Satellite Observing Discussion

[Mee_n_Mac]

That doesn;t really look like the ISS, unless there were some clouds. It rarely fades from view in mid pass, generally stays pretty close to the same brightness except for the rare flare off the solar arrays.

MW

I can pretty much guarantee it was the ISS; it was too bright to be anything else and it was right on schedule and position per Heavens-Above. It "faded" only because there was varying cloud cover that night. Much to my consternation there was a band of clouds right in the path I had to take the pic. You can just make them out from among the sensor noise.

 

[MeteorWayne]

Cool, that makes sense then

 

[MeteorWayne]

Since this concerns a visible satellite, I have copied this information here.

http://www.space.com/spacewatch/x-37b-s ... 00823.html

"The U.S. Air Force's secretive X-37B space plane apparently boosted itself into a new orbit Aug. 9, according to reports from seasoned satellite trackers around the world, SPACE.com has learned.

The orbit-raising maneuver was first noticed Aug. 14 by amateur skywatcher Greg Roberts of Cape Town, South Africa, when the object failed to appear as predicted by the last known orbit. After several nights of searching, Roberts found it again on Aug. 19, which enabled the new orbit to be estimated with sufficient accuracy to easily locate the X-37B space plane on subsequent nights."

...........

From launch until Aug. 9, the X-37B was in a 40-degree orbit, zipping around the Earth at a 250-mile-by-260-mile (403 km by 420 km) orbit. It maintained a nearly constant altitude by making frequent small maneuvers to counter atmospheric drag, Molczan said.

Then on Aug. 9, the space plane made two larger maneuvers, increasing its mean altitude by roughly 17 miles (27.5 km).

The mystery space plane's first orbital adjustment occurred near its apogee (high point of orbit), raising its orbit to approximately 260 miles by 276 miles (420 km by 445 km). The final maneuver occurred near the next high point of its orbit, which happened to coincide near overhead passes of Vandenberg Air Force Base in California and Schriever Air Force Base in Colorado. The resulting orbit was 268 miles by 276 miles (432 km by 445 km), Molczan noted.

.........

Note the Heavens-Above satellite prediction page was updated on Aug 24 with an orbit: 428 x 444 km, 40.0° (Epoch Aug 24), so should be fairly accurate.

 

[MeteorWayne]

I was out plotting meteors this morning and saw 6 satellites (haven't transcribed my tape yet so haven't ID'd them).

Again, when I am meteor observing, that is my priority, so any sats I see are just those that wander through my field of view. If I'd been looking for sats, there were 38 (brighter than mag +4.5) listed on the Heavens-Above page during the 2:04 I was observing from 3:26 to 5:30 AM.

3 were normal sats that I should be able to ID, but 3 were not of steady brightness. One was faint (~ +4.3) but for 10 seconds flashed brighter very fast; probably 4-5 flashes per second!

Another, low on the eastern horizon only flashed bright (~ mag 0) 3 times. Real short flashes, < 0.5 seconds. It was invisible the rest of the time.

A third traveled from Auriga down through the Big Bear's from paws. It was invisible most of the time, but slowly flared 3 times for about 5 seconds, getting as bright as first magnitude.

Meteors and satellites were tied at 6 for the morning, a slow morning for meteors.

Oh, and a fantastic crescent moon (~ 6% illuminated) rising in the east as I came home...the earthshine was very brightly lighting up the shadowed part of the moon, so much so it was easy to pick out the "Man in the Moon" maria.

MW

 

[adrenalynn]

I'd be interested to learn whether it would be possible to receive transmission from a satellite using an antenna of some sort. Besides the TV and radio satellites, I mean. I know that the radio amateurs occasionally have contacted the ISS and perhaps Soyuz too.

More than occasionally. I've worked both the ISS and several STS. And of course, we amateurs have our own communications satellites up there too.

That said, and excluding those: Absolutely. You need to know the frequency of the beacon as well as how it's carried.

Here's my favorite source: http://www.zarya.info/Frequencies/FrequenciesAll.php

A helical or quad array in the appropriate band will be helpful. Of course, it should go without saying that you'll also need a receiver that is reasonably sensitive enough to receive the band you're trying to work.

Another point is to not get too hung-up on the exact frequency. You should be able to hear the carrier right around there, but due to Doppler, you'll need to be able to smoothly tune up and down small steps to make the beacon out.

Incidentally, that site has some curious beliefs about what some of the sats are for. They believe the OSCAR sats are all US Military. OSCAR is Orbital Satellite Carrying Amateur Radio, they're flown by AMSAT, and are by definition very easy to work...

