ASTRO: Three Geostationary Satellites in 9 seconds

Yet another "find" when cleaning the hard drive. This one from only a
few months ago. I was trying for an Arp galaxy at -7 degrees
declination but clouds moved in before I got any data. I'd accidentally
left the "auto save" turned on so my focus frames were captured. They
were 9 seconds and already dimmed by the clouds moving in. I never did
image the galaxy as by the time the weather cleared the moon was in the
way then it was too far west. So it will have to wait until next year.

I was about to purge the focus frames I'd accidentally saved when I saw
one had three streaks. Each horizontal and the same length. Then I
realized this was exactly the declination of the geostationary belt at
my latitude. Apparently three birds are stationed at the same position.
Only one can be working as the band width of a dish is wider than
their spacing of only a few minutes of arc. I checked and found that in
9 seconds they should trail 134" of arc at -7 degrees. Sure enough that
was the trail length. Direction right, length right and position right
so that has to be what these are. I may never image this galaxy however
as these birds are positioned every 2 degrees or so (closer and the
beams would overlap). That would be one bird every 7.5 minutes. What a
mess that would create. Hopefully they'd be at slightly different
declinations as these were and if I used a lot of frames so I could use
a sigma combine that might do the trick.

In any case this will be a tough object from my declination it appears.

Here's the 9 second focus frame dimmed severely by clouds. Image
reduced to 2.5" per pixel

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

Rick,

that's a neat result from an otherwise lost night. I don't think I ever had
some of these in my images, although it probably is difficult to tell which
kind of satellite made a track as even these slow moving objects will cross
the whole frame in one of my 5 minute exposures.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Yet another "find" when cleaning the hard drive. This one from only a
few months ago. I was trying for an Arp galaxy at -7 degrees
declination but clouds moved in before I got any data. I'd accidentally
left the "auto save" turned on so my focus frames were captured. They
were 9 seconds and already dimmed by the clouds moving in. I never did
image the galaxy as by the time the weather cleared the moon was in the
way then it was too far west. So it will have to wait until next year.

I was about to purge the focus frames I'd accidentally saved when I saw
one had three streaks. Each horizontal and the same length. Then I
realized this was exactly the declination of the geostationary belt at
my latitude. Apparently three birds are stationed at the same position.
Only one can be working as the band width of a dish is wider than
their spacing of only a few minutes of arc. I checked and found that in
9 seconds they should trail 134" of arc at -7 degrees. Sure enough that
was the trail length. Direction right, length right and position right
so that has to be what these are. I may never image this galaxy however
as these birds are positioned every 2 degrees or so (closer and the
beams would overlap). That would be one bird every 7.5 minutes. What a
mess that would create. Hopefully they'd be at slightly different
declinations as these were and if I used a lot of frames so I could use
a sigma combine that might do the trick.

In any case this will be a tough object from my declination it appears.

Here's the 9 second focus frame dimmed severely by clouds. Image
reduced to 2.5" per pixel

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

They are easy to identify. You have to be pointed at the belt. -7.016
degrees for my latitude (-7.51 for 52.5N). The trails are exactly west
to east (unless your polar alignment is screwy) and are the length in
seconds of arc that equal the cosine of your declination x exposure in
seconds x 15 or 134" in my case. Since the cosine will be about .99 for
both of us you could use that. Difference was only 1" less than
equatorial rate at my latitude.

I took several 10 minute frames through the clouds hoping to get
something. Of course then they move through the entire frame. I had 2
or more in all but one frame that only had 1. Since they overlapped
even with a sigma combine (Deep Sky Stacker) I had a fuzzy belt of light
across the middle of the image. Impossible to process out. To take
this Arp I'll have to pre map the belt then plan 5 minute frames between
positions. A big pain. Its too far west now so that's a next year project.

I've since been sent this link to a WMV file of the activity at one
European geostationary position taken with a still C14 at f/3.3
http://jatobservatory.org/images/Ast...KR-Arrival.wmv
It shows a much bigger traffic jam than I encountered but one you might
as it would be only a bit west of your meridian. The movie appears
intentionally out of focus to make the last frame showing their motion
over the full night. I'd have focused it and just photoshopped the
trails making that clear in the picture label of course. There's
something about being out of focus that grates my brain like fingernails
on a blackboard. Still it is a fascinating movie. Though the out of
focus satellites all show an odd pie shaped notch taken out of one side.
I wonder what made that? I've not tried a 3.3 compressor so maybe
that had something to do with it. Must make for a funny spike when in
focus.

I was trying for Arp 140 at -7d 3', that's the faint fuzzy in the
center. About the same time I did Arp 146 (not processed) at -6d 38m
and never saw one so they stick very close to their calculated
declination. 146 is very small and seeing not really up to 0.5" per
pixel but I tried anyway. May not process it and just wait for a better
night next year. Depends on how desperate for objects to process I am.

Rick


Stefan Lilge wrote:

Rick,

that's a neat result from an otherwise lost night. I don't think I ever had
some of these in my images, although it probably is difficult to tell which
kind of satellite made a track as even these slow moving objects will cross
the whole frame in one of my 5 minute exposures.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...

Yet another "find" when cleaning the hard drive. This one from only a
few months ago. I was trying for an Arp galaxy at -7 degrees
declination but clouds moved in before I got any data. I'd accidentally
left the "auto save" turned on so my focus frames were captured. They
were 9 seconds and already dimmed by the clouds moving in. I never did
image the galaxy as by the time the weather cleared the moon was in the
way then it was too far west. So it will have to wait until next year.

I was about to purge the focus frames I'd accidentally saved when I saw
one had three streaks. Each horizontal and the same length. Then I
realized this was exactly the declination of the geostationary belt at
my latitude. Apparently three birds are stationed at the same position.
Only one can be working as the band width of a dish is wider than
their spacing of only a few minutes of arc. I checked and found that in
9 seconds they should trail 134" of arc at -7 degrees. Sure enough that
was the trail length. Direction right, length right and position right
so that has to be what these are. I may never image this galaxy however
as these birds are positioned every 2 degrees or so (closer and the
beams would overlap). That would be one bird every 7.5 minutes. What a
mess that would create. Hopefully they'd be at slightly different
declinations as these were and if I used a lot of frames so I could use
a sigma combine that might do the trick.

In any case this will be a tough object from my declination it appears.

Here's the 9 second focus frame dimmed severely by clouds. Image
reduced to 2.5" per pixel

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".





--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".