message from Jeff Medkeff about his observation

Mike McCants (
Sat, 7 Mar 1998 16:39:37 -0600 (CST)

I received the following reply from Jeff Medkeff and a request
that I post his reply to the list.  The bottom line is that
his position and statement that the object did not move
very far in 10 minutes are not accurate enough to rule
out ETS-6 as a likely candidate.

I also received the following message from Russell Eberst:

>One point to add; 94-56A makes 1.67 revs/day, so that after 3 days,
>5 revolutions are completed, and circumstances virtually repeat themselves.
>Since the observations were made on March 4, there should be similar
>passes on March 7, 10, etc.

Mike McCants

**** Message from Jeff Medkeff:

Some further thought has convinced me that it is probably not a geosynch; I
am leaning toward Bill Gray's hypothesis right now - but I have not had a
chance to re-observe it, or check the various candidates provided by s.a.a.
posters and e-mail correspondents.

Would you mind forwarding the following comments back to seesat-L? I do not
subscribe there, as I get way too much mail already, but since the
discussion has 'spilled over', I think some of this should get aired over
there before too many wild geese die of exhaustion. I would appreciate it
if you would post it.

>Ron Lee wrote:
>>This came off of sci. astro. amateur (another reason to have 
>>the visual newsgroup).  

I voted "for", FWIW.

>31.51 110.26 Arizona  Epoch 1998
>  ***  98 Mar  4   Wed morning  *** Times are UT ***
>23944 CZ-3 Rk        96 39B    14 M 2.5 ELDY  1 M2   55
> 10.8  20266  36 161   10  40   15 11.5 -20.6  21696
> 10.8  19962  36 162   10  45   15 14.2 -20.4  21371
> 10.8  19648  37 162   10  50   15 17.0 -20.1  21035
> 10.7  19323  37 163   10  55   15 19.9 -19.9  20689
>Jeff Medkeff's observation:
>>Time: 3:52am March 4 MST (10:52 March 4 UT)
>>Position of the satellite J1998:
>>15h 12m -19d 47m
>The time of passage near Iota Librae for 96 39B would have been
>about 10:40:30 and it would have been over 1/2 degree south
>of that star.  The motion is 1 degree west in 10 minutes
>and that also does not match.

My observation - much as I hate to say this to a community being so
respectful of it - should be taken with a grain of salt, especially the
position and PA and rate of drift. I am not an avid satellite observer, but
I am an experienced astronomical observer. Normally I would be quite
confident of the observation, but there are some special circumstances
relating to this observation that mitigate against it being a terribly good

The first and most important is that on the night of the observation I was
conducting mundane observations of some deep-sky objects in support of a
column I am writing. As a consequence of the casual nature of the
observations, my equipment was not polar aligned well. Further, the
telescope I used - the only optical aid available at the time - is a very
new one, that I am not familiar with and still not terribly confident in
using at this time. Subsequent use of this telescope revealed that the Dec
circle was holding a residual of over 1.3 degrees (biased to the indicated
position being north of the real position) when the telescope was hanging
on the same side of the pier as at the time of observation. This residual
is not correctable, however, since the polar alignment when the residual
was measured was good, and on the night of observation, it was bad, but I
cannot quantify how bad. (Could have been as bad as 20 or more degrees from
properly aligned.)

The time of observation is also a little problematic. I did not have WWV
running, or even handy, as I normally do when observing, and I was not
wearing a watch. I determined the time as close as I could by belatedly
running a tape recorder, announcing into it the estimated delay between the
astrometric snapshot and the beginning of taping, and keeping the recorder
on until I got myself to a reasonably accurate clock. Then, using the time
the tape had been running, I corrected to derive the given time.

The upshot is that the time is probably only good to +/- 1.5 minutes, and
the position given is even worse; though the position is given to the
accuracy the telescope mounting mechanism reasonably allowed, the real-life
residuals here could be a couple degrees. The s.a.a. community is, by and
large, reasonably familiar with the fact of my new equipment and, I
assumed, would realize that the posted observation could be rather
imprecise; that is not necessarily the case here, however - so fair warning.

Trying to find something that *exactly* fits the profile of the observation
is probably not going to be productive. If someone finds something that is
a loose match, then it is probably as good a candidate as a close match.

There is one aspect of the observation as posted to sci.astro.amateur that
I am very much confident about, and that is the flashing behavior and
direction of drift. In light of all the recent identifications of Iridium
glints made by approximate magnitude and azimuth direction alone, I
probably got a little to confident that the satellite could be identified
based primarily on its glinting character.

>So the passage of ETS-6 near Iota Librae would have been
>about 10:54UT, but it would have been over 2 degrees north
>of that star.  

It is entirely possible that I made a mis-identification of the star, too.
I had been observing up west of the zenith; I have not observed in the
'late spring/early summer' areas around Libra for a *very* long time - well
over a year, at any rate. There is foliage in the direction of Libra at the
time. Kappa and 42 Librae would be candidates if I screwed up my star
identification, I suppose. I consider this possibility to be fairly remote,
but not impossible, and therefore worth bringing up. Mainly, I hold it out
as possible because I was extremely tired at the time of observation. 

>Also it is moving about
>0.8 degree west in 10 minutes and that does not match Jeff's
>observation that it was almost stationary for 10 minutes.

At the end of a long night, while tired, while observing through a
telescope/eyepiece with a true FOV of 1.9 degrees, while the wind was
blowing.... This satellite would have stayed in my low-power field for the
whole time, I assume, and not required me to re-center. I'm pretty flexible

>>This whole [flash] morphology seems quite unusual to me.

>I believe that it matches some of the other geosynch flashers
>quite well.

Great! Means I am not as crazy as I had given myself credit for.... I am
not much of a satellite observer, though, so I am unused to this kind of
behavior. Most of the satellites I have seen have been in low orbits, with
pretty slow rotations, meaning they rise and fall in brightness more
gradually and evenly. I have seen very few glinting satellites; only this
one glinted that regularly and predictably. Also, the colors of the glints
were distinctive - I think I alluded to the color of the secondary glint as
blue in the s.a.a. posting, which I have not seen in any other satellite,
though it may indeed be common.

>But of course the mean motion, eccentricity, and inclination are
>all quite uncertain.  If it really is a geosynch, it might be within
>a few degrees of this elset for the next few days.

I am cloudy now, and probably will be until Saturday early morning. I
welcome hearing other reports though. If you want to cc: me, I would be
delighted. I am at .

I am prepared to repeat the observation - I have printed charts of the area
for plotting the observed track, am equipped this time with binoculars to
scan wide areas, I am keeping the WWV radio handy in my eyepiece and
accessory case, and will run the tape recorder during the whole
observation. I'm determined not to get caught with my pants down again....
Some seesat-L people have mailed me some predictions. Ron Lee sent
predictions for probable clear periods for #23944, Taisto P. Lammi
forwarded a list of candidate objects that I can follow up on, and I am
prepared to run some predictions for Bill Gray's candidate 94056A. All I
lack is the weather. 

Jeff Medkeff          | Acting Assistant Coordinator
Rockland Observatory  | Association of Lunar and Planetary
Sierra Vista, Arizona | Observers, Solar Section

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