Kurt and I rendezvoused at Little Mountain at about 5:00 am and were greeted by a star-spangled sky, with the exception of some ragged cloud strands to the south that were slowly drifting northeast, right over the target zone (of course). They never totally obscured the area, but it got a bit fuzzy for a while. Venus was dazzlingly brilliant- Kurt pointed-out a glare reflection off of ground ice that was startlingly bright. Kurt was using his binos, I had my 15x70mm binos and the 4.25" f/5 Dob, with 20mm Erfle ep for 27X and a reasonably wide field. I had mounted the Mars-eye finder earlier yesterday and was eager to try it out on the scope. Nice reflex sight, I found myself using the green dot at a low intensity. The thin, transient cloud cover and low elevation (atmospheric extinction) made star identification difficult, and even after we were sure the comet was above the horizon it wasn't apparent. Then at almost the same instant, we realized we were looking in the wrong place, and swung over to the correct position, where the comet was instantly seen. I estimated a coma size of about 3 arc minutes, I think I remember Kurt giving it another minute or two. My eyes had began to water by then and protracted views were getting difficult. It was dimmer than I had expected, but once located, an obvious object. The impression in the little Dob was similar to a small spherical galaxy seen in a larger instrument. This comet is nothing spectacular and is only going to get dimmer in coming days, albeit higher at the start of twilight. But I'm glad I went up there, the sky was spectacular, Jupiter was amazing in the small scope. Even though the light pollution has taken a toll on the Little Mountain site, it still holds up remarkably well for being so close to SLC. The skies to the east are still the best, fortunately for morning comet watchers. The temperature wasn't too bad thanks to the warm spell we are currently enjoying- it was much colder when I was up there shooting Hale-Bopp in '97. A Sunday morning well-spent. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
--- Chuck Hards <chuckhards@yahoo.com> wrote: Chuck, thanks for encouraging me to show up. Based on my pre-charting, I probably would have blown it off till March 7. My observing note write-up follows. Unlike your note, in my Siskell and Ebert rating scale - I give it a "thumbs up" instead of "thumbs neutral." Must be the result of comet deprivation since Machholz in December 2004. -:) - Kurt ======================= Comet Pojmanski (C/2006 A1) Ob Report In December 2004, observers were treated to the flyby of C/2004 Q2 (Comet Machholz), a tailess maximum mag. v4.1, comet with a high inclination (~34 degs). Mag v5.1 Comet C/2006 A1 (Comet Pomjanski) is (for northern hemisphere observers) a new apparition much like comet Machholz - only this time with the promise of a tail: Photos (with tail) by John Drummond, Possum Observatory, New Zealand http://www.possumobservatory.co.nz/comet_2006a1_pojmanski.htm - Southern hemisphere track charts (going north) through March 2,2006 from the Comet Section of the Royal Astronomical Society of New Zealand: - http://www.rasnz.org.nz/Comets/C2006A1.htm#Chart2 I believe that we are currently seeing Comet Pojmanski on its inbound turn. The JPL-MPC Ephemeris shows C/2006 A1 holding at its current brightness (estimated at v6.5) through March 7 at which point it will begin its dimming phase. Harvard-MPC Ephemeris and plotting input file - http://cfa-www.harvard.edu/iau/Ephemerides/Comets/2006A1.html JPL-MPC Ephemeris generator - for generating local topocentric ephemerides - http://ssd.jpl.nasa.gov/cgi-bin/eph Southern observers have been watching this comet - that is moving at 93 degs inclination to the ecliptic - for some time. They report its 5-6 arcminute diameter brightening from v7.5 on 1/30/2006 to v5.4 on Feb. 26. See reports at ICQ-MPC Recent Comet Magnitudes webpage http://cfa-www.harvard.edu/iau/icq/CometMags.html Comet Pojmanski is coming into view for north latitude observers but at an time that makes observing this bright comet a challenge for 40N observers. The comet rises between 12:15 UTC - 12:30 UTC (5:15am-5:30am local time) at 41N, low in the south east horizon at az 120, alt 0. Rough 41N courtesy charts generated from Cartes du Ciel through March 7, 2006. 