Comet and Meteor Circular
-------- Original Message --------
Subject: Comet and Meteor Circular 2007 No.3
Date: Mon, 5 Nov 2007 21:47:23 +0200
From: Tim Cooper
Comet 17P Holmes
By now many of you have heard of the 14 magnitude outburst of comet 17P Holmes. Typical of the unpredictability of comets this event had to occur while I was travelling on business in Europe, and where the weather did not permit me to see it anyway. It is currently about as far north as it gets, but you might want to hunt it down anyway. Comet Holmes was predicted to become no brighter than magnitude 16, but it appears to have experienced a large outburst on October 23, nearly six months after its perihelion passage in early May. The reasons for the outburst are still unknown at the moment. The comet also underwent an outburst in 1892 (the discovery year) to magnitude 4, fading to magnitude 7 within a week.
The moon favours observation in the coming week, but unless you are far north, the comet will be low on the horizon at best. It culminates presently just before 01h00 at an altitude of only 13 degrees at Johannesburg, and located to the right of alpha Persei. Use binoculars to find the comet. On November 10 it culminates at 00h30, at the same altitude, and November 15 at midnight, located just over 1 degree from alpha Persei. The comet is only 18' from the star on November 20, but the bright 70% moon will interfere. The latest observation from Mike Begbie, now resident in England, has the comet at magnitude 2.2, highly condensed, and with no tail.
Peter Jenniskens predicts the earth should encounter the dust trail left behind by comet 55P Tempel-Tuttle in 1932 around November 18 at 23h00 UT (01h00 on the morning of November 19 for us). The peak should result in ZHR around 30-60/hour, be of short duration, with above average brightness meteors. However the radiant will be very low, only rising shortly after 1 am, and rates from South Africa will be very low at best. However it will probably worth watching in the event the shower offers any long pathed earth grazing fireballs, which will no doubt live long in the memory.
Observations were received from Michael Poll, Dudley Field, Wayne Mitchell and Koos van Zyl. Based on global reports enhanced rates occurred again in 2007, with a peak centred on October 22 at 11h00 UT (daylight in South Africa) with ZHR=45/hour. My thanks to these four observers.