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Same satelite twice???



 
 
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  #1  
Old October 17th 11, 03:41 AM
swc swc is offline
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First recorded activity by SpaceBanter: Oct 2011
Posts: 1
Default Same satelite twice???

Hey guys/girls I am new to this site so first of I would like to say the image verification to register may be the most ridiculous/hardest thing I have witnessed in my life, it only took me 15 tries to get it right (rather annoying). Anyways I was sitting in my hot tub tonight staring up at the stars when I noticed a fairly fast paced bright object moving south it went really bright and then dimmed out and I could no longer follow it. About 15 minutes later the same object appeared in the exact same spot only dimmer than the first time and steadily got dimmer till it vanished. Can someone explain what is happening? If this is the same object I seen 15minutes earlier why does it progressively become dimmer as it goes away, and why was it dimmer the 2nd time I seen it even though it was in the exact same spot? Hopefully this is not to confusing I am know space major / science genius, its rather interesting to me though.
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  #2  
Old October 17th 11, 06:27 PM posted to sci.astro.satellites.visual-observe
Patty Winter
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Posts: 38
Default Same satelite twice???


In article ,
swc wrote:

Hey guys/girls I am new to this site so first of I would like to say the
image verification to register may be the most ridiculous/hardest thing
I have witnessed in my life, it only took me 15 tries to get it right
(rather annoying).


Hello, swc. This isn't a "site," it's a Usenet newsgroup. It sounds
like you may be viewing the group through a gateway to a website. If
so, you can get yourself free Usenet software (search for "newsreader"
and whatever computer platform you use) and even a free Usenet account
and read all the newsgroups you want without going through a website.


Anyways I was sitting in my hot tub tonight staring
up at the stars when I noticed a fairly fast paced bright object moving
south it went really bright and then dimmed out and I could no longer
follow it. About 15 minutes later the same object appeared in the exact
same spot only dimmer than the first time and steadily got dimmer till
it vanished. Can someone explain what is happening?


That wasn't the same object; it was two objects in the same orbit. A
satellite in low earth orbit typically takes about 90 minutes to come
around again.

If you saw each one for only 5-10 seconds, they may have been Iridium
satellites. Otherwise, it was probably two parts of a single spacecraft,
and I don't recall which spacecraft have that situation. Perhaps someone
else here will know.


Patty

  #3  
Old October 19th 11, 10:42 PM posted to sci.astro.satellites.visual-observe
DougD
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Posts: 19
Default Same satelite twice???

In article , Patty Winter wrote:

Anyways I was sitting in my hot tub tonight staring
up at the stars when I noticed a fairly fast paced bright object moving
south it went really bright and then dimmed out and I could no longer
follow it. About 15 minutes later the same object appeared in the exact
same spot only dimmer than the first time and steadily got dimmer till
it vanished. Can someone explain what is happening?


That wasn't the same object; it was two objects in the same orbit. A
satellite in low earth orbit typically takes about 90 minutes to come
around again.

If you saw each one for only 5-10 seconds, they may have been Iridium
satellites. Otherwise, it was probably two parts of a single spacecraft,
and I don't recall which spacecraft have that situation. Perhaps someone
else here will know.


Patty


To add to this, it could have also been a pair of satellites from a group,
such as the NOSS, which can be spotted one, two or three in a group,
or sometimes one after the other. OR, as Patty pointed out, it could be
parts of one object that has broken into two, or say a satellite and
the rocket booster that put it in orbit. The change in brightness could
be from all sorts of reasons, the first that comes to mind is even though
it was only 15 minutes of difference, your location relative to the Sun,
which is what is illuminating the object that you are seeing have changed
over that amount of time. So, as the Sun moves away or approaches you,
the brightness will change relative to the sat's position between you and
the Sun and the distance and angles that is it's path. Not the most
elegant explanation, but I think you'll get it..

d.
  #4  
Old October 19th 11, 10:56 PM posted to sci.astro.satellites.visual-observe
Patty Winter
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Posts: 38
Default Same satelite twice???


In article , DougD wrote:

To add to this, it could have also been a pair of satellites from a group,
such as the NOSS, which can be spotted one, two or three in a group,
or sometimes one after the other.


Ah, right, I'd forgotten about NOSS.

I've seen two Iridii a minute apart, same path.


The change in brightness could
be from all sorts of reasons, the first that comes to mind is even though
it was only 15 minutes of difference, your location relative to the Sun,
which is what is illuminating the object that you are seeing have changed
over that amount of time.


Or perhaps even more likely, the second piece was smaller than the
first?

Forgot to mention this to the original poster, but on Heavens-Above
(http://www.heavens-above.com), it's easy to plug one's location into
the site and find out what went over at a specific time. You can even
back up a few days by using the "Prev" link.


Patty

  #5  
Old October 23rd 11, 01:46 AM posted to sci.astro.satellites.visual-observe
Me
external usenet poster
 
Posts: 1
Default Same satelite twice???

The change in brightness could
be from all sorts of reasons, the first that comes to mind is even though
it was only 15 minutes of difference, your location relative to the Sun,
which is what is illuminating the object that you are seeing have changed
over that amount of time.


