Click here for an explanation of what this page is and why it exists, and for links to related tools.
Cut and paste astrometry in the MPC's 80-column astrometric reporting format and/or in ADES format (PSV and/or XML), and click 'Process observations'. The program will figure out which GNSS satellite(s) you observed and tell you how far off you were in along-track seconds and cross-track arcseconds, for each observation. (The object designations can be anything you like; they'll be ignored.) At the bottom, you'll get averages and standard deviations.
The 'relocation' allows you to set a specific latitude, longitude, and altitude for your observatory. The position specified by the MPC will be ignored, and the position you specify used instead. You have to specify latitude/longitude with compass signs. Don't use + and -; '+31.4159' could be a north latitude or an east or west longitude. Compass signs are unambiguous. The values must be separated by commas. The altitude must be followed by 'm' for meters or 'ft' for feet.
The example position is for the 2.2-meter scope on Mauna Kea, which is about 19.8 degrees above the equator and 155.4 degrees West longitude. The altitude is above the ellipsoid, not above sea level. (This can make a difference of up to about a hundred meters in some parts of the world.)
Also note that you can send me your exact telescope location, and I'll add a 'non-standard' MPC code for you. (This is a list I maintain of observatories not found in the MPC file, or with incorrect or imprecise coordinates in that file.) You can then use that non-standard code here and in Find_Orb.
There are several other tools for asteroid observers on this site, including a tool to list GNSS satellites visible from a given site and a tool to generate ephemerides for a given satellite.
Usually, you can just cut-and-paste astrometry into the above form, click 'Process Observations', and you'll get back data on how good your timing was. The precision of the times in the MPC's optical observation format is a millionth of a day, or 86.4 milliseconds. For most people, that's enough precision.
But it's not enough for everybody. Somewhat to my surprise, I've encountered situations where people are testing timing down to the ten-millisecond level. If you're one of them, you'll have to go beyond the MPC's format.
There are two different ways to do so. You can provide data in the new ADES format, in either XML or PSV format. Click here for details on astrometric data formats accepted by this tool.
If you aren't ADES-ready yet, you can just modify the date/time shown in the MPC formatted record to include extra precision. Click here for an example of extended-precision observations. Here's the first observation in that example, shown first in the way MPC would expect (to six decimal places in the day) and then to nine places, and finally in hour/minute/second form to millisecond precision. Note that because all the data has to fit in the columns assigned for the date/time, spaces and colons get squeezed out.
NAVST43 C2011 10 26.81807021 18 13.88 +13 00 09.1 12.8 V Ce1
NAVST43 CK111026.81807023021 18 13.88 +13 00 09.1 12.8 V Ce1
NAVST43 CK111026:19380126821 18 13.88 +13 00 09.1 12.8 V Ce1
These all refer to the time 2011 October 26.818070230 = 2011 Oct 26 19:38:01.268 UTC. The Minor Planet Center will accept only the first of these, rounded to the nearest millionth of a day. This tool, and others on this site, will accept any of the three formats.
I can be reached at pоç.ötŭlpťсéјôřp@otúlm. If you're a human instead of a spambot, you can probably figure out how to remove the diacritical marks...