28 October 2007

Comet 17P/Holmes (28 Oct. 2007 UT)

Date: 28 October 2007
Time: 2:08 - 2:17 UT
Telescope: 130mm Refractor
Magnification: 111x
Seeing: Good
NELM: 5.0 (Bright Moon)
Temperature: +39 F (+4 C)

The above sketch shows Comet 17P/Holmes. South is up, and west is to the right in this mirror-reversed view. The bright, stellar pseudo-nucleus was easily visible on this night using the 5.1 inch refractor. As in previous sketches, some bright cometary material is visible on the southwest side (the side opposite the Sun) of the pseudo-nucleus. Also noted was a brighter ring near the outer edge of the comet's outer coma. This ring appeared
to be somewhat less bright to the southwest, perhaps due to the sunlight having to pass through the rest of the comet's coma in order to provide illumination.

No color was noticed at 111x; but at significantly lower magnifications the comet appeared to have a subtle, yellowish tint. The view is aesthetically more pleasing at lower magnifications; but higher magnifications (such as 111x) make it easier to see some of the details.

Comet Holmes remains very bright in the night sky and is visible to the unaided eye as a slightly fuzzy star. Even the slightest optical aid (such as a small pair of binoculars) is sufficient to reveal the non-stellar nature of this interesting comet.


apollo said...

What a lovely drawing Bill! I know from personal experience that drawing at the eyepiece takes a tremendous amount of skill, and it's great to see the art still alive and well in the CCD age.

Your observations of slight colour at lower magnifications and variation in density with respect to the suns direction are very interesting - something that I think only seasoned observers would spot. Keep up the good work :)



Roberto Lugo said...

I do not remember another comet like, I do not see its tail, and it is huge, I think his direction is toward here, what you think about my theory?

Bill Greer said...

Hi Roberto,
Comet Holmes has been known about since the 19th century. It's currently moving further from the sun while moving only slightly closer to earth.

This comet's rapid increase in size is the result of a sudden outburst of activity and the associated expansion of the comet's coma.