Telescope Reviews: ALERT - Comet 17/P Holmes in mega outburst

I have observed the comet several times since last Thursday night October 25th but this is the first opportunity I have had to write up and post my observations. During my observations on October 25th there were a number of clouds around as well as the light from the full Moon but I was able to get a good view of the comet using the TMB 175mm f/8 apo refractor on it's homemade Dobsonian-style mount. Through the telescope at 47x and 70x the pseudo-nucleus was visible with fan-shaped material coming off from it. An inner coma and larger but fainter outer coma was visible as well. The outer coma had a gauze-like appearance to it. Both the inner and outer coma was light yellow in color. There were times where there appeared to be a fainter envelope or halo around the outer coma. To help enhance the detail I tried some different filters that I use when observing deep-sky objects including a Lumicon OIII filter and Baader UHC-S filter. During my two hour observing session I made a couple of sketches of the comet.

On Saturday night October 27th I observed the comet again before the clouds rolled in this time with a TMB 105mm f/6.2. Even with the smaller aperture the comet appeared larger and the inner coma, pseudo-nucleus, and outer coma appeared light yellow.

The sky was clear Sunday night/Monday morning October 28th-29th so I observed the comet with the TMB 175mm for several hours and made a couple of sketches. The comet appeared noticeably larger through this telescope than when I observed it last Thursday. Also, while the color of the pseudo-nucleus and inner coma still appeared light yellow, the outer coma appeared green at low power and blue-green at higher power. In addition at low power the outside edge of the outer coma did appear to have somewhat of an annular look to it but this was not as noticeable at higher power. The outer coma showed some variation in tone. There were two stars visible in the outer coma. By comparison the pseudo-nucleus appeared more diffuse.

I was curious if I could see more clearly the fainter envelope or halo around the outer coma that I noticed last Thursday night. The envelope or halo on the right hand side of the coma had a smooth round appearance to it and reminded me of a parabolic hood. I was able to trace it as it arced around the top and bottom of the comet. However as I studied the halo as it came around the bottom of the coma and up towards the left-hand side it no longer appeared smooth and round. Rather my eye kept detecting what looked like striations of lighter material coming off of the outer coma.

To make sure this wasn't an optical illusion I spent a long period of time trying different magnifications and filters, as well as techniques I use to enhance subtle detail in deep-sky objects. This included taking long deep, slow breaths to increase the oxygen level to the brain, gently tapping the telescope tube, and moving the comet outside of the field of view and letting in drift back in while determining when there was a change in the sky background. After a while I was able to determine that some of these striations of lighter material were coming off of the bottom left hand side of the outer coma at an angle, as well as straight back from the coma. There were some of these striations of lighter material coming off on the upper right hand side but they were not at the same angle or as prominent. It appears this lighter striations were the beginning of a tail. Around the same time I was detecting these lighter striations that appeared to be beginning of a tail two other observers obtained photographs of the tail showing similar detail. I would urge all observers to look for the tail(s) as it grows more pronounced.

Clear Skies,

Eric Jamison
http://members.leapmail.net/~ericj/