Leo's April 1 obs + the chase is on.

Bjoern Gimle (b_gimle@algonet.se)
Tue, 2 Apr 1996 23:41:48 +0200 (MET DST)

>This evening I made the following observations:
....
>95- 72 B 96-04-01 20:14      LB                       almost S, mag 4
>....
> 95 72 B was accompagnied by a fainter satellite just 5 degrees above it
> and moving along with it at the same speed. I'm not sure of this
> magniude 6 object in fact is 95 72 B?
>
It probably wasn't.

This indeed seems like a rare occasion. Running SkyMap with Allen
Thomsons el960324, I find four objects moving in parallell, with
almost same speed, within a minute ( #20436, #20978, #21574 and #23752 )

The perfect pair is #21574 (91-50 A) ERS-1 with MM=14.32
and #20436 (90- 5 A) Spot 2, with MM=14.20.

On your observation Apr.1, their along-track separation was
about 1 second, which increased to about 11 minutes on Apr 2.,
so they will pass each other almost weekly, but such a close
pass is very rare. The smallest physical distance was 49 km at 20:17 UT

On the other hand, MM of DMSP is only 0.004 higher than of ERS-1.
DMSP will catch up on ERS-1 on the morning of Apr.4, within 30 km,
and it will be 8 months until they meet again.

#23752 ( 95-72 B) Skipper was 29 seconds after (and above) the pair,
(physical separation from ERS-1 35 km at 18:43 UT) and #20978 
(90-105 A) DMSP B5D2-5 another 45 seconds later and 5 degrees higher,
moving slightly faster.

On Apr.2 #21667 (91-59 B) Cosmos 2154 Rk will also follow 
#21088 (91- 6 B) Informator 1 Rk, along the same tracks, 
within 45 seconds. (Closest separation 13 km at 15:01:28 UT.)

Tomorrow, this will have increased to 134 seconds, so it will be
about 2 months until the next occasion ( see seesat-l/1918 )



Leo Barhorst will receive this with a SkyMap chart appended. 
In case the encoding is unusable, or someone else is interested,
I will also post it on my WEB :  http://www.algonet.se/~b_gimle 
(  http://www.algonet.se/~b_gimle/barhorst.htm )

I sent this (except for the last 7 lines) to seesat-l this morning,
but it has not appeared on the .ox. site before 15:30 UT !



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