Monday, March 9, 2009

Curious coma-tail of C/2007 Q3 (Siding-Spring)

Recently we imaged C/2007 Q3 (Siding Spring), remotely with a "Skylive" scope from Grove Creek (Australia):

details on picture.

Through image processing, the comet show a funny effect: at low contrast, an asymmetric coma is seen, about 45 arcsec in diameter, with an obvious elongation toward (about) East (PA 90 deg). In high contrast, a broad tail, nearly 80 arcsec long, became obvious; but it points toward South-West, at about PA 230 deg (i.e., in nearly opposite direction)!

Further image processing, capable to extract possible inner coma features (azimuthal median subtraction, 1/r theoretical coma subtraction) confirms the presence of an asymmetric coma, with a possible feature exing toward East, North-East, developing in a counterclockwise direction.

Preliminary photometric analysis of our frames, show a total m1 magnitude of about 13, while the sharp central condensation shine at m2 about magnitude 15 (unfiltered CCD).

Comet C/2007 NQ3 (Siding-Spring) moves along a parabolic orbit, whose perihelion will be reached in October 2009, at 2.2. AU from the Sun.

Updated orbital elements and ephemerids are available in the Minor Planet Center's Website:

by Giovanni Sostero, Ernesto Guido & Paul Camilleri

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