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Comet 17P/Holmes, November 2007

Images taken at UCLO

This image of Comet 17P/Holmes was taken at about midnight GMT on the night of 28/29th October 2007, with the Celestron 14-inch telescope and STL-6303E CCD camera.

North is up and East is to the left. The image is a composite of several images taken through red, green and blue filters, each about 30 seconds exposure. The star images are slightly trailed due to the time difference of a few minutes between the RGB exposures.

The cometary nucleus is the bright condensation in the upper part of the central coma of dust and gas; the other bright points are background stars. The whole diffuse coma is several arcminutes across, and is noticeably expanding in size from night to night.

The comet's tremendous increase in size over the next month can be seen in the composite image below.

The images were taken with a Canon A80 digital camera with TC-DC52A Tele-converter and 3x Zoom. Image processing was done with The GIMP 2.2 and Georg Hennig's Astro Plugins, stack registration with Christian Buil's IRIS 5.51 under Linux ( Kubuntu 6.06 LTS with Wine).

Image information:
  29 Oct 2007: added stack of 5 images (6s, ISO 50, f/4.9),
  01 Nov 2007: merged stack of 3 images (6s, ISO 400, f/4.9),
  13 Nov 2007: merged stack of 3 images (6s, ISO 400, f/4.9),
  23 Nov 2007: merged stack of 4 images (5s, ISO 50, f/4.9),
  29 Nov 2007: merged stack of 7 images (5s, ISO 200, f/4.9).

Discovery by Edwin Holmes in 1892

The following article was taken from "The Observatory", December 1892, No.195, pp.441:

Discovery of a New Comet in Andromeda

We have had very little decent weather for observing in London of late, but I make a practice of never missing an opportunity.

Sunday, November 6th, was far from clear, and did not improve as the night deepened, so that after looking at Jupiter and a few double stars and finding the seeing unsatisfactory, I made up my mind to close observing at 11.30 P.M.

Ever since the temporary star appeared in M 31, I have taken an observation of that nebula at every chance I have had in case any further outbreak took place, and on Sunday night it occured to me to try whether I could see the small comes to μ Andromedæ under such conditions. On swinging the telescope round from β I caught something nebulous in finder and mistook it for M 31. Going to the eyepiece of reflector I recognized at once that it was not the nebula and called out involuntarily, “What is the matter? there is something strange here.” My wife heard me and thought something had happened to the instrument, and came to see. I recognized at once that it was a new comet, but before I could get more than a rough position clouds hid it. I said to my wife: “This is coming end on, and will be a big fellow, and I must get a position before I leave it if possible.” I wrote at once to Mr. Maunder, Mr. Maw and Mr. Kidd, of Bramley, and posted, and then got clearer sky, and with Slade micrometer made it immediately preceding Σ 72, the interval of passing the centre being 1m 10s at a single trial.

Having only restricted sky room, I was unable to make a second measure or see if motion was perceptible. I measured the diameter of the nebulosity as exactly five of the one minute divisions of the micrometer. As these are calculated for a 6-feet focus, and my focus is 78½ inches, the estimated diameter is rather over than under the mark, but I consider the milky state of the sky somewhat reduced apparent diameter, and that probably 5' is exact. The position in declination is very close also, as both comet and star travelled accurately on wire. As regards R.A., the difference did not exceed 1m 10s I am sure, but it may have been 1s less.

On Monday morning I wrote the Astronomer Royal, but as I omitted to say I saw the Andromeda Nebula at the same time, he very naturally at first thought I had blundered. My friend Mr. Kidd, with whom I have corresponded for years, and to whom I am indebted for much counsel and kindness, also suspected a mistake, but on Monday evening he saw the comet with the naked eye, as did also Mr. Bartlett of Bramley. I wrote again to Greenwich, and being now satisfied of the reality of the discovery, they took measures to spread necessary information. Mr. Maw accepted the matter at once and wrote to congratulate me.

It is unnecessary for me to enter into any particulars of further observations because they are sure to be furnished by those with better and more exact appliances, at any rate as regards position; but perhaps my impressions of change, when seen a second time on November 14th, at 10.45, may have some value, because no one but myself and Mrs. Holmes appears to have seen it for some days after its first appearance with any telescopic means. On the 14th the nucleus was much less distinct and much less bright, the boundary of the nebulosity was much less well defined and less perfectly circular and far more like a nebula. The intrinsic brilliancy was less, but the diameter largely increased. Only getting a look at it betwixt clouds and showers, I was not able to measure, but by comparison with the half-field of Slade micrometer I estimated the diameter at from 8' to 9'.

It will be a pleasure to learn that others have had better weather than myself, and gathered a large number of facts for our instruction.


The article is published with permission from the editors of The Observatory.

The temporary star in M31 mentioned by Edwin Holmes was probably the Supernova in M31 in August 1885 (S Andromedæ or SN 1885A).

The article is available in various formats via ADS and can be retrieved as PDF file here.