Monday, 29 November 2010

PAN and other geostationary satellites in a frosty winter sky

Last Sunday evening, the pass of the Terra SAR X and Tandem X close duo posted earlier here and a pass of Lacrosse 4 shortly after that, were not the only observations I made. Somewhat later that night, I targetted several geostationary satellites, using both the Canon EF 2.5/50 mm Macro lens and the Carl Zeiss Jena Sonnar MC 2.8/180 mm lens (the latter for the first time on geostationary objects).

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The image above, taken with the EF 2.5/50mm lens, shows two geostationary objects close to the Orion nebula.

One is the classified object USA 202/Mentor 4 (2009-001A), a big SIGINT geostationary satellite with a brightness of about mag. +8. It has featured on this observing blog earlier. The other one, Galaxy 8 (1997-078A), is a commercial communications satellite and was captured serendipitously in the same image while it was brightly but briefly flashing. It is not visible in an image taken 30 seconds later (and only faintly visible in an image taken 3.5 minutes earlier).

I also imaged the mysterious classified geostationary PAN (2009-047A) for the first time, using the new Carl Zeiss Jena Sonnar MC 2.8/180 mm lens. Below image shows it together with the nearby commercial geostationary satellites Paksat 1 (1996-006A) and Hellas-sat 2 (2003-020A).

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PAN is a very mysterious object, the mysteries surrounding the 2009 launch being discussed at length by Dwayne Day in his Space Review article here. The mystery was (and is), that no Agency (neither NRO, USAF, US Navy nor CIA) claimed responsibility for the launch. Owner and role are hence unknown. There was much speculation about the possible role of the spacecraft, and the meaning of the acronym PAN. The latter got at least one "solution" when the launch patch (below) appeared, suggesting PAN stood for "Palladium At Night". Whatever that may mean.

The same images that contained PAN, Paksat and Hellas-sat 2 also contained the very faint trail of a Breeze-M tank (2009-050C) and two more geostationary satellites: Eutelsat W4 and Eutelsat W7 (2000-028A and 2009-065A). This all in an image only a few degrees wide!

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Last but not least, the classified geostationary communicatiosn satellite Milstar 5 (2002-001A) was imaged. In the same image(s), two other, commercial geostationary satellites were visible: Galaxy 11 (1999-071A) and Inmarsat 4-F2 (2005-044A). A rich haul of geostationary objects, obtained at mildly frosty temperatures of -2.5 C!

Terra SAR X and Tandem X flying in formation (and flaring!)

Over the past months, the two German remote sensing research satellites Tandem X and Terra SAR X (2010-030A and 2007-026A) operated by the German agency DLR have been manoeuvred to form a very tight formation, cruising up together with a distance of no more than a few hundred meters.

This provides a very nice sight for observers, especially since both satellites also produce slow, naked eye flares when the sun-satellite-observer angle is favourable.

Yesterday evening near the end of twilight, I had a favourable pass, with the duo cruising through the zenith at an altitude of around 515 km. They flared while they did this, to mag. +1, at about 17:01:15 UTC (28 Nov), give or take a few seconds. My camera opened just a few seconds after the flare peak, and captured the pair while slowly fading in this 10 second image:

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Movement is from bottom right to upper left. I measure a distance of 70 arcseconds (or just over 1 arcminute) between the two objects on this image, corresponding at face value to about 175 meter distance. But because there is a small altitude difference between the two objects as well, the true separation between the two is a bit more than this value. Terra SAR X (2007-026A) is the slightly leading and slightly brighter object in the formation.

Thursday, 18 November 2010

Senegalese skies

I spent the first half of this month in Africa, in Senegal, where I took part in the 2010 PANAF/Safa conference (PANAF = Pan-African Archaeology Conference) in Dakar. After the conference my girlfriend, two friends/colleagues and me added a few days of tourism through the country.

During the conference field excursion to the Saloum delta, and later during our private trip to the Lompoul sand dunes, I took a few shots of the Senegalese night sky. I didn't have my regular astrophoto lenses with me, so used my Tamron 2.8/17-50 mm zoom (not an ideal choice for astrophotography) at 17mm. The camera was fixed on a tripod, no guiding, exposure times ranged between 10 and 20 seconds, ISO 1600.

Below are some of the resulting pictures, plus a photograph of me taken at a megalithic site during the conference field excursion.

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