 

[Esper_Ranger]

Twin satellites?

Hi, I'm a new member and not sure if this is the right sub-forum for this question. I'm also not very technically savvy so I won't be able to provide many details.

I live just to the southwest of Louisville, KY (40258 zip) and on the nights of Sept 3 and Sept 4 I was out with a regular pair of binoculars doing some stargazing and satellite watching. On both nights around 9:30 or later I noticed what looked like a pair of satellites following each other extremely closely. Through the binoculars I'd say that they would be less than a finger width apart (again, I'm not very knowledgeable on the tech jargon).

The first night it looked like they were a little further apart and moving south to north. The second night they were much closer and moving southeast to northwest. Of course I'm not even sure that they were the same objects on different nights. I am sure they were not an airplane(s) since they were too high and didn't have any blinking lights.

If anyone can give me an idea of what they are and an idea on when I can expect to see them again it would ease my curiosity tremendously. Thanks.

 

[MeteorWayne]

Re: Twin satellites?

This sounds like the NOSS satellites



NOSS from Wiki

There have been many good passes (sometimes 4 or 5 per night) recently; they typically are 5 or 6 seconds apart.

To get predictions, click on this, then bookmark it:

http://heavens-above.com/?Loc=Louisvill ... 128&TZ=EST

This is for the city center. You can use the "select from map" link near the top to refine your location. For most satellites, that makes little difference; the only one where it's important is the "Iridium Flares" section, where your location must be accurate within a mile or two since the bright spots from this satellite are very small.

For example, here's the satellite list for the night of Sept 4:

http://heavens-above.com/allsats.asp?la ... 9375&Mag=4

You can see at 21:48 to 22:01 (9:48 to 10:01 PM) the NOSS pair made a S-NE pass about 51 degrees in the ESE at maximum elevation. Have fun!

I am going to move this to the Ask the Astronomer forum. Welcome to Space.com!

After you've seen it there, I will merge it into the existing discussion about observing satellites.

Wayne

 

[orionrider]

Hi MW,

I saw a nice one the day before yesterday while scanning the skies for M13 in my binocular. It was about mag 7, invisible with unaided eyes. The light was flashing at about 1Hz. Definitely not a plane, too faint, too fast and no other lights. Maybe some space junk tumbling.

 

[Esper_Ranger]

Re: Twin satellites?

Thanks for the answer. That may be what I was looking at but I'll have to check up on the list to see if I can duplicate the sighting. Like I said, they seemed a lot closer than 5 or 6 seconds apart. They were right together as if the one behind were drafting or tailgating even though I realize that in space they may have been several miles apart.

 

[adrenalynn]

Re: Twin satellites?

They may have been many many miles apart. That altitude is far past the vanishing point, so depth perception is nil.

Two airplanes can look like they're going to crash into each other, but may be a couple miles apart just in depth.

 

[MeteorWayne]

Re: Twin satellites?

Thanks for the answer. That may be what I was looking at but I'll have to check up on the list to see if I can duplicate the sighting. Like I said, they seemed a lot closer than 5 or 6 seconds apart. They were right together as if the one behind were drafting or tailgating even though I realize that in space they may have been several miles apart.

I may have seemed like it, but I'll bet if you timed it, it would be closer to 5 seconds than you think

Supposed to be cloudy here tonight, but tomorrow night should be wonderful, so I'll take a look as well

A few notes on Heaven's-Above.

The least accurate info in the chart is the magnitude (brightness) prediction. I saw Cosmos 2297 this morning that was supposed to be +1.4, it was actually dimmer than +3.5. Perhaps the satellite was aligned in a non-optimum way.
Another thing to realize is that the listed magnitude is the brightest along the path. Closer to the horizon, it will be fainter since you are looking through more atmosphere.

The orbits are usually pretty close, depending on how recently the orbit has been updated (The orbit "Epoch"). Currently the NOSS Sat's Epoch is Sept 5, so should be very accurate (Only 2 days old).

Always look a few minutes early and late in case the timing is off a bit.

Wayne

BTW, I have merged this into the satellite observation descussion.

 

[rtphokie]

prediction formulas?

There are a ton of apps for the iPhone and Android as well as websites like heavens-above that make satellite pass predictions available. They rarely line up so I doubt they are all pulling form a single source like heavens-above. Where are they getting their formulas from?

