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PostPosted: Sat Feb 26, 2011 9:41 pm 
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Location: 55° 57'N: 03° 08'W
On the 18.36 U.T. pass they were about 1 arcmin apart, with the fainter
shuttle leading the pair. By the second pass they were linked, and I tried to
follow them after eclipse entry, using any internal lights but was not
able to detect them i. e. they would be fainter than mag +8.


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PostPosted: Sun Feb 27, 2011 10:39 am 
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Location: Goosnargh, north of Preston, UK
stella wrote:
On the 18.36 U.T. pass they were about 1 arcmin apart, with the fainter shuttle leading the pair. By the second pass they were linked, and I tried to follow them after eclipse entry, using any internal lights but was not able to detect them i. e. they would be fainter than mag +8.


Thanks stella.

I'm a bit rusty on arc minutes, so I've just looked up the details for Mizar and Alcor, the easy visual double in Ursa Major. The Cambridge Star Atlas list them as being separated by 708.7 arc seconds, or 11.8 arc minutes.

For the first pass I forgot to take my spectacles with me, but I enjoyed it all the same. For the second pass I managed to look in the wrong direction altogether.... :oops:

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PostPosted: Sun Feb 27, 2011 10:50 am 
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Location: Sheffield (53° 21' N 1° 12' W)
Hi,
According to the 'Spaceflight Now' updates at 18.34 UT. the ISS and Discovery were 470 ft. apart. (now if I had only known that at the time :roll:)
All the best.
Dave

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PostPosted: Sun Feb 27, 2011 12:48 pm 
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470feet equals 1/11 mile. Overhead ISS ? 250miles so one part in 2750, say 1.2 arcminutes separation. At slant range 350 miles about 0.9 arcminutes.
With equal stars say mag3in dark sky it needs excellent vision to achieve 2.5 arcminute resolution of equal stars.
With two such bright unequal 'stars' children might separate them at 3.5 to 4 arcminutes. With older yes with aberrations I would think 5 arcminutes more likely.
So there is no way anything but an eagle could separate the ISS and Shuttle yesterday. Possibly a Hawk. Ordinary human no except with optical aid.

Should say eyes above.
When young I could separate epsilon Lyrae with unaided eye from memory only about 3.5 arcminutes but fainter than ideal.
Regards, David.


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PostPosted: Sun Feb 27, 2011 1:08 pm 
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Location: 55° 57'N: 03° 08'W
...except with optical aid.

I was using 11x80 binoculars which enabled them to be seen
in close conjunction.
The stars nu1 and nu2 Draconis are about the same separation,
so you can test this for yourself.
You may also like to try psi Draconis which I think is a closer double.


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PostPosted: Sun Feb 27, 2011 2:21 pm 
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Thanks Stella, You did very well to see the two. Unfortunately because of the predictions and my back I did not use my binoculars. There was a chance when highest at about 60 degrees for me to se them, but looking through the window at that elevation would be a big strain for me and there was signicant clod then, which actually in this situation might have helped to reduce glare.

Should say significant cloud, it is actually fairly difficulf for me to type because of back problems, that is why I make so many mistakes.
The south east facing window when highest was O.K. unaided eye.

I just checked height of ISS and it was about 220miles so it would have been about 1.4 arc minutes overhead and 1.0 minute at a slant distance of say 320miles.

Regards, David


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PostPosted: Sun Feb 27, 2011 2:52 pm 
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Location: 55° 57'N: 03° 08'W
Here's an beautiful image taken by Rob Bullen at just about the same time:

http://www.spaceweather.com/submissions ... 758133.jpg

(if that link doesn't work, just go to spaceweather.com


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PostPosted: Sun Feb 27, 2011 3:43 pm 
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Location: Sheffield (53° 21' N 1° 12' W)
Hi stella,
Thats a stunning image, incredible. As Rob Bullen said, "a once in a lifetime image".
Thanks for sharing the link with us.
All the best
Dave

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PostPosted: Sun Feb 27, 2011 8:33 pm 
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Hi,
I think quite a few people were thrown by the HA predictions
I have just compared the upcoming HA predictions for the ISS (Shuttle predictions still not updated) with the CalSky predictions and they are very much the same but CalSky is up to date with the Shuttle passes (although now docked it gives the Shuttle pass times for the passes after undocking on Sat 5th March 12.44 UT).
This site has a wealth of information including ISS transit times (Sun/Moon), as well as plenty of other useful/interesting info.
Might still get to see a seperated Shuttle on Sat 5th and Sun 6th evenings. Will be worth re-checking the pass times nearer the dates.
All the best
Dave

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PostPosted: Thu Mar 03, 2011 11:37 am 
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Location: Sheffield (53° 21' N 1° 12' W)
Hi,
Due to the Shuttle mission being extended by a day the Shuttle can be seen (hopefully) on the evenings of 6th and 7th March. Best to check timings nearer the date on HA and CalSky. According to Calsky (depending on your location) there is a chance of observing the ISS and Discovery transitting the Moon separately 7th March at 17.48 UT (ISS) and 17.49 UT (Discovery). These times are for my location and the Moon will be a thin crescent so will be a real challenge to observe/photograph. Best to keep checking the times.
Undocking is due on 6th March 11.38 UT. and the landing is scheduelled for 8th March 16.36 UT. Best to keep checking the times.
All the best
Dave

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PostPosted: Thu Mar 03, 2011 1:37 pm 
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Would a transitting ISS or Shuttle be visible in binoculars?

