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General Astronomy >> General Observing and Astronomy

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Daniel Guzas
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Reged: 11/20/10

Loc: Bethlehem NH/ Boston MA
Detail on Stationary satelites?
      #5678582 - 02/13/13 11:29 PM

Ok I had a thought while watching a program on PBS tonight.

Is it possible to see detail on a Geosyncranous satellite at high magnification? Since it should be fixed in the sky that would make tracking it easy right? I figured since it would not be moving very much it would make a good target to see if any detail could be seen.

Anyone tried this?

Just wondering....


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GlennLeDrew
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Re: Detail on Stationary satelites? new [Re: Daniel Guzas]
      #5678616 - 02/13/13 11:48 PM

You could calculate the size of satellite required to subtend a minimal width of, say 2 arcseconds (0.00056 degree) when at its distance of 22,000 miles.

TAN(0.00056) * 22,000 = 0.21 miles.

Pretty big!

See how easy it is to investigate (and answer your own) interesting questions?

Back in grade 9, when I was first introduced to trigonometry, I felt like I was given a key to the secrets of the Universe. The power to solve problems involving size, distance and angle was exciting. I immediately recognized the utility of this potent yet simple 'wizardry', and have used it continually ever since.

I only hope my enthusiasm for problem solving, and playing with numbers as a way to understand how things work, inspires others. If I come across as smug, that's not my intention at all.

Edited by GlennLeDrew (02/14/13 02:15 PM)


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careysub
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Loc: Rancho Cucamonga, CA
Re: Detail on Stationary satelites? new [Re: GlennLeDrew]
      #5678647 - 02/14/13 12:26 AM

Nonetheless, looking at geosynch satellites might be an interesting diversion:
http://www.satobs.org/geosats.html

You could have a (generally very dim) star for star testing that does not move in the sky:
"Typically the satellite will be in the mag. +11 to +14 range (or dimmer), but brightening by several magnitudes when the geometry is favourable (around mag. +5 to +6 is not untypical). One satellite is reported to have briefly been visible to the naked eye at mag. +3!"


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obin robinson
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Re: Detail on Stationary satelites? new [Re: Daniel Guzas]
      #5679043 - 02/14/13 09:46 AM

The vast majority of my observing at night is of satellites. You cannot see any detail on the geostationary ones. You can see detail on only the low earth orbit ones. The "detail" is basically the solar array or antenna. It is still well worth it to me. Satellites are more fun than anything else!

obin


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Daniel Guzas
professor emeritus
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Reged: 11/20/10

Loc: Bethlehem NH/ Boston MA
Re: Detail on Stationary satelites? new [Re: obin robinson]
      #5680406 - 02/14/13 11:23 PM

Thanks for the replies! I have to brush up on my trigonometry as it WILL help me unlock some of these intriguing questions.

Also Orbin, How would you go trying to track a normal satellite? They move so fast?

I assume you have to be really good at manual tacking or do you have a mount which can tack that fast?


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obin robinson
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Re: Detail on Stationary satelites? new [Re: Daniel Guzas]
      #5680818 - 02/15/13 08:18 AM

I use the heavens-above.com website to tell me what is going to be overhead that night or morning. It is essential that you put your latitude and longitude into the location info as accurately as possible. Use a GPS or map software to get your info. I then look through the menus to see what is going over at what time and I print the sky charts out for each satellite pass.

Last night I saw 4 very bright satellites. The brightest one was the same magnitude as Jupiter. I also spotted one imaging spy satellite. You can identify those only later on because they won't show up on any software or published charts.

The Meade goto mount will track everything except really fast movers on a Molniya orbit. When those satellites swing by on their perigee they can cross the sky in literally a minute! They are moving much much faster than the fastest airliner you have seen at night. For those satellites I use binoculars.