90 deg Eq chart http://members.csolutions.net/fisherka/astronote/finder/Comet2001A6_90degEqu... 90 deg Alt az chart http://members.csolutions.net/fisherka/astronote/finder/Comet2001A6_90degalt... 30 deg Alt az chart http://members.csolutions.net/fisherka/astronote/finder/Comet2001A6_30degalt... Sky and Telescope Online Article with chart http://skyandtelescope.com/observing/objects/comets/article_1684_1.asp But astonomical twilight ends abruptly between 12:35 and 12:45 UTC (5:35-5:45 local time). To further complicate the picture, Venus is currently about 7-8 degrees away and has an extraordinary brillance of v-4.8. Venus is bright enough to cast shadows and creates a 5-8 deg light wash-out zone around its position. Comet Pojmanski is travelling past alf Cap tonight (2/27/2006) and towards Aquila. But Venus is also travelling towards alf Cap through March 7. The problem of astronomical twilight and the small observing window is illustrated by the following rising table for my op: *********************************************** Date__(UT)__HR:MN Azi_(a-appr)_Elev T-mag *********************************************** 2006-Feb-25 12:15 111.9655 -2.4042 6.52 2006-Feb-25 12:30 r 114.3784 0.2290 6.52 2006-Feb-25 12:45 A 116.8454 2.8126 6.52 2006-Feb-25 13:00 Am 119.3758 5.3406 6.52 2006-Feb-25 13:15 Nm 121.9783 7.8064 6.52 2006-Feb-25 13:30 Nm 124.6616 10.2033 6.52 2006-Feb-25 13:45 Cm 127.4341 12.5235 6.52 2006-Feb-25 14:00 Cm 130.3040 14.7591 6.52 *********************************************** My own experience is that by 12:45 UTC (5:45 am) the comet was whited out and not visible. Finally, this comet is low on the horizon and rises out of the atmospheric zone. A consequence of these motions for 41N observers - and the first key to seeing Comet Pojmanski - is that there is a very narrow observing window beginning at 5:15 that lasts about 15 minutes. The following is a table of rising tables for my op at 41N through March 7. If you arrive at 5:20 to begin observing - you'll miss the comet in end of astonomical twilight. The key is to arrive and set up by 5:00 am local time and begin tracking the rise of alf Cap before the comet rises. The following is a table of altitude times at 12:15 UTC (5:15am) for Comet C/2006 A1 through March 7 for my op: *********************************************************************** Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC Azi_(a-appr)_Elev T-mag *********************************************************************** 2006-Feb-26 12:15 20 18 00.35 -15 36 17.1 110.4982 -0.3053 6.52 2006-Feb-27 12:15 20 19 50.41 -13 02 27.6 108.9579 1.8074 6.53 2006-Feb-28 12:15 20 21 53.47 -10 25 22.7 107.3458 3.9236 6.54 2006-Mar-01 12:15 20 24 09.21 -07 45 44.3 105.6642 6.0323 6.56 2006-Mar-02 12:15 20 26 37.28 -05 04 18.3 103.9162 8.1218 6.59 2006-Mar-03 12:15 20 29 17.26 -02 21 53.2 102.1059 10.1803 6.63 2006-Mar-04 12:15 20 32 08.67 +00 20 41.0 100.2386 12.1957 6.68 2006-Mar-05 12:15 20 35 11.01 +03 02 34.5 98.3204 14.1566 6.74 2006-Mar-06 12:15 20 38 23.74 +05 42 58.7 96.3583 16.0524 6.80 2006-Mar-07 12:15 20 41 46.30 +08 21 08.0 94.3600 17.8736 6.87 2006-Mar-08 12:15 20 45 18.12 +10 56 20.4 92.3338 19.6121 6.95 2006-Mar-09 12:15 20 48 58.62 +13 27 58.5 90.2884 21.2613 7.03 2006-Mar-10 12:15 20 52 47.22 +15 55 30.2 88.2329 22.8165 7.11 2006-Mar-11 12:15 Am 20 56 43.34 +18 18 29.2 86.1761 24.2746 7.21 ***********************************************************************
From the proceeding table, note that the comet becomes progressively twilight limited as we proceed into March - although you can see it by arriving earlier.
