October 24th arrived like any other fall day here in northern
On October 24th, however, all that
started with a rather inconspicuous post buried amongst a few other
received that day. It read as follows:
Juan Antonio Henríquez
Santana (MPC J51) reports a
outburst of Comet 17P/Holmes. Observations during the night of 2007
23/24 show that the comet is some 7 magnitudes brighter. The outburst
confirmed by Gustavo Muler (MPC J47) and
& Montse Campàs
213).Wed, 24 Oct 2007 02:34:25 -0000
During the day while I was
waiting for nightfall, the following email came through. This was the
the cake. Confirmation that the comet really was as stated: Hello
Ramon and all, yes,
the outburst is real, and we congratulate wuth
Antonio Henríquez Santana and our spanish collegues for the
discovery of this extremely interesting phenomena. Right now we are
some follow-up of the outburst remotely from RAS-NM. Here is a preview:
proper motion of the comet is evident, as well as its extreme
(severe blooming on 60 sec image through a 25nm reflecotr
this later...Kind regards,Giovanni Sostero
and Ernesto Guido (AFAM, CARA)Wed, 24 Oct 2007
Magnitude? Now, it’s a
object. Naked eye, even, from a dark site.
changes everything. Could it be true? Dear
confirmed the unbelievable super outburst of 17P/Holmes beside
I did some quick searches on the web and learned a little about this comet..............
By afternoon the news was getting out and spanning the globe like wildfire. My PDA was humming like an angry little bee all day at work. Images started coming from the dark parts of the globe while information and research began coming from light parts. This was a long day for me, wondering if it would still be clear when I got home after midnight. Here’s a few short excerpts of news I received that afternoon: Folks, OK, Spaceweather has now update their site with the comet info. It probably will be more useful than my map. http://www.spaceweather.com/ It may clear later tonight. Dave Wed, 24 Oct 2007 14:57:14 -0400David Lengyel email@example.com Comet 17P/Holmes is apparently undergoing a spectacular brightening.Information and links at: <http://www.spaceweather.com/> This object is amazing! I have just observed it with an 8-inch f/10 Cassegrain, boosting the power up to 163X then to 508X...the bright inner coma seems displaced offcenter toward p.a. 315 degrees. The inner coma opens up into a fan toward p.a. 300, and I have noticed one ripple, akin to the hoods/ripples seen in Hale-Bopp ten years ago. The coma is uniform in brightness, aside from this fan-shape material eminating from the central condensation, and has a well-defined edge. I measured the coma to be 69.3" diameter using the drift method. The entire object has a nice yellow-white color, no sign of any tail. The apparent magnitude is +2.8 (estimated using Mirfak at +1.9 and the other two bright stars adjacent to it at +3.0 each) and has remained rather steady all evening (first estimate at 1:15UT, Oct. 25, first observation with a 4.5" f/8 reflector shortly after). It seemed to be a bit brighter compared to the 3.0 mag. star arount 3:00UT (estimated = +2.7) but was +2.8 at 5:15UT. I plan to keep a close eye on this object as we expect to have clear skies for the next 7 days... Wed, 24 Oct 2007 23:05:15
Day 2-3, October 25th & 26, 2007Finally, I got home from work. By then it was Thursday morning of the 25th. I couldn't wait to see this comet I had heard so much about during the day.............And, so, of course, it was cloudy. Oh, No!!! This is not possible..... Here’s my email from the following afternoon: Hello, Group, I got home last night @ 12:30am. Sat in my little pod until 2:30am watching clouds whizz by. Suddenly a clear spot develoved in front of the moon and I quickly aligned my goto using the moon, then focused my 30D at prime focus of the Orion 120mm f/5.0. Then I entered the coordinates of the comet and it dutifully slewed to the desired location. Another 45 minutes passed before a sucker hole finally opened up over Perseus. I was watching with binoculars and found the comet immediately recognizable. It was at least 2nd mag, BRIGHT yellow and HUGE! Imagine Mars being yellow. That's what the comet looks like in binoculars.I quickly rushed to the scope and looked inside. There it was. The apparent diameter was even more impressive in a scope. With an added bonus: In the scope you could see a thin outer layer of fuzziness. What a sight. This is a must see comet & do it quickly. There's a lot of speculation out there over whether this current brightening will last, or perhaps it's the comets death toll Only time will tell......Astronomically, John Thu, 25 Oct 2007 13:06:08 -0400John W. O'Neal, II firstname.lastname@example.org
I got a few hours sleep and
awoke the following afternoon to find the excitement still
got brighter furthermore! Perseus does not look
"Perseus" familiar to us due to the bright stellar object now.Thu, 25 Oct 2007 02:34:17 +0900 (JST)Seiichi
As of 17:00
Larry :I concur !!! The darn thing is naked eye at a full moon! At
least 2nd mag!! Very
yellow in color with a very
distinct coma & nucleus. I just finished viewing it with my
10x50s and my old Jeagers 4inch F5.The view was awesome at all magnifications. Jack R
Thu, 25 Oct 2007 18:04:17 -0700 (PDT)
And the Emails were firing around our club member’s, as well…. I'm at a loss for words. Astronomically that's only happened to me one other time -The Shoemaker-Levy 9 impact with Jupiter. This is one odd duck! I just finished viewing it for about 5 minutes through 12x50 binocs as the clouds rolled in. It truly is unusual to say the least. I'll be checking for sucker holes through the evening because I want to see what a scope might show. Larry J. Thu, 25 Oct 2007 19:52:17 -0400.
when I looked at your
photos I first thought you uncharacteristically missed the mark by a
that I've viewed it through a scope I can see the photo's are pretty
dead on. I
kept wanting to focus and/or clean non existant dew off the lens. Almost perfectly
Larry J Thu, 25 Oct 2007 21:35:00 -0400
To All, Somehow,
TWO CONSECUTIVE NIGHTS of comet observations have been done from
Others captured a fan shaped core, off center cores, cores that looked like they were jetting material in different directions, etc. A few photos even sported tails. These were the super fast systems, with serious enhancements, of course.