The most detail I have ever seen is an antenna or solar array. When they reflect the sunlight just right the satellite looks like a silver soup can with a rectangle attached to it. Rocket bodies which are tumbling in space will strobe from dim to bright and back again. I am getting a goto for our 10" newtonian so that way I can try and get photos of these satellites in orbit. The meade 497 autostar hand controller will allow you to download satellite passes. I have several hundred of the brightest ones and some geostationary ones programmed in.

obin


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Daniel Guzas
professor emeritus
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Reged: 11/20/10

Loc: Bethlehem NH/ Boston MA
Re: Detail on Stationary satelites? new [Re: obin robinson]
      #5681216 - 02/15/13 11:27 AM

Most excellent Orbin! Thanks for the reply. I will take a closer look at trying to bag some satellites.

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Dave Mitsky
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Re: Detail on Stationary satelites? new [Re: Daniel Guzas]
      #5681842 - 02/15/13 03:56 PM

I've observed some geostationary satellites through a 20" classical Cassegrain. No detail was visible, of course, but it was nevertheless an interesting sight to see.

Dave Mitsky


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obin robinson
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Reged: 10/25/12

Loc: League City, TX
Re: Detail on Stationary satelites? new [Re: Dave Mitsky]
      #5682012 - 02/15/13 05:25 PM

I forgot to add that you can find all the geostationary satellites using Stellarium. Go through the menus to and you can have it display all of them. All you have to do after that is keep your telescope still and watch the "star" that isn't moving. They are very difficult to see unless you have a pretty big scope, a really dark sky, or the perfect conditions where their solar array is going to be reflecting the sun rot at you.

The iridium satellites are another easy one to spot. They will get several times brighter than Jupiter. They can even be seen after sunrise!

obin


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GlennLeDrew
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Re: Detail on Stationary satelites? new [Re: obin robinson]
      #5682049 - 02/15/13 05:44 PM

To put Iridium flashes into perspective, compared to Jupiter and Venus, the latter of which have peak brightnesses of -2.5 and -4.4 magnitude, respectively. A -8 magnitude Iridium flash is 28 times brighter than Venus and 250 times brighter than Jupiter.

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derangedhermit
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Reged: 10/07/09

Loc: USA
Re: Detail on Stationary satelites? new [Re: GlennLeDrew]
      #5682503 - 02/15/13 10:36 PM

I guess the ISS is the artificial object that consistently shows the most detail when in a favorable position for viewing from a specific location on earth.

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Lee Jay
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Re: Detail on Stationary satelites? new [Re: derangedhermit]
      #5682538 - 02/15/13 11:01 PM

Quote:

I guess the ISS is the artificial object that consistently shows the most detail when in a favorable position for viewing from a specific location on earth.




It has a nice combination of enormous size, relative closeness, and mountains of detail.


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obin robinson
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Reged: 10/25/12

Loc: League City, TX
Re: Detail on Stationary satelites? new [Re: Lee Jay]
      #5682901 - 02/16/13 07:35 AM

True about the ISS. Under the right conditions you can see the solar arrays even with low power binocular. If you are lucky you may even see it and the Soyuz module that is attempting to dock with it.

obin


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azure1961p
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Re: Detail on Stationary satelites? new [Re: obin robinson]
      #5684878 - 02/17/13 10:11 AM

I caught the ISS by accident one evening sitting behind my condo with binos. This Jupiter brightness thing comes climbing directly overhead - no flashing port and starboard lights just this steady bright fast moving white light. Binos made it enigmatically odd - my 8x42s were showing something g larger than a point source but without out clear edge distinction. An old observing buddy in another town was simultaneous imaging it and confirmed it as the ISS. I wish to heck I had my Ranger out that evening - 35x and the panels would've been had nicely.

I've never tried for a geostationary at high power though I've seen them at star parties.
Pete

Edited by azure1961p (02/17/13 10:13 AM)


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Achernar
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Re: Detail on Stationary satelites? new [Re: Daniel Guzas]
      #5685031 - 02/17/13 11:43 AM

I'm afraid not, they are too far away for that. Even through geotstationary communications satellites can weigh as much as and be as large as an RV, they are points of light in a telescope when they are 22,300 miles up. I've seen a few of them, they will stay still in the eyepiece while the background stars and other objects drift across the field of view. I have however seen the solar panels and modules of the ISS with a 6-inch telescope.

Taras


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