The second key to seeing Comet Pojmanski is a good ephemeris table showing rising times at your observing point. Make a geographic specific epheremis for your observing point before you leave. Show up early enough to be tracking on the horizon as the comet rises. The Moon is favorably positioned below the horizon at 12:15 UTC through March 10 at which point Moonlight washout will begin to be a problem. On Feb. 26, 2006 at 12:30-12:45 (UTC), fellow observer Chuck Hards and I watched this comet rise on the south eastern horizon near bet Cap from our op at Little Mtn, Utah (approx. 41 N, 111.8 W). First, we tracked alf Cap's rise off the horizon, and then a few minutes later, bet Cap. From our mountain horizon blocked op, Comet Pojmanski finally rose at approx~ 12:15 UTC (5:25am) and was high enough to be observable by 12:30 UTC (5:30am local time). C/2006 A1 is very similar in appearance to last year's Comet Machholz and is strikingly beautiful. Because of light-wash out from Venus, it was difficult to estimate the diameter or magnitude of the comet. Even so, the comet was distinct and bright - a promise for things to come on future mornings. The nucleus has a DC5 concentration and its bright nucleus 3' arcsize was easily compared to the 3' arcsize of nearby double bet Cap. ( DC=5 Still more condensed; the central condensation strongly influences m1, hampering the use of the In-out method. ) The size of the outer coma and magnitude was foregone due to the sky wash-out from nearby Venus. However, the outer coma appeared to give a total comet size have a total comet size of about 5-6' - similar to reports by southern hemisphere observers. Sky wash-out from Venus also prevented seeing the comet's tail other than as a suspected averted vision detection close to the nucleus. I expect the tail will become more visible as Comet Pojmanski pulls away from Venus and gains more altitude. Although currently there is only a narrow observing window of 15-20mins, subjective time, it seemed like we watched for 30 minutes. This was more than enough to enjoy the show. The observing window should improve through March 7, by which there may be close to an hour to watch the comet before astronomical twilight ends. Weather is a factor in northern latitudes at this time of year. But if you have a weather window, I strongly recommend making an early morning sojourn to take a long at this new bright comet. Do not be deterred by its low altitude near the extinction zone. It is worth the trip. - Canopus56(Kurt) P.S. to lurkers - A) If someone would post a 3-D orbit plot, I would appreciate it. B) Does anyone have any biographical background on Prof. Pojmanski. I understand he has been active in the comet area for a number of years. C) Comets recharge the debris from which meteor showers are created. My rough visual impression is that the Earth is orbiting towards the crossing track of the comet. Considering Comet C/2006 A1's orbit, any opinions on whether there may be any chances for an increased meteor shower later in the year? __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
P.S. to lurkers - A) If someone would post a 3-D orbit plot, I would appreciate it. C) Comets recharge the debris from which meteor showers are created. My rough visual impression is that the Earth is orbiting towards the crossing track of the comet. Considering Comet C/2006 A1's orbit, any opinions on whether there may be any chances for an increased meteor shower later in the year? Kurt: Here is a link to a java applet for this comet's orbit. It's on the asteroid side of the wall within JPL and they seem to have better tools over their than on the comet side of the wall. http://neo.jpl.nasa.gov/cgi-bin/db?sstr=2006a1 As for meteor activity, I should think that the high inclination will keep any debris well away from earth orbit, even though the perihelion distance is inside the orbit of Venus. DT __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
--- daniel turner <outwest112@yahoo.com> wrote:
Kurt: Here is a link to a java applet for this comet's orbit. It's on the asteroid side of the wall within JPL and they seem to have better tools over their than on the comet side of the wall. http://neo.jpl.nasa.gov/cgi-bin/db?sstr=2006a1
As for meteor activity, I should think that the high inclination will keep any debris well away from earth orbit, even though the perihelion distance is inside the orbit of Venus. DT
Thanks Daniel, that's what I was looking for. Clearly the track moves within Venus's orbit and does not intersect Earth's track. The orrey view really matches up with night sky - the comet is currently crossing the ecliptic, Venus, the comet and the Sun are in the same order as seen on the celestial sphere. - Kurt __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
participants (3)
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Canopus56 -
Chuck Hards -
daniel turner