Wednesday, March 21, 2012

Footage of a pass of the KH-12 Keyhole optical reconnaissance satellite USA 129



Spring is a time when not only some birds appear out of their winter hiding, but some satellites emerge from winter darkness as well. Among them the evening plane KH-12 "Improved Crystal" Keyhole satellites.

The footage above shows one of these evening plane KH-12 Keyholes, USA 129 (96-072A), the oldest one still in orbit. The footage was shot by me in the evening of Monday 19 March, from my observatory in Leiden. The star field is a part of the tail of the Big Dipper: epsilon Uma at lower left and delta Uma at upper left. A WATEC 902H camera, GPS time inserter and Canon EF 2.0/35mm lens were used.

USA 129 was quite bright during this pass and well visible by the naked eye: initially near magnitude zero in Leo, then near magnitude +2.5 once culminating near Uma (the segment of footage shows it while it was near +2.5.)

The Keyholes are optical reconnaissance satellites, resembling Hubble Space Telescopes pointing to Earth surface. They image the earth with a resolution that is believed to be in the order of 10 centimeters (about 4 inch). Four of them are in orbit currently: USA 129 imaged above, USA 161, USA 186 and USA 224. USA 186 is an evening plane Keyhole just like USA 129: the other two are midnight plane Keyholes. On my 52 degree latitude, the evening plane Keyholes start to make visible evening passes in March, the midnight plane Keyholes during the late spring and summer (starting April-May).

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