Conversion to New Format

Conversion to New Format

An important aim in the conversion process is the addition of useful information that was never recorded on the observational record or that was removed before the observations were filed. The information that should be recorded includes the reference catalogue used for the reductions, the telescope used and (where appropriate) the program code. The first and last items have been recorded or retained on the observational record in recent years but the aim is to get all three pieces of information recorded on the bulk of the more than 19 million astrometric observations currently in the MPC archive. This has necessitated, for example, the manual examination of printed copies of the MPCs spanning (as of Aug. 18) 1978 to 1991, and entering details of program codes and telescopes into a datafile for use by conversion process (sometimes having to differentiate between observations of the same object made on the same night at the same observatory by three different observing programs!). This has been tedious in the extreme. As of late on Aug. 18, a newly-written computer program is doing some preliminary scanning of the input files for the 1992 through 1997 batches of MPCs. (With a slight modification to cope with the B1950.0-format observations, it will also pre-process the small number of the remaining unprocessed 1991 batches.) These preliminary scans require manual editing and this has been completed as far as (as of Aug. 31) late-1995 batches of MPCs. The processing of the MPS batches is complicated because we don’t archive an ASCII version of this journal, so we will have to dig the ASCII text out of the DVI file. (This is actually quite difficult to do if one wishes to extract some semblance of the original layout, and initial attempts have been only semi-successful.) Once extracted, the resulting file should be able to be run through the above-mentioned program.

How observers can help

The datafiles are available from the CF’s ftp site:

These datafile will be updated on an irregular basis as observers report corrections or additions. The telescope datafile has been constructed from examining the observational headers from just two batches of MPCs: it is expected that there will be a large number of additions (and some corrections) required.

Adding/editing a telescope code

The format of the line(s) in the message should match the format of the on-line datafile. Columns 1-3 contain your observatory code. Column 6 contains the telescope identifier (first telescope = ‘1’, second = ‘2’, etc.): use the next available identifier. The telescope descriptor then begins in column 9. When describing the telescope, be consistent with the form of the existing entries. Note that apertures are generally given to 2 d.p. (e.g., 0.30-m instead of 0.3-m) and that focal ratios are not given for Schmidt-Cassegrain telescopes.

Adding a catalogue code

There is no specific format required for submission of a new catalogue code. You can request multiple catalogue code additions in the same e-mail. The four-character hex catalogue code (shown in columns 1-4) will be assigned by the MPC.

If you are lucky, you will only have to submit one line of OSI. This will be case if you have only ever observed at one site, used one telescope and reduced your observations with a single reference catalogue. It is more likely that you will have to submit a couple of lines. If you are unlucky, you might have to submit many lines (if you switch between telescopes or reference catalogues frequently, even during one night).

  • XXX is your observatory code
  • The first YYYY MM DD.dddddd is an inclusive date after which this OSI line refers
  • The second YYYY MM DD.dddddd is an inclusive date before which this OSI line refers
  • P is the program code (generally only for professional sites, see this list)
  • M is the mode of observation (only given for observations made before 1992 Jan. 1, = “C” CCD, = “E” encoder)
  • RRRR is the catalogue code
  • T is the telescope code
  • OBJ is a comma-separated list of objects (designations in packed format) to which this OSI line refers

As another example, consider the same object being observed on the same night at the same observatory using different instruments. Let’s use the previous example with the complication that a single observation of K10A00A on 2010 Aug. 08.39394 was made with telescope 2 two hours after the last observation of the same object with telescope 1. Now we need four OSI lines:

If you frequently switch between different reference catalogues, you can simplify the OSI line by omitting the catalogue code for observations made after August 2001. Then you need distinguish only between different telescopes.

You should send your OSI line(s) to with the subject line “OSI”.

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