Monday, February 18, 2008

Comet C/2008 C1 (CHEN-GAO) Update

Comet C/2008 C1 (Chen-Gao) is currently crossing the rich Milky Way fields within Cassiopeia, not far from the 2.nd magnitude star Gamma Cas. This create some troubles performing its photometry & astrometry follow-up, due to the annoying stellar crowding that usually "pollutes" the cometary coma.

On 2008, Feb. 16.7, we obtained the "cometary first light" on a new scope, a MEADE LX200R 14" OTA, mounted on a 10Micron GM2000 QCI robotic mount (this will be the heart of our remote-controlled set-up, located in the new astronomical observatory atop Mount Matajur, currently under completion):

Selecting a frame series relatively free from background stars, we did some follow-up about this comet. We found that the coma extends nearly 1 arcmin, with a relatively sharp central condensation (m2 almost 15.5). Total (unfiltered) magnitude is equal to 12.5. The Afrho parameter (proxy of the dust abundance within the coma) is ~150 +/- 25 cm, with a typical pattern:

(for more info's about the Afrho parameter importance, and and the role of amateur astronomers in its determination, please visit the CARA's webpage)

There are signs of a tiny tail extending toward North-East:

This detail moves according the proper motion of the comet:

so it's unlikely to be an artefact.

Giovanni Sostero & Ernesto Guido

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