David.


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PostPosted: Thu Mar 03, 2011 2:13 pm 
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Hi David,
The Moon will be a very slender crescent and the transit across the disc will be around a second. Might (?) be able to observe the transits although the Shuttle wont be very bright. I was wondering if anyone would attempt a scope/webcam image.
The following is info for my location for the Shuttle (CalSky)

Monday 7 March 2011 Time Object (Link) Event
17h49m09.66s [Space Shuttle] STS-133 Space Shuttle Crosses the disk of Moon. Separation=0.112° Position Angle=178.8°. Transit duration=0.96s
Satellite at Azimuth=248.7° WSW Altitude= 28.1° Distance=699.6 km Magnitude=6.3mag
In a clock-face concept, the satellite will seem to move toward 10:11
Angular Velocity=27.2'/s

Centerline, closest point →Map: Longitude= 1°13'10"W Latitude=+53°20'13" (WGS84) Distance=1.91 km Azimuth=191.9° SSW Path direction=101.9° ESE ground speed=8.269 km/s width=6.4 km max. duration=1.1 s
Sun elevation=+0° Elongation from Sun=32°
Orbit source: NASA predicted orbit

ISS

Time Object (Link) Event
17h48m53.83s [International Space Station] ISS Crosses the disk of Moon. Separation=0.141° Position Angle=178.8°. Transit duration=0.88s
Angular diameter=26.5" size=73.0m x 44.5m x 27.5m
Satellite at Azimuth=248.6° WSW Altitude= 28.1° Distance=697.7 km Magnitude=-0.7mag
In a clock-face concept, the satellite will seem to move toward 10:11
Angular Velocity=27.3'/s

Centerline, closest point →Map: Longitude= 1°13'16"W Latitude=+53°19'58" (WGS84) Distance=2.40 km Azimuth=191.9° SSW Path direction=101.9° ESE ground speed=8.265 km/s width=6.4 km max. duration=1.1 s
Sun elevation=+0° Elongation from Sun=32°
Orbit source: NASA predicted orbit
17h50m00s [International Space Station] ISS
→Ground track →Star chart [Daylight pass] Appears 17h45m07s 3.3mag az:275.9° W horizon
Culmination 17h50m00s -3.1mag az:196.3° SSW h:42.6°
distance: 510.9km height above Earth: 356.5km elevation of sun: +0°
Disappears 17h54m52s -1.0mag az:116.7° ESE horizon

All the best
Dave

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PostPosted: Thu Mar 03, 2011 3:27 pm 
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Should be visible in binoculars at least ISS.

I often see aircraft crossing the Sun in PST early in morning. Usually takes about one or two seconds. Because I can usually identify the type from its outline I know the wingspan and length and can estimate the height and distance from the angle of the PST.
They are often at cruising altitude around 35,000 feet. sometimes around 60miles distance.
They leave two very black contrails which disturb the solar image for several seconds.
I have probably seen this a hundred times or so.

Sometimes they are much closer in and occupy much more of the solar disc.

The magnification is 32x and seen to the south east.
I sometimes see two within the space of a few minutes.

Regards, David.


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PostPosted: Thu Mar 03, 2011 5:01 pm 
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In the cruise where I see them the aircraft are usually at 520mmph plus or minus wind speed.
In the descent 210 to 260mph plus or minus wind speed which is usually less than at cruising height.

The aircraft are upside down.

I rarely see 4 engined aircraft, maybe because long haul flights are in different direction from me.

The contrails last up to say ten seconds silouetted against the Sun and they spread out sideways and also drift away in the wind.

In a way it is strange to see ircraft silouetted against an H alpha Sun.

The aircraft appear either from the left or right and the tracks usually mean they are more or less at right angles to me.

Very enjoyable for me.

David.

I verey often also see birds silouetted against the Sun, near and far.


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PostPosted: Thu Mar 03, 2011 5:28 pm 
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In the descent from where I see them the wind is usually south west or westerly.
So the ground speed is less than the airspeed, which means it takes a bit longer for the aircraft to cross the Sun's face.

At cruising height the wind can be any direction but is more likely to be ftrom the west.

David.


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