARLIST July, 1997
# EMAIL_ADDR = mcs@astro.caltech.edu
# COMMAND = 'mars'
# OBJ_DATA = NO
# MAKE_EPHEM = YES
# TABLE_TYPE = OBS
# CENTER = GEO
# COORD_TYPE = GEODETIC
# SITE_COORD = '0,0,0'
# START_TIME = '1997-JAN-1 00:00'
# STOP_TIME = '1998-JAN-1 00:00'
# STEP_SIZE = '1 days'
# QUANTITIES = '2,20'
# REF_SYSTEM = J2000
# CAL_FORMAT = BOTH
# ANG_FORMAT = HMS
# APPARENT = AIRLESS
# TIME_TYPE = TT
# ELEV_CUT = -90
# SKIP_DAYLT = NO
# AIRMASS = 38.D0
# EXTRA_PREC = YES
# CSV_FORMAT = NO
#!$$EOF+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#
#-----------------------------------------------------------------------
# The following variable will be 1 until the start of the ephemeris
# is seen. This allows for rejection of lines of the header section
# that might otherwise be interpreted as ephemeris entries.
BEGIN {
in_header=1
}
# Get the name of the target planet from the header.
/^Target body/ {
printf("# CBI Ephemeris for %s\n", $4);
}
# The following pattern matches the start of the ephemeris table.
/^\$\$SOE/ {
# Signal that we have finished reading the header section.
in_header=0;
# Describe the contents of the file.
printf("#\n");
printf("# Note that TT ~= TAI + 32.184.\n");
printf("# See slaDtt.c for how to convert TT to UTC.\n");
printf("#\n");
printf("# Also note that MJD = JD - 2400000.5\n");
printf("#\n");
printf("# MJD (TT) Right Ascen Declination Distance (au) Calendar (TT)\n");
printf("#--------- ------------- ------------- ------------ -----------------\n");
}
# Output reformatted ephemeris lines.
/^ [0-9]/ && !in_header {
printf("%.4f %s:%s:%s %s:%s:%s %s # %s %s\n",
$3 - 2400000.5, $4,$5,$6, $7,$8,$9, $10, $1, $2);
}
# The job is complete when the end of the ephemeris table is reached.
/^\$\$EOE/ {
exit
}
For the standard solar system objects I used that the following
values for the COMMAND and STEP_SIZE parameters.
COMMAND STEP_SIZE Sun 'sun' '1 days' Mercury 'mercury' '12 hours' Venus 'venus' '1 days' Moon '301' '6 hours' Mars 'mars' '1 days' Jupiter Barycenter '599' '1 days' Saturn Barycenter '699' '1 days' Uranus Barycenter '799' '1 days' Neptune Barycenter '899' '1 days' Pluto Barycenter '999' '1 days'Note that JPL says that the batch program may change over time, so be prepared for the above procedures to need some adjustments. The example batch file that they provided me with listed the following options for requesting up to date information about their "Horizons" facility. Simply send an empty E-mail to horizons@ssd.jpl.nasa.gov with one of the following subjects:
HORIZONS-BATCH-LONG (Request latest fully commented example batch file) HORIZONS-BATCH-BRIEF (Request latest example batch file without comments) HORIZONS-DOC-TEXT (Request ASCII version of current documentation) HORIZONS-DOC-PS (Request PostScript version of current documentation) HORIZONS-QUESTION (Message fowarded to cognizant engineer)You can also invoke an interactive session by typing:
telnet ssd.jpl.nasa.gov 6775Or by accessing http://ssd.jpl.nasa.gov/cgi-bin/eph with a Web browser.