[meteorite-list] MORE COMET HOLMES #3

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 26 Oct 2007 01:00:13 -0500
Message-ID: <030401c81795$7a16a710$b92ee146_at_ATARIENGINE>

Hi,

6.7 arc minute is 469,000 km at 17P's distance.
13-17 arc minutes is 910,000 to 1,190,000 km.
The first brightening was observed at Tennerife
just after local midnight, October 24, or about
52-54 hours ago. If the "bright" coma radius is
now 235,000 km, it's been expanding at roughly
4500 km/hour and the extended coma at 10,000
km/hour. Another 24 hours (Friday night) would
add 216,000 km to the "bright" coma diameter, or
685,000 km (9.7 arc minutes). This is about 1/3
of the size of the Full Moon (which is 30 arc
minutes). A second 24 hours of expansion would
take the bright coma up nearly half the size of the
Full Moon. (Of course, the expansion is not necessarily
linear, but it may in fact expand faster than the linear...
for a while.)

Another of tonight's observations posted at the Sky and
Telescope site: From S&T's Alan MacRobert: "Omigod.
thin clouds lit by the full Moon I had to guess where
Perseus was, but I swept around with 10x50 binoculars,
and wham, there was the comet! It's sure not starlike now,
at least not in the 10x binocs with homemade image
stabilization. It's a very sizeable bright fuzz spot, perfectly
round, with a large, brilliant, hazy nucleus and a very sharp
edge to the circular coma. Golden yellow with just a
hint of green. When the clouds finally cleared and I
could see it with the naked eye, it was still starlike to
my vision. Magnitude 2.6 or 2.7." (Apparently you can
just barely see the green, with big enough binoculars.
Carbon monoxide like Hyutake?)

IF (big if) this is a mega-outburst and the brightening lasts
until Sunday, Monday, Tuesday, we will have 1, 2 , and 3
hours of dark sky with the comet in the sky at the beginning
of night before the Moon rises (varies with lattitude). My
local Weather Prophets say clear here by Saturday --- keep
going, Holmesie! May you get big and bright enough that
ordinary people look up and say, "What The H*** is
THAT Thing?"


Sterling K. Webb
----------------------------------------------------------------------------
----- Original Message -----
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Friday, October 26, 2007 12:12 AM
Subject: Re: [meteorite-list] MORE COMET HOLMES #2


I've updated the profile at
http://www.cloudbait.com/gallery/comet/holmes.html with data taken
tonight. The brighter central coma is now at least twice as wide (6.7
arcmin across), with some structure showing as far out as 13-17 arcmin.

I did take some images tonight which I may add to the site tomorrow. I
still see no structure, just a bigger object. Right now I'm running an
overnight photometric sequence, so I'll see tomorrow how the brightness
might be changing with time (that will actually be a light curve; the
other data is an intensity profile).

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Thursday, October 25, 2007 10:40 PM
Subject: [meteorite-list] MORE COMET HOLMES #2


> According to Chris, the coma is about 3.3 arc minutes across,
> or 230,000 kilometers. The very brightest part is about 2.8 arc
> minutes or 196,000 km across. Chris has a light curve on his
> website (URL below.
>
> Sterling K. Webb

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Received on Fri 26 Oct 2007 02:00:13 AM PDT