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Phase2 UI: Ephemeris Table Input

This page tells you how to input ephemeris tables into the Phase 2 UI and what formats to use. Although ephemeris tables can be generated by any method you choose, we use the tables produced by JPL HORIZONS (JPLH) in our examples further down the page.

Required Ephemeris Format


The phase 2 UI requires ephemeris data in this format (comma or whitespace delimited):

yyyy-mm-dd hh:mm hh mm ss ±dd mm ss n.nn n.nn
(|--date--| time |--RA--| |--DEC--| dRA dDEC)

where date & time are in UT, and:

  • RA = Right Ascension (J2000)
  • DEC = Declination (always with sign) (J2000)
  • dRA = RA rate of change in arcsec/hour
  • dDEC = DEC rate of change in arcsec/hour

Note also that:

  • RA & DEC must be topocentric coordinates for the specified time at the LT site location.
  • dRA & dDEC are currently not used by the robotic control system, it derives a rate by interpolating the positions. However the rates must currently be specified.

Examples of both comma and whitespace delimited ephemerides:

Comma-separated variables (CSV) format:
2009-Nov-04 21:00, , ,04 32 01.37,+24 55 28.3, 2077.870, 525.5907
2009-Nov-04 21:15, , ,04 32 39.10,+24 57 39.9, 2028.686, 522.1528
2009-Nov-04 21:30, , ,04 33 15.94,+24 59 50.4, 1979.719, 517.3850
2009-Nov-04 21:45, , ,04 33 51.89,+25 01 59.5, 1931.170, 511.2841
2009-Nov-04 22:00, , ,04 34 26.97,+25 04 06.9, 1883.238, 503.8527
2009-Nov-04 22:15, , ,04 35 01.18,+25 06 12.3, 1836.125, 495.0990
2009-Nov-04 22:30, , ,04 35 34.54,+25 08 15.3, 1790.027, 485.0375
2009-Nov-04 22:45, , ,04 36 07.08,+25 10 15.6, 1745.143, 473.6886
2009-Nov-04 23:00, , ,04 36 38.81,+25 12 13.0, 1701.665, 461.0789
2009-Nov-04 23:15, , ,04 37 09.76,+25 14 07.0, 1659.782, 447.2412
2009-Nov-04 23:30, , ,04 37 39.96,+25 15 57.4, 1619.677, 432.2145
Whitespace-separated format:
2009-Jul-30 00:00 08 35 45.57 +01 38 09.9 4.145303 -1.02806
2009-Jul-31 00:00 08 35 52.21 +01 37 45.0 4.143384 -1.04952
2009-Aug-01 00:00 08 35 58.84 +01 37 19.7 4.140392 -1.07069
2009-Aug-02 00:00 08 36 05.46 +01 36 53.8 4.136340 -1.09158
2009-Aug-03 00:00 08 36 12.08 +01 36 27.4 4.131236 -1.11218
2009-Aug-04 00:00 08 36 18.69 +01 36 00.6 4.125087 -1.13250
2009-Aug-05 00:00 08 36 25.29 +01 35 33.2 4.117899 -1.15254
2009-Aug-06 00:00 08 36 31.87 +01 35 05.4 4.109676 -1.17229
2009-Aug-07 00:00 08 36 38.45 +01 34 37.1 4.100419 -1.19176

Note the RCS ignores columns 2 & 3 of CSV data, which sometimes contain sun and moon presence indicators, but at other times are blank. They are always output by JPLH. If you select non-CSV output these indicators will need to be manually edited out. However, their interm2ittent presence makes this task monotonous and time-consuming, and for this reason we strongly advise users to always select CSV format if at all possible.

Settings to use with JPL Horizons


The following summarizes the options to select on the JPLH web interface to ensure the output table is in the correct format for the RCS

  • Set ephemeris type = OBSERVER
  • Select your target body
  • Set observer location = [J13] La Palma - Liverpool Telescope.
  • Set time span as you wish, but a minimum interval of 5 mins is recommended.
  • Select Table Settings:
    • enter the Table Settings page
    • set the "preset observer quantities selection" to "None" at first to erase the default settings
    • select "astrometric RA, Dec" (quantity 1) and "RA,Dec rates" (quantity 3) only
    • select the tick box for "CSV format" near the bottom of the page
  • Set Display/Output = "plain text" or "download/save", whichever you wish.

Only copy & paste the output table of time,RA,dec,rates into the Phase2UI dialogue box, not the headers and comments.

An example of how the Horizons config page looks for a successful table generation:

Non-CSV format


If building a table by hand it is probably easier to use the non-CSV format. Note that Horizons can also generate a non-CSV table but if you choose to do this you must manually edit out the LUNAR and SOLAR alphabetic flags which sometimes appear in the column between the time and RA.

Using Microsoft Windows


If you are using a Windows machine, then For the Display/Output selection, we recommend using the "download/save" option. This will download a text file containing the ephemerides directly from the web-server. This file can then be opened with a text editor, and the required section copied and pasted into the text area. We recommend using Notepad to open this file (rather than, for instance Wordpad), due to the way line-breaks are handled differently between the applications.