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irregular flares in Iridium-like path



 
 
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  #1  
Old August 23rd 04, 03:06 PM
William C. Keel
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Default irregular flares in Iridium-like path

On the evening of August 21 (2047 CDT, which would be 0147 UT on
the 22nd), I noted three bright, slow, and irregular flares from
an object moving northward across Ursa Major (the path went
about halfway between Eta UMa and Alpha CVn, and would have gone
almost in front of Epsilon UMa after it disappeared). The flares
were magnitude -2 to -3, and lasted many seconds at roughly the
same brightness. The location and path would be appropriate for
anorbit like Iridium 90 (and itc coplanar ilk), but this one
was moving northward rather than the southward motion that
those Iridia would have. This doesn't fit any of the non-operational
Iridium listings on heavens-above either. I was observing from close to
87.54W 33.21N.

Any ID hints will be appreciated!

Bill Keel
  #2  
Old August 23rd 04, 10:30 PM
Ted Molczan
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"William C. Keel" wrote in message
...
On the evening of August 21 (2047 CDT, which would be 0147 UT on
the 22nd), I noted three bright, slow, and irregular flares from
an object moving northward across Ursa Major (the path went
about halfway between Eta UMa and Alpha CVn, and would have gone
almost in front of Epsilon UMa after it disappeared). The flares
were magnitude -2 to -3, and lasted many seconds at roughly the
same brightness. The location and path would be appropriate for
anorbit like Iridium 90 (and itc coplanar ilk), but this one
was moving northward rather than the southward motion that
those Iridia would have. This doesn't fit any of the non-operational
Iridium listings on heavens-above either. I was observing from close to
87.54W 33.21N.

Any ID hints will be appreciated!


I searched for objects that passed within 5 deg of the mid-point between Eta
UMa and Alpha CVnRA (RA 13:20, Dec 44 deg), within 3 min of your reported
time.

The two best candidates a

Cosmos 928 r
1 10142U 77064B 04230.63950465 -.00000019 00000-0 -33608-4 0 7825
2 10142 82.9629 259.0681 0040368 277.0822 82.5746 13.78285756362438

Cosmos 1818
1 17369U 87011A 04233.52743078 -.00000024 00000-0 28856-4 0 3973
2 17369 65.0101 243.6756 0017233 282.0490 77.8649 14.31105546968335

Based on its path, 77064B appears to be the best candidate. It passed 0.2
deg above Epsilon UMa; Cosmos 1818 passed 1.9 deg below. Also, its
inclination is closer to that of an Iridium, consistent with your remarks on
direction of travel.

I am not aware of any history of reported flares by either object. 87011A
rotates slowly, resulting in a photometric period of the order of 10 s.

Ted Molczan


  #3  
Old August 23rd 04, 11:01 PM
William C. Keel
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Posts: n/a
Default

Ted Molczan wrote:
"William C. Keel" wrote in message
...
On the evening of August 21 (2047 CDT, which would be 0147 UT on
the 22nd), I noted three bright, slow, and irregular flares from
an object moving northward across Ursa Major (the path went
about halfway between Eta UMa and Alpha CVn, and would have gone
almost in front of Epsilon UMa after it disappeared). The flares
were magnitude -2 to -3, and lasted many seconds at roughly the
same brightness. The location and path would be appropriate for
anorbit like Iridium 90 (and itc coplanar ilk), but this one
was moving northward rather than the southward motion that
those Iridia would have. This doesn't fit any of the non-operational
Iridium listings on heavens-above either. I was observing from close to
87.54W 33.21N.

Any ID hints will be appreciated!


I searched for objects that passed within 5 deg of the mid-point between Eta
UMa and Alpha CVnRA (RA 13:20, Dec 44 deg), within 3 min of your reported
time.


The two best candidates a


Cosmos 928 r
1 10142U 77064B 04230.63950465 -.00000019 00000-0 -33608-4 0 7825
2 10142 82.9629 259.0681 0040368 277.0822 82.5746 13.78285756362438


Cosmos 1818
1 17369U 87011A 04233.52743078 -.00000024 00000-0 28856-4 0 3973
2 17369 65.0101 243.6756 0017233 282.0490 77.8649 14.31105546968335


Based on its path, 77064B appears to be the best candidate. It passed 0.2
deg above Epsilon UMa; Cosmos 1818 passed 1.9 deg below. Also, its
inclination is closer to that of an Iridium, consistent with your remarks on
direction of travel.


I am not aware of any history of reported flares by either object. 87011A
rotates slowly, resulting in a photometric period of the order of 10 s.


Ted Molczan



Thanks for the hint! The path of the Cosmos 928 booster is an excellent
match for the sketch I did at the time, and it's quite conceivable for
my watch to have been 2 minutes off. This was one of the most spectacular
"random" reflections I can recall (from an object that I wasn't
looking for).

Bill Keel
 




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