16 November 2007

Observing Location	MO
Observational Period	2100-2230 EST
Atmospheric Conditions	Cloud Cover Clear Temperature 38°F Wind Light Breeze Humidity Moderate Feels Like Wind Chill 32°F It was better out tonight than they had been predicting when I decided to forgo a trip into Manhattan for public observing at Columbia University. There were some passing light clouds that interrupted my observations a couple of times. There might have been a light haze that was being lit up by α Per. Transparency Good Seeing II
Instruments	Golden Gate 7x35 binocular - Charlie SAR: Coulter CT-100 Newtonian reflector - Charlie Celestron Omni 20mm (21x) Celestron Omni 2x Barlow
Observing Party	Charlie Ridgway

Target 17P/Holmes Constellation Per Category Comet Time yyyymmdd.hhmm 20071116.2100 EST 2007 Nov 17.08 UT Comments Comet 17P/Holmes is approaching Mirfak, α Per. Cartes du Ciel graphic Tonight they are only 37' apart and by my last assessment the comet was over 23' in diameter. In the detail below the red circle around the comet shows its size to the farthest extent that I can detect it with SAR. Since people have been reporting to ICQ that they are seeing the comet as a 2nd magnitude object I targeted brighter stars and switched to the In-Out technique in hopes of making a better brightness estimation. But it was to no avail. I advanced the brightness of the comet marginally to Mag. 2.88 but other people are reporting to ICQ over the past two days that it is dimming and is now in the neighborhood of Mag. 3.12. It is ironic that when I finally get the comet to 2nd magnitude everyone else has downgraded it to 3rd magnitude. Cartes du Ciel graphic Star Mag. Descrioption α Aur 0.08 Brighter β Ori 0.18 Brighter α Ori 0.45 Brighter α Tau 0.87 Brighter γ Ori 1.64 Brighter β Tau 1.65 Brighter ε Ori 1.69 Brighter ζ Ori 1.74 Brighter α Per 1.79 Brighter &Alpha Aur; 1.90 Brighter α UMi 1.97 Brighter α Ari 2.01 Brighter β UMi 2.07 Brighter α And 2.07 Brighter α And 2.07 Brighter κ Ori 2.07 Brighter β Per 2.09 Brighter γ And 2.10 Brighter γ Cas 2.15 Brighter α Cas 2.24 Brighter δ Ori 2.25 Brighter β Cas 2.28 Brighter β Peg 2.44 Dimmerer α Cet 2.54 brighter β Peg 2.54 Brighter β Ari 2.64 Brighter θ Aur 2.65 Brighter δ Cas 2.66 Brighter ι Aur 2.69 Brighter γ Per 2.83 Brighter ζ Per 2.84 η Tau 2.85 Brighter 17P/Holmes ~2.90   ε Per 2.90 Equal γ Per 2.91 Dimmer ζ Tau 2.97 Dimmer β Tri 3.00 Brighter δ Per 3.01 Dimmer ε Aur 3.03 Dimmer η Aur 3.18 Dimmer ρ Per 3.22 Dimmer ε Cas 3.35 Dimmer η Ori 3.35 Dimmer λ Ori 3.39 Dimmer λ Tau 3.41 Dimmer α Tri 3.42 Dimmer η Cas 3.46 Dinner γ Cet 3.47 Dimmer 27 Tau 3.62 Dimmer ε Cas 3.65 Dimmer ζ Cas 3.69 Brighter ζ Aur 3.69 Dimmer ζ Tau 3.72 Dimmer α Psc 3.82 Dimmer 20 Tau 3.87 Dimmer γ Ari 3.88 Dimmer γ Tri 4.03 Dimmer δ Cet 4.08 Dimmer 23 Tau 4.14 Dimmer 19 Tau 4.30 Dimmer 17P/Holmes looked huge tonight. Comparing it to the star field there seemed to be a nebulosity all the way from α Per out to near HIP 16394 which is a distance of 63’. I think that I am seeing glare from α Per. I know there was a ray of light coming off α Per straight up through the comet. I felt that the comet filled the space between HIP 16196 and TYC 3320-02439-1 (barely visible under the edge of the coma), 36’53”. This is bigger than I have ever assessed it before but within the range reported to ICQ.    Power FoV Count Diameter 21.6x 2.3° 3 ° 43.2x ~1°   Average   I broke one of my rules tonight and never even took the Barlow out of my bag. Tonight would have been a good night to see if transparency and the brightness would have supported it. I took a closer look at the text data from ICQ. Instrument Users Naked-eye too many to count Scope 10 Scope with CCD 3 7x50 binocular 9 10x50 binocular 7 7x35 binocular 4 25x100 binocular 3 20x80 binocular 2 11x80 binocular 10x80 binocular 20x50 binocular 8x30 binocular 9x13 binocular 1 each 3x40 monocular 1 4x20 monocular 1 Of the 198 diameter estimates 88 were made using optics 110 were made naked eye Of the 11 diameter reports with 0.1’ accuracy 2 were made with a CCD 3 were made with a scope 1 was made with a binocular 5 were made naked-eye Future Appulses of Note 19Nov07 18’ away from α Per 22Jan08 10’ away from β Per 6Mar08 half way between ε Per and ξ Per 3May08 7’ away from M38