If your telescope supports offset tracking rates, be sure to look at the #TRACKON and #TRACKOFF plan directives. These control ACP's orbital tracking feature, where the motion of the minor planet is fed into the telescope and its tracking is adjusted to match the motion. An orbitally tracked image will show trailed stars and a stationary minor planet.The formula for calculating the position of a minor planet changes over time, so orbital elements are themselves calculated for a particular epoch. If you are tracking a minor planet, you should update your orbital elements (or MPCORB.DAT) periodically. There's no set formula for how often to do this. Orbits vary, the orbit may be "improved" via additional observations, the orbit may be perturbed by a large body, etc.
Newly discovered near-earth orbit (NEO) asteroids may not have elements available. They may be listed on the Near Earth Asteroid Confirmation Page (NEOCP), however, in the form of ephemerides. ACP can also handle targets composed of multiple NEOCP ephemeris records. See NEO Ephemerides.
ACP accepts minor planet orbital elements in the Minor Planet Center "1-line" format or just the designation (numbered, named, packed or unpacked provisional, see the info on MPCORB below). To get this information directly from the Minor Planet Center's web site (as opposed to a local MPCORB database), first prepare a list of targets you want to image by designation or name. Designations should be entered in one of the following forms:
Designations are case sensitive. Once you have this list, go to the Minor Planet Ephemeris Service web page. Enter your objects as above into the list area. You can leave the Ephemeris Options section blank, as you are not getting an ephemeris. Make sure you select "MPC 1-line" for the return format, as shown in the image to the right. You will be prompted to save a file called "elements.txt" (or possibly "elements.txt.COM"), save the file with the name you wish, and an extension of ".txt".
The format of the MPC 1-line elements is shown in the table below:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
50000 2.4 0.15 K134I 276.47478 162.95152 188.95990 7.99306 0.0364151 0.00347369 43.1792876 1 MPO235046 393 19 1954-2012 0.31 M-v 38h MPC 0000 (50000) Quaoar 20120217
52747 7.9 0.15 K134I 307.90615 251.35770 63.92318 0.54435 0.0571554 0.00335046 44.2316311 3 MPO 66038 22 6 1998-2004 0.23 M-v 38h MPC 0000 (52747) 1998 HM151 20040527
K01FI5V 7.7 0.15 K014L 0.10308 171.64687 13.10223 24.22357 0.1253747 0.00398842 39.3793664 E MPO 14427 4 1 57 days 0.37 Marsden 0000 2001 FV185 20010522
K01FJ3K 6.9 0.15 K134I 74.19379 50.34129 89.85793 3.51502 0.0672630 0.00338330 43.9449692 4 MPO 48027 12 3 2001-2003 0.20 M-v 38h MPC 0000 2001 FK193 20030430
23257 14.9 0.15 K134I 53.43743 113.38101 307.03990 5.72310 0.1116163 0.24385827 2.5373345 0 MPO250439 371 13 1993-2013 0.49 M-v 38h MPC 0000 (23257) Denny 20130106
The MPC furnishes elements in a number of formats used by other software, however ACP uses the standard MPC format. ACP is compatible with the new encoded numbering format used for asteroids with numbers 100000 and greater.
If you want to download the elements database from the Minor Planet Center (MPCORB.DAT), ACP can automatically retrieve elements locally, then calculate position and motion. In the folder
C:\Program Files (x86)\Common Files\ASCOM\MPCORB there is a set of tools for building a fast-lookup database from MPCORB.DAT. Instructions are in the readme.txt file there. If you build the database as instructed, you need only give "MP " plus the designation (numbered, named, packed or unpacked provisional) as a target specification. ACP uses the MPCORB database wrapper object to retrieve the elements. It is very fast!If you built the local MPCORB database as described in the note above, you need only give "MP " (note the space after MP) and the designation. If you use a (numbered) minor planet number, you must give all 5 digits, including leading zeroes if necessary. For example:
MP 12000 ; or 1996 CK2
MP 2000 YX26 ; or K00Y26X
MP Denny ; or 23257The MPC format of comet elements is shown in the table below.
0 1 2 3 4 5 6 7 8 9 0 1 2 3
1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
-------------------------------------------------------------------------------------------------------------------------------------------
0009P 2005 07 5.4585 1.504580 0.517665 178.8975 68.9734 10.5341 20030610 5.5 10.0 9P/Tempel 1
0029P 2004 07 16.7492 5.723075 0.044484 49.3869 312.7241 9.3938 20030610 4.0 4.0 29P/Schwassmann-Wachmann 1
PJ97T030 1998 03 9.3751 4.254196 0.363493 334.4067 63.2120 4.8348 20030610 13.0 2.0 P/1997 T3 (Lagerkvist-Carsenty)
CK02E020 2002 02 21.7373 1.466476 1.000360 9.0232 244.5739 92.5480 20030610 7.5 4.0 C/2002 E2 (Snyder-Murakami)
If you built the local MPCCOMET database as described in the note above, you need only give "CT " (note the space after CT) and the designation or name. If you use a (numbered) comet number, you must give all 5 digits, including leading zeroes if necessary. For example:
CT 0244P ; or 244P/Scotti
CT CK12J010 ; or C/2012 J1Note that for unnumbered comets, the comet name does not include the name part within the parentheses, which in the above example second line would be (Catalina). Do not include this part in the name given on the target line.