Or perhaps even more likely, the second piece was smaller than the
first?


out of curiosity, could it be two totally unrelated satellites, on two
different orbits?

Jean
  #6  
Old October 26th 11, 04:13 PM posted to sci.astro.satellites.visual-observe
DougD
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Posts: 19
Default Same satelite twice???

In article , Me wrote:
The change in brightness could
be from all sorts of reasons, the first that comes to mind is even though
it was only 15 minutes of difference, your location relative to the Sun,
which is what is illuminating the object that you are seeing have changed
over that amount of time.


Or perhaps even more likely, the second piece was smaller than the
first?


out of curiosity, could it be two totally unrelated satellites, on two
different orbits?

Jean


Yes, I've seen an Iridium and another satellite appear to travel on the same
path a few minutes apart. I went back and looked at the actual orbits using
Starry Night, etc. and they really weren't even that close in orbit, but the
eye and brain fill in the blanks in different ways to make them appear close.
Whether they would both flare would be a bit unusual, unless they were
both Iridiums,

d.
  #7  
Old October 27th 11, 04:26 AM posted to sci.astro.satellites.visual-observe
Skywise
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Posts: 318
Default Same satelite twice???

(DougD) wrote in :

In article , Me wrote:
The change in brightness could
be from all sorts of reasons, the first that comes to mind is even
though it was only 15 minutes of difference, your location relative
to the Sun, which is what is illuminating the object that you are
seeing have changed over that amount of time.

Or perhaps even more likely, the second piece was smaller than the
first?


out of curiosity, could it be two totally unrelated satellites, on two
different orbits?

Jean


Yes, I've seen an Iridium and another satellite appear to travel on the
same path a few minutes apart. I went back and looked at the actual
orbits using Starry Night, etc. and they really weren't even that close
in orbit, but the eye and brain fill in the blanks in different ways to
make them appear close. Whether they would both flare would be a bit
unusual, unless they were both Iridiums,


What about a spare Iridium? Are there not spares in the same
orbital plane, just at a slightly different altitude? I seem
to recall hearing of 'double flares' caused by an operational
sat and a spare following/preceding.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?
  #8  
Old October 29th 11, 01:31 AM posted to sci.astro.satellites.visual-observe
Merv
external usenet poster
 
Posts: 3
Default Same satelite twice???

You say, "the same object" Why?
The likelihood is that all you saw was another satellite travelling
in the first satellite's path. This is often the case.

Minge


On 17/10/2011 1:11 PM, swc wrote:
Hey guys/girls I am new to this site so first of I would like to say the
image verification to register may be the most ridiculous/hardest thing
I have witnessed in my life, it only took me 15 tries to get it right
(rather annoying). Anyways I was sitting in my hot tub tonight staring
up at the stars when I noticed a fairly fast paced bright object moving
south it went really bright and then dimmed out and I could no longer
follow it. About 15 minutes later the same object appeared in the exact
same spot only dimmer than the first time and steadily got dimmer till
it vanished. Can someone explain what is happening? If this is the same
object I seen 15minutes earlier why does it progressively become dimmer
as it goes away, and why was it dimmer the 2nd time I seen it even
though it was in the exact same spot? Hopefully this is not to confusing
I am know space major / science genius, its rather interesting to me
though.





  #9  
Old November 2nd 11, 04:17 AM posted to sci.astro.satellites.visual-observe
DougD
external usenet poster
 
Posts: 19
Default Same satelite twice???

In article , Skywise wrote:

What about a spare Iridium? Are there not spares in the same
orbital plane, just at a slightly different altitude? I seem
to recall hearing of 'double flares' caused by an operational
sat and a spare following/preceding.

Brian


Good point! I guess they have to park the spares somewhere, would guess that
they use some logic to figure what sat is next to fail and keep a spare
nearby. Not sure if a spare is fully deployed, most likely is, so would also
be able to flare..

d.
  #10  
Old March 28th 13, 11:14 PM
RichardF RichardF is offline
Junior Member
 
First recorded activity by SpaceBanter: Mar 2013
Posts: 4
Default

Quote:
Originally Posted by swc View Post
I noticed a fairly fast paced bright object moving south it went really bright and then dimmed out and I could no longer follow it. About 15 minutes later the same object appeared in the exact same spot only dimmer than the first time and steadily got dimmer till it vanished.
Firstly it's normal that satellites dim out as they go south -- that's because they are moving into the Earth's shadow and when they're not illuminated you can't see them anymore. It's also normal that the brightness varies, and not just for the mirror-like iridium flares. This is because, even when the satellite is in sunlight, you can be looking at the side which is in shadow.

Also, it's extraordinarily difficult to say that a satellite has passed inexactly the same spot, even if you're using the stars as a reference. More likely, you were seeing two satellites in sun-synchronous orbit. These have approximately the same inclination, and so would follow the same path, possibly offset a bit to the east or west. there are loads of such satellites, so this is not uncommon at all.

cheers,
Richard
 




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