Thursday, 16 March 2017

USA 186 recovered

click to enlarge

The image above shows USA 186 (2005-042A), a KH-11 ADVANCED CRYSTAL ("Keyhole") optical reconnaissance satellite. It is cruising just below the Pleiades star cluster in this image, which I shot yesterday evening using the Samyang 1.4/85 mm lens and an exposure of 2 seconds.

USA 186 was recovered last week after being briefly lost in the Northern hemisphere winter blackout. Leo Barhorst made one or two possible detection in February, but it was Cees Bassa who unambiguously recovered it on March 13th. Two days later, I made the image above.

The arc is still short, but it appears to be in an approximately 265 x 435 km sun-synchronous orbit. The apogee is some 20 km lower than it previously was, the perigee is about 5 km higher (i.e., the current orbit is more circular than previous orbits). It's ground repeat interval is 4 days.

USA 186 is the secondary West plane satellite in the KH-11 constellation. The hunt is now on for USA 245, the primary West plane KH-11. Recovery of the primary East plane KH-11, USA 224, will have to wait untill early summer.

When I observed it yesterday it was bright (mag +1.5) and briefly flared to mag 0 near 19:32:50 UT (March 15, 2017).

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