AFP-731 observations

[Allen Thomson]

Russell Eberst has kindly retrieved the observations
of AFP-731/1990-019B/NORAD-20516/USA 53 from the archive at
Greenwich and has given me permission to post them here. The
data are in a reporting format used by visual satellite observers
-- I've forgotten what some of the entries are, but have
indicated the parts which are germane to the discussion we've
been having. The time of observation, YYMMDDHHMM, is the
most interesting one and shows that the pattern of observations
was as had been understood earlier, except for two sightings on
the night of June 19. The satellite was next reported on
October 9, and then with increasing frequency until it
vanished sometime after the pass of November 5.

The overall pattern is very roughly consistent with the
visible passes which were deduced from the last available element
set -- visibility in March-April, very briefly in mid-summer (but
calculated to be mid-July rather than mid-June), then many passes
in September through October. There are, however, still important
unanswered questions, such as why there were no sightings from
March 4 through the end of April and, of course, what happened
after November 5.

It would be interesting to see how well the two sightings on
19 June fit the orbit determined in October -- I'll try to run
the simulation in the next day or two and report back.

With respect to the generic Nth country space surveillance
question, it's worth noting that all the AFP-731 observations
were made at only two sites, 2420 and 2563, which presumably
correspond to Edinburgh and somewhere in France. A
geographically dispersed, modestly coordinated network of
observers could take much better advantage of varying lighting
conditions and weather.

*******************************************************************************

90-19-BsiteYYMMDDHHMMSSss RA DEC
9001902242090030206181421 02 21032045 +495205 120 4 +05+05 0 S
9001902242090030406045468 02 21032044 +494305 120 4 +12+12 0 S
9001902242090030406052137 02 21021004 +435953 120 4 +16+16 0 S

9001902256390061923000285 1 12192001 +640788 1 4 +2
9001902256390061923004713 1 12220252 +642700 2 4

9001902242090100919081478 02 21222759 +305513 120 4 +25+25 0 S
9001902242090100919092655 02 21003824 +390934 120 4 +24+24 0 S
9001902256390101418392839 1 12071514 +751200 6 4
9001902256390101418395859 1 12061406 +684122 0 4 +15+25
9001902242090101619290752 02 21121100 +750830 120 4 +58+58 0 S
9001902242090101619300969 02 21065744 +705051 120 4 +50+50 0 S
9001902242090101619311192 02 21053855 +563229 120 4 +52+52 0 S
9001902242090102119010021 02 21061109 +600118 120 4 +62+62 0 S
9001902256390102218323825 1 12104807 +564050 0 4 +6
9001902256390102218323825 1 12104807 +564050 0 4 +6
9001902256390102218331473 1 12094733 +590300 0 4
9001902256390102218334740 1 12084917 +591770 0 4 +5
9001902256390102220174253 1 12105673 +590930 1 4 +7
9001902256390102220180093 1 12102455 +595400 0 4
9001902242090102318055477 02 21093823 +723122 120 4 +52+52 0 S
9001902242090102318061308 02 21081512 +723354 120 4 +50+50 0 S
9001902242090102318074976 02 21045044 +551124 120 4 +61+61 0 S
9001902256390102518571473 1 12095082 +575940 0 4 +6
9001902256390102518574882 1 12085356 +582592 1 4 +45
9001902242090102518580011 02 21061131 +591506 120 4 +47+47 0 S
9001902256390102618303506 1 12091429 +580816 2 4 +6
9001902256390102618310951 1 12081642 +575406 0 4 +4
9001902256390102620133347 1 12125364 +541920 1 4 +45
9001902256390110117334806 1 12085358 +582532 1 4
9001902256390110117342090 1 12075718 +590996 0 4
9001902256390110117351041 1 12063334 +565544 1 4
9001902256390110117351757 1 12062230 +561716 0 4
9001902256390110117353680 1 12055542 +541692 1 4
9001902242090110218501653 02 21115833 +692611 120 4 +52+52 0 S
9001902242090110218510956 02 21075701 +793712 120 4 +49+49 0 S
9001902242090110318230018 02 21115545 +614435 120 4 +51+51 0 S
9001902242090110318240368 02 21092240 +751927 120 4 +47+47 0 S
9001902256390110517303608 1 12094914 +594392 1 4
9001902256390110517314032 1 12074668 +641308 1 4
9001902256390110517320130 1 12065724 +634728 0 4

[Allen Thomson]

A correspondent has provided the full format for RGO one-line
satellite observation reports, the details of which I had disremembered:

************************************************************************

Layout for satellite observation reports submitted to the Royal Greenwich
Observatory[:]

Send inquiries, requests for site number assignments, etc. to:

S...@gxvf.rgo.ac.uk

Send observation reports to:

ARC...@gxvf.ro-greenwich.ac.uk

Here is the layout of an observation report:

column
1- 7 YYNNNCC (international designator)
CC = piece of launch: 01 = A, 02 = B, etc.
use 9900000 for unidentified sats

8-11 NNNN (Site Number assigned to your site by RGO)

12-27 YYMMDDHHMMSSssss (time of obs)

28-32 Nnnnn (estimated timing accuracy, seconds)

33 timing standard:
1 = UTC, 2 = speaking clock, 3 = BBC time pips

34 type of coordinates you are providing:

RA dec
1 = HHMMSSss DDMMSSs
2 = HHMMmmmm DDMMmmm
3 = HHMMmmmm DDddddd

az el
4 = DDDMMSSs DDMMSSs
5 = DDDMMmmm DDMMmmm
6 = DDDddddd DDddddd

35-42 Right Ascension or azimuth

43 sign of declination: + or - or blank

44-50 declination or elevation

51-54 estimated accuracy of obs:
SSSs if column 34 = 1 or 4
MMmm 2 or 5
Dddd 3 or 6

55 Epoch: 0=date of obs 1=1855 2=1875 3=1900 4=1950 5=2000

56-63 NNNNNnnn (slant range, kilometres)

64-68 NNnnn (estimated accuracy of slant range, kilometres)

69 sign of maximum magnitude: + or -

70-71 Nn (maximum magnitude)
If magnitude is 10 or dimmer, use column 69 for tens digit. A
+ sign will be assumed. E.g. +99 = mag 9.9, 100 = mag 10.0

72-74 minimum magnitude; same format as maximum magnitude

75-79 NNNnn (flash period, seconds)

80 S=steady I=irregular R=regular variations F=constant flash period
X= Irregular flash period E unusually faint because of eclipse

In the preceding description, lower case letters [are used] to indicate
digits to the right of an IMPLIED decimal point. The decimal point
itself is NEVER USED in an observation report. For example, the
format for observation time is:

YYMMDDHHMMSSssss
therefore,
93010302572015 = 1993 January 3, 2h 57m 20.15s.

Pad any non-significant place to the right of a decimal point with a
blank. Use a zero only if the zero is significant. For example, the
time in the above example was measured to only .01 second, so the two
remaining places were padded with blanks. If, instead, the fractional
seconds field contained 1500, it would imply that the time had been
measured to .0001 second.

Start a new line after the last significant character. For example, if
you observed only right ascension and declination, begin a new line after
column 55.