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

[Sterling K. Webb]

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.
>
>
> ______________________________________________
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
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>
>


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