17P/Holmes 10-28-07

17P/Holmes
Periodic Comet
Parks Astrolight EQ6 • 6" f/6 Newtonian Reflector
7.5mm Parks Gold Series Plössl • 120x, 26' Field of View
28 October 2007 • 05:55-06:45 UT

Here is my second observation of the outburst of periodic comet 17P/Holmes. It is still easily visible to the unaided eye, but seems to have dimmed slightly. Its size has increased considerably and is now clearly non-stellar, appearing as a small circular puff of nebulosity in both the 6x30 finder and the 10x50 binoculars.

The envelope of dust surrounding Comet 17P/Holmes has expanded considerably in the 44 hours since my previous observation of this spectacular outburst. I estimate its apparent angular diameter as about 8', nearly double the size seen in the previous sketch. Though much larger, the comet also seems slightly dimmer; the strong yellow color has also abated somewhat and the hue is now very pale.

The pseudo-nucleus remains a stellar point, even at high magnifications, but it now seems to have become increasing shrouded by the dust that has been emitted. A bright fan of material extends in a roughly southward direction from the pseudo-nucleus to the perimeter of the still almost perfectly circular coma. Faint streamers curve northeastward on either side of this fan like the appendages of a ghostly scarab. A semicircle of darkness wraps halfway around the core on the northeast side.

Near the pseudo-nucleus, two prominent but diffuse streamers dominate the bright fan of ejected dust, one extending due south, and the other south-southwest. A prominent knot is visible intermittently in the SSW streamer, very close to the pseudo-nucleus.