Satellites passing through lunar umbra

Matson, Robert (ROBERT.D.MATSON@cpmx.saic.com)
Wed, 17 Feb 1999 18:55:36 -0800

Hi Cees,

> I'm a member of the Solar Eclipse Mailinglist, and I recently posted
> the following question:

>>As we can all check the path of totality for the August Total Solar
>>Eclipse is going to occur at 09h31m UT at a Western longitude of 65
>> and a Northern latitude of 41. If you were on the same latitude
>> but on a longitude of 75 (Philadelphia, USA), and if you were
>> observing satellites, it could be possible that a satellite that
>> is illuminated by the Sun, would suddenly disappear because it is
>> being eclipsed by the Moon's shadow. After some seconds, minutes,
>> it would reappear again, because the shadow has left or it has
>> moved out of the shadow.

> Has someone ever observed such an event, or is it not observable because
> of some practical reason I can't think of?

It is observable, and predictable.  I added this capability to SkyMap a few
versions
ago (in time for the last total eclipse).  Looking forward to trying it out
again for
the August 11 eclipse (though I expect to be in Europe for the eclipse, so I
will
have to leave it to others to look for satellites passing through the lunar
umbra).

The east coast is definitely in prime position.  Anyone looking for
satellites
at around 5:20am EDT on 11 August is going to have an interesting time.
A *lot* of satellite magnitudes are going to be much dimmer than most
prediction programs will tell you.  I have already identified 11 satellites
that
are likely to experience at least 90% eclipse at some point that morning.
They are, in no particular order:  Iridium 12, Iridium 84, Cosmos 44 R/B,
Cosmos 426 R/B, Cosmos 371, Cosmos 921, Cosmos 970, Cosmos
1091 R/B, Cosmos 1535 R/B, Cosmos 2112 and Meteor 1-10 R/B.

I decided to check out some specific locations to see what they could
expect.  The following cities will see at least some if not all of these
satellites:  N.Y.C. metro area, Philadelphia, Pittsburgh, Baltimore,
Washington D.C. area, Richmond, Raleigh-Durham, Savannah,
Huntsville, and Gainesville, Fla.  Of course, the same applies to
any cities bounded by these cities.  --Rob