The Amazing Comet Holmes (17P) – the outburst of October 2007

This periodic Comet has stunned the Astronomy world by going from a very dim 17^th Magnitude to a bright naked-eye object in less than 24 hours. The first reports of the comet’s explosive brightening started hitting the internet on October 23, 2007 from the dark side of the Earth – Europe and Asia. By the evening of October 25^th 2007, when it finally cleared in the Binghamton, NY area, the Comet appeared as a star-like object in the Eastern evening sky. Strangely, it looked nothing like a classic comet with long tail. Rather it looked like a new yellow star in the Constellation of Perseus.

History

The comet was discovered by Edwin Holmes on November 6, 1892 whilst conducting regular observations of the Andromeda Galaxy (M31). The normally quite dim comet had undergone a similar outburst as what is happening in October 2007. This is a short period comet that revolves around the sun approximately every 6 years. It never gets that close to the sun, and is usually only visible in a large telescope. The nature of its occasional outbursts unknown.

Observing Reports – from the Kopernik Observatory and Members of the Kopernik Astronomical Society(KAS)

7:30 pm EDT, Oct 25, 2007 – submitted by George Normandin, KAS

Observation made with Celestron 20x80 Deluxe binoculars & 7x50 binoculars from a rural location in the Town of Maine.

Conditions: Full moon, clear sky.

Easy to see naked-eye under full moonlight. Not quite as bright as Mirfak (Alpha Persei) or Delta Persei, but just as prominent in the moonlight. Noticeable yellow color. Perhaps a hint of fuzziness. The Comet is near Mirfak and about the same altitude as the moon.

In 7x50 binoculars the comet is a yellowish little fuzzball, with no other structure visible.

In 20x80 binoculars the comet shows a bright but fuzzy inner coma, and a gradually diming outer coma, both with an obvious yellow color. The outer coma is slightly extended in a western direction. Total size: Inner coma about 30 arc seconds, outer coma at least 5 arc minutes.

Evening, Oct 25, 2007 – submitted by Nick Guydash, KAS

I observed through both 8x56 binoculars and my 3.5" Questar telescope (prime focus at 1600 EFL).  I agree it was a tad dimmer than Mirfak but easily visible to the naked eye.  My binos showed a slightly asymmetrical fuzz ball.  I thought the view though the Questar at 40x was amazing.  It showed a distinct central bright spot that suddenly dropped off in brightness to form a dimmer "ring" that was much larger than the bright center.  The outer "ring" was definitely asymmetrical away from the sun.  Maybe with time it will show a more distinct tail.  I thought I could glimpse some detail in the outer coma - perhaps what looked like a "dark lane" concentric to the outer edge.

8:00 pm EDT, Oct 25, 2007 – submitted by Art Cacciola, KAS

I first observed Comet 17P/Holmes naked eye with my daughter around 8 PM.  It was easily visible, looking like a new planet.  Later I put it in my ETX-90 and saw much more detail.  I did not see the jets or the formation of a tail, but the moon was pretty bright.  I could see the golden yellowish center and greenish outer envelope.