TCS3 - Telescope Control System 3
NASA InfraRed Telescope Facility(IRTF), Institute for Astronomy, University of Hawaii

HTOOL - HORIZONS TOOL

1. HTOOL is simple application to query for JPL Horizons ephemeris data, and issue NEXT or NS.RATE (nonsidereal rates) command to TCS3.
And updates rates to the guider.

    To start htool, type 'htoolgui' in a terminal.
    Here is the user's guide: htoolgui.pdf.

2. Before using htool you will need the target ID for your object.

    Major Bodies - Planets, natural satellites, or the Sum
      You will need the JPL ID ( for example, 499 is Mars CENTER ) Used the web to query horizon for the JPL ID, use this Major Body Cheat Sheet .
      Or look here: List of Major Body Ephemerides (JPL documentation).

      Here is an example using Geodetic/planetodetic coordinates: g:E.long,latitude,h@BODY

            g:348.8,-43.3,0@301           # The Moon at Log=348.8 Lat=-43.0, Alt=0
      		

    Small Bodies - comments or asteroids

      Small bodies can be found using it's IAU ID number following the ';'. For example '1;' is Ceres (as oppose to '1' for venus).

      Use the web inteface to lookup the recorded number for your small body. Then use the IAU ID or unique designation (ie: "2015 MH10" )with htool.

    Small bodies with Numbers

      For numbered asteroids (1 to 100000), enter the record # followed by ';'.
      the record# is equal to the asteriod#, so '10000;' would be 'Asteroid 10000 Myriostos (1951 SY)'.

    Small bodies without Numbers

      For an asteroid without a JPL record# use its name, for example '2002 VT57' Note, the name are case senitive and have embedded spaces. You can o confirm the name via the web interface, then use it in htool.

      For example, for comet 27P, this query will fail, but look at the raw data. It may show something like:
      *******************************************************************************
      JPL/DASTCOM            Small-body Index Search Results     2021-Nov-02 14:17:11
      
       Comet AND asteroid index search:
      
          DES = 27P;
      
       Matching small-bodies: 
      
          Record #  Epoch-yr  >MATCH DESIG<  Primary Desig  Name  
          --------  --------  -------------  -------------  -------------------------
          90000377    1818    27P            27P             Crommelin
          90000378    1873    27P            27P             Crommelin
          90000379    1928    27P            27P             Crommelin
          90000380    1956    27P            27P             Crommelin
          90000381    1984    27P            27P             Crommelin
          90000382    2013    27P            27P             Crommelin
      
      Try the "DES=27P; CAP;" format for "closest apparition solution" for Comets that may have multiple records in the database. Ref: 190205-jpl_email.html.
      "90000382;" can be used.
3. Importing data into Horizons
    Importing Horizon data into HTOOL - If all else fails, you can lookup JPL Horizons ephemeris in a web browser, and import the results into htool. This link provides instructions on importing saved Horizon output into HToolGUI.
    You can also make simple text file you can import into htool: import_simple_txt.html

References

    major_body.html Major Body Cheat Sheet
    Horizons Web Site
    App (or query page)
    Manual (online only)