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 Post subject: ISS IN DAYTIME
PostPosted: Thu Jan 28, 2010 6:54 am 
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Location: Mumbai / Abu Dhabi
I watched ISS in daytime, yesterday. Details as below,

Date : 07 Jan, 2010. Time : 14:17 UTC
Location : Ruwais UAE (24:05:15 N, -52:38:07E)

Sunset : 14:12:39 UTC
Sun altitude @ 14:17:00 UTC is -0d:57m:27s

TLE FOR ISS (ZARYA) DATA TAKEN FROM CELESTRAK / NORAD site updated on 28/01/2010.

1 25544U 98067A 10027.90972940 .00014091 00000-0 94709-4 0 4612
2 25544 51.6441 231.0513 0010956 250.4431 250.8411 15.75441770641371

Sun had just set, broad daylight was still available. ISS was sighted when it was descending from max altitude (74d) at ~35d. Its visual mag was estimated to be -2.0, but it suddenly dropped to ~0.5 within seconds. Watched for some 20 seconds before it difficult to watch it due to daylight.

Vikas


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PostPosted: Mon Feb 01, 2010 8:40 am 
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Location: Sheffield (53° 21' N 1° 12' W)
Well done Kharat

Never seen a daylight pass (tried many times)

Was a pass for me this morning 08.02 UT clear sky and the Sun was still low but no luck (I knew it was passing as my scanner was picking a signal up).
All the best.
Dave

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 Post subject:
PostPosted: Mon Feb 01, 2010 9:47 am 
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thanks,

It's very difficult. By the way, in your opinion which should be called a day sighting (in terms of CIVIL DAY / NAUTICAL DAY / ASTRONOMICAL DAY)? This question was bothering me since sighting and posting.

Vikas.


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PostPosted: Mon Feb 01, 2010 11:53 am 
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Location: Sheffield (53° 21' N 1° 12' W)
kharat wrote:
thanks,

It's very difficult. By the way, in your opinion which should be called a day sighting (in terms of CIVIL DAY / NAUTICAL DAY / ASTRONOMICAL DAY)? This question was bothering me since sighting and posting.

Vikas.


Hi,

Obviously as I live in the UK I use UT time which is the same as GMT until British Summer Ttime starts in our springtime.
Check this out
http://www.heavens-above.com/
Simple to register (enter your location) and will give you all the info/timings you will need.
Hope this helps.
All the best
Dave

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 Post subject:
PostPosted: Mon Apr 26, 2010 9:30 am 
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Location: Mumbai / Abu Dhabi
Below is my second sighting of ISS in daytime (sun's altitude less than minus 6 deg).

Satellite: ISS (1998-067-A)

Time (UTC): 26-Apr-2010, 01:29:00.000 +/- 0.2secs

Site: Ruwais, Abu Dhabi (24.0877N, 52.6781E, 10 metres)

Observer: Vikas Kharat, ISS daytime

Comments: (Day Sighting # 2) Spotted ISS. Track, time as predicted. Spotted as 25 deg alt as twilight is out and just is 5 deg below horizon. Vmag +1.0 to +1.5, watched for two minutes. This is the TLE taken from celestrak website. ISS (ZARYA) @ 0400 UTC - 26 April, 2010. (Line1) 25544U 98067A 10115.85025463 .00015165 00000-0 11119-3 0 424 (Line2) 25544 51.6455 139.1703 0009837 238.1310 119.6559 15.73344628655226


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 Post subject:
PostPosted: Sat May 01, 2010 1:24 pm 
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Location: Mumbai / Abu Dhabi
Below is record of my third daytime sighting.

Track, time as predicted by great software xephem.

TLE was downloaded from celstrak website at 1430 UTC as for prediction. Below is the TLE DOWNLOADED AT 1510 UTC for ISS (ZARYA)
<line1> 25544U 98067A 10120.31994691 .00011580 00000-0 85595-4 0 640<br>
<line2> 25544 51.6440 116.2403 0009817 255.5489 236.7311 15.73456889655939.

