16 Aug 2013 C. Acton An spk for C/2013 A1, named "SIDING SPRING", was produced on Aug 16 2013 using the HORIZONS on-line ephemeris generator. That spk, with file name "siding-spring.bsp," is located in this folder. A summary of its coverage and contents made using the SPICE "brief" utility is: Body: 1003228 w.r.t. SUN (10) Start of Interval (ET) End of Interval (ET) ----------------------------- ----------------------------- 2013 AUG 01 00:00:00.000 2014 DEC 01 00:00:00.000 As seen above, the NAIF ID for this comet is 1003228. Since the association of "SIDING SPRING" with this ID has not been coded into NAIF Toolkit software, you must use this ID as the object name in calls to the spk readers.* Quite possibly you will need to load into your program a planet ephemeris spk (e.g. de430.bsp) in addition to this Siding Spring spk, unless all you need is the ephemeris of Siding Spring realtive to the sun. CAUTION: the accuracy of siding-spring.bsp will degrade quickly as time Cmoves beyond its August 16 2013 creation date. You should probably Cmake your own SPK instead of using this one; read on. If you wish to make your own SPK for C/2013 A1 (Siding Spring) using the HORIZONS ephemeris system at JPL, you can use a WWW interface (easiest) or a telnet interface: Horizons WWW interface: http://ssd.jpl.nasa.gov/x/spk.html Horizons telnet command line interface: telnet ssd.jpl.nasa.gov 6775 An example script is available at: ftp://ssd.jpl.nasa.gov/pub/ssd/smb_spk As Siding Spring has not been observed close up there are no FK or PCK data for it. * If you wish your program to be able to use 'SIDING SPRING' instead of 1003228 as the object name, you may establish this name-to-ID relationship in your own program by placing the following two lines in a text kernel that is loaded into your program. (It could be an existing text kernel, or one newly created for this purpose.) NAIF_BODY_NAME += ( 'SIDING SPRING' ) NAIF_BODY_CODE += ( 1003228 ) (You should carefully type the above lines; don't cut and paste them. Note the use of the "+=" operator instead of just an "=", and the use of the single quote characters around the name.) Read the SPICE tutorial named "08_intro_to_kernels" (especially pages 8 - 12 and page 16) to learn more about text kernels. All SPICE tutorials are available here: http://naif.jpl.nasa.gov/naif/tutorials.html Below are the comments from the SPK comment area. ----------------------------------------------------------------------- IMPORTANT NOTICE: This informal file release should not be used for purposes affecting the safety and success of spacecraft hardware or missions without first contacting Donald.K.Yeomans@jpl.nasa.gov (Supervisor, Solar System Dynamics Group, 818-354-2127) or Jon.D.Giorgini@jpl.nasa.gov (SSDG analyst). This is because an object's orbit solution may be insufficiently determined over the chosen time-span to be suitable for some high-precision purposes, due to the quantity of measurements available for an object, the time-span they cover, and the object's dynamical path. Although not stored in this file, statistical uncertainty of the trajectory as a function of time may be available from the JPL Horizons system. This can help interpret the accuracy of the trajectory. Orbit solutions are updated in Horizons as new measurements are made, so this trajectory may be superceded by more recent solutions. Check the orbit solution number for an object (given below as "source") against the latest Horizons entry to determine if an updated orbit solution is available. This parameterized post-Netwonian numerically integrated perturbed trajectory was produced by: Horizons On-Line Ephemeris System Solar System Dynamics Group Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 USA Horizons information & documentation: http://ssd.jpl.nasa.gov/?horizons Connection for small-body SPK generation (automation scripts available): telnet ssd.jpl.nasa.gov 6775 (interactive UNIX/Linux command-line) telnet://ssd.jpl.nasa.gov:6775 (interactive browser URL window) http://ssd.jpl.nasa.gov/x/spk.html (passive browser form) Inquiries: Jon.D.Giorgini@jpl.nasa.gov (program author; 818-393-3107) SPK file contents: OBJECT #01 ========== Requested by : cacton@jpl.nasa.gov Execution date : Fri Aug 16 10:00:29 2013 (Pasadena time) Target body : Siding Spring (C/2013 A1) {source: Horizons_SPK:JPL#19} Target SPK ID : 1003228 Coord center : Sun ( 10) {source: DE-0431LE-04} GM of center : 2.9591220828559109E-04 au^3/d^2 Small-body perts: Yes {source: SB431-BIG16} Start time : 2013-Aug-01 00:00:00.0000 CT Stop time : 2014-Dec-01 00:00:00.0000 CT ******************************************************************************* Initial FK5/J2000.0 heliocentric ecliptic osculating elements (au, days, deg.): EPOCH= 2456342.5 != 2013-Feb-19.0000000 (CT) RMSW= n.a. EC= 1.00039741467574 QR= 1.399528358476572 TP= 2456956.0245596212 OM= 300.9657126491508 W= 2.430253012957862 IN= 129.022782806194 Comet physical (GM= km^3/s^2; RAD= km): GM= n.a. RAD= n.a. M1= 5.2 M2= 10.4 k1= 11. k2= 5. PHCOF= .030