Creating Target Lists for SOAR

Target List

NOTE: Because of damage to the elevation encoder which happened during the January 2019 earthquake, SOAR has a reduced elevation limit of 79 deg. Make sure your targets remain below 79 deg elevation during your observations.

SOAR has the capability to guide sidereally or non-sidereally.

For sidereal guiding, target lists should be created as simple ASCII files with the following format:


There should be no spaces in the OBJECT_ID field. Use spaces to separate fields. Also, avoid special characters like "." or "*" in object names.

Here is a sample target list in the SOAR format:

 [1]IC418  05:27:28.20  -12:41:50.3  2000.0  V=13
 [2]IC2448  09:07:06.26  -69:56:30.6  2000.0  B=11.1
 [3]NGC3918  11:50:17.73  -57:10:56.9  2000.0  V=8.5

With this syntax, you can then just communicate to the Telescope Operator the running number of your next target.
Note that after the epoch field you can add more informational columns, which will be ignored by the Telescope Control System (TCS).

For non-sidereal guiding, our software is set up to read in ephemerides generated using horizons ( An example of this is given below:

 #Date__(UT)__HR:MN R.A.___(ICRF/J2000.0)___DEC dRA*cosD d(DEC)/dt a-mass
 2008-Apr-07 05:00  16 44 46.1498 -01 44 13.359  -2.87  2.01  1.793
 2008-Apr-07 05:30  16 44 46.0540 -01 44 12.353  -2.88  2.01  1.560
 2008-Apr-07 06:00  16 44 45.9578 -01 44 11.346  -2.89  2.01  1.402
 2008-Apr-07 06:30  16 44 45.8614 -01 44 10.340  -2.90  2.01  1.292
 2008-Apr-07 07:00  16 44 45.7646 -01 44 09.334  -2.91  2.01  1.217
 2008-Apr-07 07:30  16 44 45.6677 -01 44 08.328  -2.91  2.01  1.169

In order to obtain the proper information for the non-sidereal guiding ephemerides, you will want to change the Table Settings  on the Horizons webpage so that only "Astrometric RA & DEC", "Rates; RA & DEC", and "Airmass".  You will also want to change the Display/Output on the Horizons webpage to "download/save". Rates should be in arcsec/hour.

Important Note - the maximum non-sidereal rates at which the telescope can track are determined by low-level software. The maximum rate in declination is ±2700 arcsec/hour and the maximum rate in right ascension is ±180 seconds of RA/hour. This specification for the RA rate limit means that the maximum RA rate in seconds of arc/hour on the sky is 2700*cos(declination).

One can also determine which solar system objects are observable at SOAR for a given time using the JPL website (  You only need to set the observation time, location (SOAR is I33), and a limiting magnitude.  Press "search" and it will return a list of small bodies that are observable that night.  Please note that all times are UT.

Updated on July 12, 2022, 7:09 am