Watched for some 30 second sitting at door of my camp's cabin, while ISS falling part from alt 52 09 47 ( Sun +00 57 52) at 145238 UTC to 41 37 47 (Sun +00 52 06) at 145308 UTC.

This sighting was better than Jan 27 sighting, though this time vmag was lesser, as this time Sun has not actually set.

Xephem is a great help, in pursuing day sighting.

Vikas.


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PostPosted: Sat May 01, 2010 3:18 pm 
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Hi Vikas,
Well captured. I have never seen the ISS in full daylight but many times in twighlight just after the Sun has set.
More info on the three time methods you mentioned (reguarding twighlight) can be found here.

http://en.wikipedia.org/wiki/Twilight

All the best.
Dave

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 Post subject:
PostPosted: Mon May 03, 2010 9:28 am 
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Davej,

Thanks.

If an observation is made when the sun is less than six degree below horizon, then in my pushing observation in HA database, i decide to call it a daytime observation.

You must have got it that way also, mustn't you?

Vikas.


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 Post subject:
PostPosted: Mon May 03, 2010 1:58 pm 
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Location: Sheffield (53° 21' N 1° 12' W)
kharat wrote:
Davej,

Thanks.

If an observation is made when the sun is less than six degree below horizon, then in my pushing observation in HA database, i decide to call it a daytime observation.

You must have got it that way also, mustn't you?

Vikas.


Hi Kharat,

I agree with what you are saying but I was thinking along the lines of calling it a daytime sighting whilst the Sun was still above the horizon.
I have never seen one of these sightings but quite a few like your daytime observations.

All the best.
Dave

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 Post subject:
PostPosted: Tue May 04, 2010 6:03 am 
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Hi Dave,

It would be too hard to locate ISS in braod daylight when the Sun is more that a couple of degree above the horizon. Persistance would be needed on the part of observer, as in my opinion, roughly, there could be 75 passes for a location in a year in twilight condition and may be 6 to 12 passes in year when the sun is couple of degree above the horizon. This all is to be depreciated for local weather conditions.

Thanks and all the best.
Vikas.


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 Post subject:
PostPosted: Tue May 04, 2010 7:27 am 
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Location: Sheffield (53° 21' N 1° 12' W)
Hi,

Actually I think it is possible to see the ISS when the Sun is above the horizon, it's just knowing where to look.
I have read quite a few reports of sightings, heres one...
http://www.universetoday.com/2009/06/17 ... n-daytime/
Conditions would have to be very good though :)

All the best
Dave

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 Post subject:
PostPosted: Tue May 04, 2010 8:20 am 
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Location: Mumbai / Abu Dhabi
Hi Dave,

I remember reading this piece of news at spaceweather DOT com. After reading this news I had created a test location in my login account in HA for chorlotte, USA, and found that there wasn't agreeable passes of ISS for the time and location.

Someone else has also done this checking and posted same opinon at the lower part of the web page (you linked). Even if we consider filtering policy (in terms of altitude) of HA, and assume that there was a pass, then also altitude in the photograph looks unagreeable.

After reading this news I had intensified my effort locating ISS in broad daylight but failed every time (my other posts in this forum).

All the best.

Vikas.


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 Post subject:
PostPosted: Thu Mar 01, 2012 8:21 am 
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I have attempted to capture ISS in daylight for many years now, and I can confirm just how difficult it is , Denim Pine especially with no point of reference. I wasn't able to get a sharp image, but, good fun trying anyway.


Last edited by carlos08 on Thu Jul 18, 2013 4:33 pm, edited 2 times in total.

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 Post subject:
PostPosted: Tue Mar 06, 2012 11:38 am 
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Can anyone tell me if there is a site somewhere which can give pass details,
similar to those on Heavens Above which seem only to be for nighttime
passes, but for daytime as well?


Last edited by Zema0982 on Thu Jan 10, 2013 7:27 am, edited 2 times in total.

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 Post subject:
PostPosted: Tue Mar 06, 2012 1:19 pm 
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Location: 55° 57'N: 03° 08'W
It depends in which reference frame you want the predictions.
Clearly R.A. and Dec. are unusable due to lack of stars, etc in the
daytime sky.


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