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Mike G's great answer clued me in on how to find the collection of astrometric observations of spacecraft which is maintained by the Minor Planet Center.

I've noticed that there are nonstandard format lines embedded within the observations. I can read the Date, RA, Dec, magnitude and band for the standard lines, but for the nonstandard lines with the 300 in columns 56-65 (marked xxx) I don't understand what this means and so far I haven't found a key that explains it.

I can just ignore them, but I'd really rather know what they are in case they are useful! or important.

From here: https://www.minorplanetcenter.net/iau/DASO/Obs/DASO_000559_Obs.txt

00000000011111111112222222222333333333344444444445555555555666666666677777777778
12345678901234567890123456789012345678901234567890123456789012345678901234567890
               DateDateDateDateRARARARARARADecDecDecDecxxxxxxxxxxmm.mmb
2015-005B    tC2017 09 22.18235 01 55 07.45 +12 36 17.4          13.7 RqD0559Y00
2015-005B    tC2017 09 22.18335 01 55 20.26 +12 34 01.7          13.8 RqD0559Y00
2016-038C    tC2017 09 22.16232 01 16 49.19 +13 00 29.0          11.9 RqD0559Y00
2016-038C    tC2017 09 22.16336 01 17 04.66 +12 58 35.4          11.9 RqD0559Y00
2016-038C    tC2017 09 22.16433 01 17 19.05 +12 56 49.9          11.7 RqD0559Y00
2016-055A     V2017 09 21.35632 00 24 08.35 -01 15 45.6          17.0 VqD0559247
2016-055A     v2017 09 21.35632 1 008.0567   +50.9060     300           D0559247
2016-055A     V2017 09 21.35702 00 24 08.04 -01 16 01.2          17.1 VqD0559247
2016-055A     v2017 09 21.35702 1 008.0567   +50.9060     300           D0559247
2016-055A     V2017 09 21.48556 00 23 00.22 -02 01 37.3          16.9 VqD0559247
2016-055A     v2017 09 21.48556 1 008.0567   +50.9060     300           D0559247
2016-055A     V2017 09 21.48625 00 22 59.83 -02 01 53.0          17.4 VqD0559247
2016-055A     v2017 09 21.48625 1 008.0567   +50.9060     300           D0559247
2016-055A     V2017 09 21.48660 00 22 59.53 -02 02 02.0          17.0 VqD0559247
2016-055A     v2017 09 21.48660 1 008.0567   +50.9060     300           D0559247
2016-055A     C2017 09 21.88530 00 23 55.81 -01 22 12.6          17.1 VqD0559595
2016-055A     C2017 09 21.88701 00 23 54.89 -01 22 45.3          16.6 VqD0559595
2016-055A     C2017 09 21.88872 00 23 53.96 -01 23 18.6          16.9 VqD0559595

See also: https://www.minorplanetcenter.net/iau/DASO/Obs/DASO_000562_Obs.txt

and also: https://www.minorplanetcenter.net/iau/DASO/Obs/DASO_000564_Obs.txt

uhoh
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  • Why the rollback of my edit? Those lines are exactly 80 characters long, and you have an obi-wan error (off by one) in your labels. For example, you have column 10 as 00 rather than 10. – David Hammen Feb 27 '18 at 09:40
  • @DavidHammen I started to rollback then realized a) it's you which means that b) it must have been helpful. Then tried to un-rollback then just got confused by the interface. Please fix it again, thanks! – uhoh Feb 27 '18 at 09:42
  • I saw the "red flag" which I thought to indicate a comment on another tab. I clicked it and it took me directly to the review view, which showed a ton of red which appeared to be deletion of the two lines (which it wasn't). Seeing a bunch of what looked like red deletion, I instinctively reversed it. I blame everything on the SE interface ;-) – uhoh Feb 27 '18 at 09:46
  • @DavidHammen I saw the red but missed the name (and the annotation) https://i.stack.imgur.com/AJX8w.png – uhoh Feb 27 '18 at 09:49
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    A better comment than "Corrected first two rows of ASCII data" by me would have been helpful. Then again, "Corrected Obi Wan error in first two rows of ASCII data" wouldn't have been very helpful at all. – David Hammen Feb 27 '18 at 09:51

1 Answers1

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Those are data from "roving observers", essentially any ground-based observation that isn't from an observatory blessed with a three character observatory code. The observatory code is columns 78 to 80 of the entries. Note that the observatory code for those roving observer entries is always 247".

The longitude, latitude, and elevation of the known observatories are known. This isn't the case with those "roving observers", which is why they take two lines. The first line of a "roving observer" entry contains a "V" in column 15 and "247" as the observatory code. The second line of a "roving observer" entry contains a "v" in column 15. The bulk of the second line contains the longitude, latitude, and altitude of the observer.

David Hammen
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  • Okay! That explains why the lon/lat appears to be somebody's back yard! I tried the theory that it was a coordinate, but when I saw no observatory, thought it was not right. The first try was in the ocean, before I'd reversed lat/lon to lon/lat. – uhoh Feb 27 '18 at 09:50
  • This reminds me of when I got some very strange numbers trying to get the Juno spacecraft's orbit relative to "Jupiter". In this case Jupiter is a telescope in somebody's front yard in Jupiter, Florida! https://i.stack.imgur.com/6EAqO.png $\rightarrow$ https://i.stack.imgur.com/uBkbg.png – uhoh Feb 27 '18 at 10:08