Re: Two unidentified obs

Leo Barhorst (
Thu, 08 May 1997 16:31:26 +0200 wrote:
> =

> On April 26th, around 21:12 UTC I observed a violently flashing satellite=

> (period about 1-1.5s, maybe 2 magnitudes brightness difference) while
> waiting for JERS. Analysis of the track led me to conclude that it might
> have been USSPACECOM 6677 (73037 C). Several days later, I observed it
> again (under adverse conditions) and was not clearly able to confirm the
> flashing. Observing position was 54.456N, 9.622E, 25m ASL. My questions:
> Can anyone confirm the flashing? Depends the visibility of flashes on  th=
> angle sun-satellite-observer?

Hello Marco,

I've run the predictionprogram Sat of the Belgian Working Group for your lo=
cation and =

the above time with these two satellites. Only JERS (92- 7 A, 21867) showed=
 up as =

visible at that time. 73- 37 C was visible at your location about exactly a=
 HOUR later, =

so I presume you've fallen in the summertime trap (as has happen to me seve=
ral times).
But running Skymap with the Alldat.tle file gives an other candidate: 90- 8=
1 BM, a piece =

of the break-up of the Chinese Feng-Yung 1-2 rocket. But this is not likely=
, as all the =

observed fragments (see the PPAS files) are magnitude 5 to 8. BM has not be=
en observed =

(at least not reported to PPAS). It is always possible that a fragment star=
ts flashing =

brightly as has happend with 92- 93 BL, 75- 52 M, 70- 25 CD.
The rapid flash pattern also strongly suggest it can be one of these kind o=
f fragments.

A little bit farther to the east was a passage of 93- 61 G, Eyesat minisate=
llite, a box =

0.23x0.23x0.24; so very unlikely you saw this. =

Can you give more details about the track you've observed this sat?

Did you observe the same rapid flasher several days later? Was this based o=
n predictions =

of 73-37 C?
The brightness of a satellite is very much dependent on its phase-angle. Ju=
st comare it =

with the moon: the new moon is not (or hardly) visible as the full moon is =
clearly =

visible. The same goes for sats. You can even see it when a steady sat trav=
elles across =

the sky and the brightness slowly changes as the phase-angle changes.

I'll inclue both satellites in my preditions and (weather permitting) will =
try to =

confirm your obs.


> This evening, May 7, around 20:52 UTC, while waiting for Cosmos 2313, my
> attention was drawn to an easily visible satellite (around magnitude 1.6
> at RA 16h31m, Decl 22=B012') that seems to be USSPACECOM 24670 (96069 A).=

> Using the formula given in QUICKSAT.DOC that evaluates to a standard
> magnitude of about 2m, so this might be an easy to catch satellite. I'd
> like to get a confirmation on this observation, too. Observing position
> was 54.317N, 10.133E, 30m ASL.
> =

> Greetings, Marco

This was indeed 96-69 A. Below are prediction for your position and the las=
t position is =

close to where you saw it.
96- 69 A        20h49m31s  13h07  - 5  30=F8     20h50m02s  14h00  + 4  37=F8=

    431 km      20h50m32s  15h07  +14  40=F8     20h51m02s  16h21  +22  37=F8=

The figure in each position is the elevation (height above hirozon).

As I was reading this mail again, before posting it, I suddenly realized th=
at the =

flasher you saw on 97-04-26 must have been at the track of 73- 37 C, but a =
hour earlier.
Otherwise you could not have identified it as 73- 37 C, although a wrong ID=
73- 37 C was at a different part of the sky than JERS, so I've run Skymap a=
gain for the =

right time and right part of the sky.

I had to wait almost to the end of the run and there it was: 96- 51 B (2429=
It is quite a bit to the north of the track of 73-37 C one hour later, but =
parallel to =

it. But as you picked it up (with the naked eye I presume) as you waited fo=
r JERS I'm =

quite sure it was 96- 51 B. I also often wait for 96- 51 B to appear just s=
itting in my =

garden chair and looking at the right part of the sky without binos.
Another candidate could have been 74-105 A (07593) whose track matches that=
 of 73- 37 C =

more closely. But this sat is smaller and not reported to PPAS. Its rocket =
is in PPAS, =

but not brighter than mag 4 and always steady.

General remark (to all):
>From the above it's clear that when reporting an UNID (unidentified sat) gi=
ving as much =

as possible information on the obs is crucial. Positions or which stars it =
passed and at =

least one (more or less) accurate timing is about the minimum for quickly i=
dentifying an =


-- =

Greetings and clear skies

Leo Barhorst		Alkmaar			The Netherlands
52.65 North		4.767 East		1 m ASL
Member of Seesat-L
Every day I wonder about the things I see in the (night)sky