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Thursday, February 28, 2013


Comet 2011 L4 PanSTARRS tonight (28 February, 2013)

Comet C/2011 L4 PanSTARRS imaged from 20:45 ACDST at Largs Bay, Adelaide. This is a stack of 5 images each 4 seconds long at 400 ASA, 3 x zoom taken with my Canon IXUS. Images stacked in The GIMP. Comet is at the top, Fomalhaut middle left (click to embiggen, you will need to to see the comet)Single image (4 second exposure, 400 ASA, 3 x zoom, 20:45 ACDST), with the comet and Fomalhaut indicated, the comets tail can just be seen.
Singel frame taken at 9:08 ACDST (400 ASA, 15 seconds, 3 x zoom). Tail more obvious now, click to embiggen)Animation of 18 frames taken at minute intervals rom 20:50 ACDST. 400 ASA, 3 x zoom but exposure increases from 4 seconds to 15 seconds during the shoot. Click to embiggen.

After days of cloud I finally had a nother chance to see comet C/2011 L4 PanSTARRS. The sky was clear and I headed down the beach at 20:30 ACST. Using Fomalhaut as my reference (just visible low above the horizon in the twilight glow) I swept my binoculars to the right and up and almost immediately saw the pale comet in the twilight. It was much clearer than my first glimpse.

The comet had a nice, star like head and a short but clear fan shaped tail.

I started shooting images with the camera around 20:45 ACDST, starting with a 4 second exposure, and increasing as the twilight deepened. Around 21:00 I could just see the comet with the unaided eye as a faint star, no tail (before I could just detect it with averted vision). In binoculars the tail looked to be roughly 1 degree long. It was hard to be accurate with the relatively bright sky.

I couldn't estimate the brightness of the comet more than roughly, there were no decent nearby stars for comparison, all I can say was it seemed to be brighter than Magnitude 4 (and was brighter than the nearest star, which was magnitude 4.4). I'd hazard the prospects for it being at least magnitude 2 and reasonably visible to the unaided eye by March 5 are very good.

The comet was visible all the way to the horizon, although by around  21:15 it was visibly dimming in the horizon murk.

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