[meteorite-list] Holmes [17P], continued

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Thu, 25 Oct 2007 21:26:52 -0700 (MST)
Message-ID: <2106.71.226.60.25.1193372812.squirrel_at_timber.lpl.arizona.edu>

Hi Sterling:

It looks more like a planetary nebula to me! I will try to get an estimate
of its size tomorrow night when I am at a darker site in Yuma with a
bigger scope and maybe a camera.

It is always hard to get a real magnitude for a comet since one usually
talks about integrated magnitude. However, I would say that it is not that
different than Mirfak in Perseus which is 1.8, so much brighter than last
night. This makes sense since it a lot bigger too.

On Thu, October 25, 2007 9:01 pm, Sterling K. Webb wrote:
> Hi, Larry, List,
>
>
> Stuck under cloud cover so dense that even the
> nearly Full Moon does not even make a bright area behind it, I have only
> your description and my imagination to work with, but your observation
> could be of what is in effect an "inner" and an "outer" coma with
> different densities.
>
> The reflectivity of the coma is dependent on the
> density of the particles making up the coma. The usually even brightening
> of the coma toward a "star-like" condensation (the nucleus) is due to the
> continuously increasing density of particles as you proceed toward the
> nucleus, and that uniformity is the result of a more or less constant rate
> of outflow.
>
> The appearance of a brighter (hence denser) inner
> coma could be the density discontinuity or boundary between the spreading
> and dispersing coma of the original outburst and the expanding "front" of
> a new and greater outburst of an increased amount of material that has
> occurred more recently and is now expanding outward.
>
> Wouldn't that be great? I put in my request for a
> magnitude 0 or magnitude -1 comet by Saturday night! Let's have a bigger,
> better comet (and one that will last longer than my clouds).
>
> Larry, if you know the field of view of your scope,
> you can estimate the size of the coma. Every arc minute at the distance of
> Holmes 17P is 70,680 km across (or
> 424,000 km per degree).
>
>
> Is it bright? Brian Marsden says he's getting nova reports:
> "This is a terrific outburst," said Brian Marsden, director
> emeritus of the Minor Planet Center, which tracks known comets and
> asteroids. "And since it doesn't have a tail right now, some observers
> have confused it with a nova. We've had at least two reports of a new
> star."
>
> Go, Holmes!
>
>
>
> Sterling K. Webb
> ---------------------------------------------------------------------
> ----- Original Message -----
> From: <lebofsky at lpl.arizona.edu>
> To: "Mark Langenfeld" <mlangen at execpc.com>
> Cc: "Meteorite List" <meteorite-list at meteoritecentral.com>
> Sent: Thursday, October 25, 2007 10:02 PM
> Subject: Re: [meteorite-list] Holmes [17P], continued
>
>
>
> Hi Again:
>
>
> We just looked at it with a 100mm f/5 telescope and it is clearly orange.
>
>
> However, it is also very obvious that this thing is "unusual." I thought
> that I had a focusing problem, but the scope was in focus.
>
> There is a beautiful circular coma, but the "condensation" is NOT
> star-like. It is about 1/4 the diameter of the outer coma! Never seen
> anything like this.
>
> Larry
>
>
> On Thu, October 25, 2007 7:29 pm, Mark Langenfeld wrote:
>
>> Even with the extra-bright full moon and the usual urban light
>> pollution, 17/P Holmes is a nice naked-eye object here in Madison, WI
>> this evening. The coma is suprisingly large and shows a bright,
>> star-like condensation or center through 7X50 binoculars. I agree with
>> Jeff that
>> color is apparent, showing a yellowish --almost orange -- cast.
>>
>> If you haven't yet taken a look (and have clear skies), NOW is the time
>> to get outdoors and witness this most unusual event.
>>
>> Mark
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "Jerry" <grf2 at verizon.net>
>> To: "Meteorite List" <meteorite-list at meteoritecentral.com>
>> Sent: Thursday, October 25, 2007 8:01 PM
>> Subject: [meteorite-list] Holmes [17P]
>>
>>
>>
>>
>>> Just to update those interested, there is no diminishing in
>>> brightness in fact there may be a slight increase. It defintely looks
>>> cometary in binoculars with a bright center and hazy coma. And as
>>> someone said last nite, it has a redish cast.
>>
>>
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>>
>>
>
>
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Received on Fri 26 Oct 2007 12:26:52 AM PDT