To download an ephemeris for a minor planet or comet and calculate its position, speed and direction of motion:

Step 1. Enter an observatory code (once only)

The application needs a valid 3-character code Minor Planet Center Observatory Code so that topocentric ephemerides can be requested from the MPES, NEOCP, Scout and Horizons web services. The code is retained and does not need to be re-entered unless ephemerides for a different location need to be generated. See Obs code for more information.

Step 2. Enter an object designation

Enter the ID of either an already designated object (e.g. a numbered or provisionally designated minor planet or comet), or temporary designation of a NEOCP object. Press the drop-down arrow to select from a list of current NEOCP objects (internet connection required). See Object for more information.

Step 3. Enter a date and time

Enter the date and time to calculate position and motion details for. There are separate areas for Year and Month, then Day, Hour, Minute and Second. See Date, time for more information.

Step 4. Generate an ephemeris (internet connection required)

Press the Retrieve MPES ephemeris or the Retrieve Horizons ephemeris button if an already designated object was entered in step 2, or the Retrieve NEOCP ephemeris or Retrieve Scout ephemeris button if a NEOCP temporary designation was entered in step 2. The downloaded ephemeris information will be displayed in the scrollable Ephemeris lines area of the Ephemeris Interpolator.

Step 5. Calculate the position and motion information for the date and time entered in step 3.

Press the Calculate button to display the RA, Declination, Speed and P.A.° for the date and time entered. Repeat step 5 with different dates and times as needed.

As an example, the following entries were made:

Step 1. Observatory code J95 entered

Step 2. Minor planet designation 2022 CA entered

Step 3. Date/time 2022 02  03  22  17  23 entered (i.e. 2022-Feb-03 22:17:23 UTC)

Step 4. The button was pressed to download an MPES ephemeris. The first 3 lines of the downloaded ephemeris lines can be seen

Step 5. The Calculate button was pressed causing the interpolated RA, Dec, Speed and P.A.° to be displayed as highlighted below.

       RA = 10h 22m 33.91s, Dec = +25° 27' 10.0", Speed = 7.48 arcsec/min, P.A. = 37.8°

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