Can someone point me to a formula which takes the TLEs and the observers longitude and latitude as input and produces at least rise times, azimuth and maximum elevation? I'd love to see the math behind these predictions.

 

[MeteorWayne]

It's all basic math from the TLE's, and they all should use the same ones. Perhaps others don't update as often. You can always tell on Heaven's-Above what the date of the elements used is; it's on the page if you click on the pass time. As well as the actual TLE's.

 

[rtphokie]

It's all basic math from the TLE's, and they all should use the same ones. Perhaps others don't update as often. You can always tell on Heaven's-Above what the date of the elements used is; it's on the page if you click on the pass time. As well as the actual TLE's.

Can you point me to an example of the formula used with those TLE's?

 

[MeteorWayne]

Sorry, I don't have any handy.
It's not simple, there's a lot of info buried in the TLEs.

 

[adrenalynn]

Faaaar too complex to try to get into on a forum that doesn't even have proper math notation.

Work through this: http://www.coastalbend.edu/acdem/math/c ... /index.htm translating as appropriate for your programmable calculator or TI emulator on the PC.

 

[MeteorWayne]

Sat report for the last 2 mornings...

I've been out meteor observing the last two mornings between moonset and dawn to catch some Orionids. During ~ 6 hours (roughly 3-6 AM each morn) I've seen 11 satellites, one of them twice!

The one I saw twice is a geostationary sat, with a "flare" lasting about half an hour. I wasn't sure yesterday, since I just noticed a star that didn't belong there, not far from Mira, which is also invisible most of the time, so I was confused. So this morning I watched more closely, and could clearly detect the 1 degree every 4 minute motion of the stars behind it. One thing about meteor observing; you spend a lot of time staring at the constellations, so you notice when someting appears that doesn't belong there.

Yesterday, my meteor session ended at 5:49 AM, and as I was packing up, the ISS came blazing over the tree line to the north, heading northeast. It was about mag -3, and slowly faded as it headed twoard the direction of the sunrise.

Of the other 9 sats, 5 were "normal" fixed brightness, one faded from mag +2.5 to invisibility, one slowly varied in brightness, invisible for a while then reaching about mag +3.5. I also had one flasher, with a 9 second period yesterday, and a very interesting fast moving complex flasher this morning. The main period was about 3 seconds, but between the bright flashes there were 4-6 other fainter flashes, that didn't exactly repeat for each period.

Lot's of interesting stuff up there, if you "Keep Looking Up"
(Thanx, Jack )

 

[orionrider]

Nice report, thanks!
The night is so full of them that I can't take a stack of pictures without having some crossing the field.
Between the sats, the meteors, the airliners, the occasional UFO and disco green lasers it is becoming increasingly difficult to picture the sky...

the ISS [...] was about mag -3

Can you imagine future giant space stations, kilometers long? Shining brighter than Venus? Maybe -10? They say Iridium flares can reach -9.5 :shock:

That's gonna be a nuisance for meteor watchers and astronomers alike, but what an awesome sight!

 

[brandbll]

So yesterday in Saint Paul, Minnesota, USA my roommate and I were standing outside and saw what appeared to be two satellites almost crossing the exact same paths. One was going north, the other going south. The southbound sattelite appearing a little before the northbound sattelite. They both disappeared behind clouds rather quickly so we didn't get to watch them for long. Now i looked on Heavens-above and entered my exact location. The only satellite that shows up for that exact time was the Gurwin Techsat B. The only other satellite around that time going in the southbound direction was JAS-2. However, the times don't line up like they should. Is it just a slight miscalculation by Heavens-above or could it be another satellite they don't have listed under their radio ameteur section? BTW, neither was very close to the horizon.

 

[orionrider]

Can be anything: dead sat, spy sat, lost toolkit, torn solar panel, forgotten booster stage,...
Lots of space junk out there...

 

[MeteorWayne]

I can only ID about 75% of the satellites I see using Heavens-Above. And I keep very accurate notes during my meteor session with path (both altitude & azimuth, and stars it passes), magnitude, as well as time accurate to the second.

I find magnitude (brightness) to be the least accurate prediction based on my obs, so it's possible a sat that was predicted to be dimmer than +4.5 (which would not be listed) turned out to be brighter.

Under very dark skies of course, you can see mainy fainter sats than what they list.

 

[MeteorWayne]

Nice neckbreaker (nearly overhead) pass of the ISS in about 18 minutes for the northeast US (7:12-7:16 EDT) from WSW to NE...

MW

 

[MeteorWayne]

Finally spotted the X-37B last night!!

Yes, it's real