Re: Unknown 95058B and viewing accessories?

Bjoern Gimle (b_gimle@algonet.se)
Sat, 8 Mar 1997 16:22:27 +0100

Bill Blair (wblair@rmi.net) wrote:
....>
>Months ago, while out looking at nebulas with my binocs, I saw  a 
>very rapidly flashing satellite which was visible with the naked eye.  
>The flashes were very pronounced and gave the impression of a rapidly 
>spinning "disco ball" in orbit.  Do the laser ranging satellites with 
>retro-reflectors have such characteristics?  Is there anything else that 
>might produce such rapid and sharp flashes?  Unfortunately, I didn't 
>record any data on the pass, so I couldn't determine what satellite I saw by 
>using tracking software when I got home.
>
I'm no expert at these sats, but I've seen no other answer.
There are some nice flashing laser reflectors, like #16908 EGP.
Several classified USA satellites, some of which move into elliptical,
even Molniya type orbits - and lost by the amateurs - have sub-second
flashing. USA-40 ? USA-36 ? 
Most Zenith rockets, like #23705 that you saw, have 0.4 seconds or shorter
flash period soon after launch.
 
>....  Any 
>suggestions on additional stuff to help out with such things as magnitude 
>estimates or exact tracking of the path of a satellite to allow my (eventual) 
>contribution to the tracking of unknown and classified objects?  Please give 
>me all of your clever ideas.  They'll really be welcome.
>
I use a pair of light-weight (104 g) Beecher Mirage binoculars, worn like
a pair of glasses, when I have to search for a satellite more than 2-3
minutes, and to operate the stopwatch more accurately.

If you want/need to observe more than two-three positions before making
notes, or you are uncertain of the identification of your reference stars,
a tape recorder is handy.

But you don't need more equipment to be a useful contributor.

For an object with large drag, like low-perigee transfer rockets and objects
near decay, even a note "5-6 min early on YYMMDD at HHMM UTC using elset #NNNN"
(or include a copy of the elset) will help others find it or improve the elset.
Any well-known satellite orbit, even after a small orbit maneuvre, can be
improved by a single second-accuracy time observation.
To identify an unknown among available elsets, a single position with
10-30 seconds and 1-5 degrees accuracy usually suffices, depending on
brightness. 
To verify position/timing accuracy, two or more positions are recommended.
To determine an orbit completely, we need three or more acurate time/positions.

The easiest way to determine positions is to find a (close) pair of stars,
that you can identify later, on either side of the track. Note the time
and fraction/percentage of the connecting line when the satellite track
"cuts" it. (Crossing the extension of the line is OK, but less accurate)
With a graphic program like SkyMap, you can accurately re-create your
field-of-view and move the cross-hairs to the position and read out the
coordinates. If your conversion of visual position to numbers is not so good,
you will probably remove most of that error by recreating it graphically.

You can also estimate magnitudes by finding a star slightly brighter, and 
one fainter, within your field-of-view. When you put SkyMap's crosshairs
on the stars and press ? or q, it gives its magnitude (+catalogue # and
position).
Comparisons are more accurate if you can observe slightly out-of-focus.

If the satellite orbit is known, you can confirm the identification of star
pairs by checking the time tags/ticks along SkyMap's prediction with your
stopwatch timings ( and find the approximate prediction errors )


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