Day 4, October 27th, 2007
Friday afternoon I awoke to
even more news…………Even
more incredible each
night; the comet 17P (Holmes) now measures 255 arc minutes across (via
direct measure), and is easily naked eye at magnitude 1.9 visual (10 x
binoculars); this 5-second RGB composite was taken with the 0.4m SCT
CCD at 09:55 U.T. and the field measures 6 x 6 arc minutes. The nucleus
measured photometrically at m1=11.8,
significantly from center; also note the very bright opposing (from the
nucleus) scintillating condensation equally offset from center, but in
opposite direction. Note that on Oct. 25, similar measures of the coma
diameter of approximately 121 arc minutes. The latest image, and a same
comparison to that of October 25, is found at the link: http://www.arksky.org/smf/index.php?topic=1429.msg6902#msg690or by clicking on the ASO News on the website homepage. Dr. ClayArkansas Sky
MPC/ H43 (
Arriving home Friday night (Saturday morning) the outlook was grim. The Oberlin Clear Sky Clock showed no signs of clearing but I was firm in my belief that it would clear. I opened up my observatory and waited. At about 2:30am a small hole appeared and I was able to focus on the moon and setup my goto.
The goto proved to be invaluable on these nights, by the way. Shooting through holes in clouds doesn’t give one much time to starhop around. By the time you see a bright star and start to slew toward it, it’s gone. Hoping to recognize that star without the benefit of surrounding stars, by which to form a reference is next to impossible. But with a goto, all that is unimportant. Simply set to scope to the desired coordinates and wait for a hole. When the hole appears, shoot. It’s really that simple. (On a side note, I have learned to estimate the lengths of exposures I can take by watching the size of the hole and the speed it’s moving at.) The average sucker hole in the clouds was about 20 degrees across and moving at such a speed as to allow 8 seconds of cloud free exposures. Since 8 seconds is where I chose to shoot, I merely had to watch the size of the next hole.
In this shot you can see the almost fan shaped off center nucleus some folks described.
Here’s a shot through the 80mm
f/5.0, taken just to see what a wide shot with stars in the background
Around this time people were starting to report a bluish colored, large outer extended coma around the comet.
In this photo taken on the morning of the 29th, you can begin to see the outer coma.
Over the next few nights the outer coma became brighter and brighter and eventually formed an extended tail that many observers enlikened to an octopus or calamari.
Here are my shots from the clear nights between the nights of October 24th through October 29th. Unfortunately it was cloudy here on the two nights that the tail was visible, so we missed out on that event in the comet’s history. This sequence was shot through an Orion EON ED80. 500mm @ f/6.25
October 22nd through October 29th
November 2nd through November 6th .
By November 16th, 2007 the comets was over 2 degrees in diameter and so large, I could no longer shoot it through my telescopes. Here's an image shot with the Canon 40D and a 300mm lens.
I didn’t take a lot of images like this because I had to grieviously overexpose the comet in order to see the outer coma. I prefer the shorter exposures that showed details in the inner coma.
By November 1st, the comet had undergone quite a metamorphosis. We, as amateur astronomers are accustomed to measuring changes to the sky in weekly, monthly, yearly and even decade long timeframes. For example, we anxiously await the minima of Algol next week, or the new moon next month, or the big meteor shower next year, or even the eclipse of a lifetime in 2025. An entire industry has sprung up to keep us informed of what’s coming up and when and where it’s coming up. There’s a plethora of magazines, calendars, publications and internet resources available to keep us informed of the parade of nightly events in our sky.
But, nothing like this has ever happened before. Sure, there have been lots of comets before, but none that have ever maintained the excitement level of Comet Holmes. Most comets have a pretty predictable life, you must admit. They appear, move toward the sun, brighten, move away from the sun, dim and return to oblivion. Sure they may sprout a tail and give us some really spectacular views, but none have ever come even remotely close to putting on a show like Holmes.
It’s a bit overwhelming when an event takes place in the sky that dramatically changes overnight, every night. In the first week the comet went from 17.5 magnitude to 1.8 mag. If that wasn’t enough it went from just a few arcseconds in diameter to a few whopping degrees in apparent diameter. Every single night out with comet Holmes was like a night out with a totally new comet. One night it had a jet, next night it had two nuclei, then it had a tail, then the tail disconnected, then the diameter doubled, etc, etc.
I was having a rough time
staying awake at work. I found myself spending every dark, clear moment
possible in my observatory. I’ve shot thousands of photos and have have many, many
gigabytes of files
and am close to filling my external ½ terabyte drive. I curse
Note that all photos in this article were shot by the author unless otherwise noted.
18th the comet was going to cross
over Mirfac in Perseus. I really wanted to
see this event, but
weather predictions indicated it would be cloudy across the entirety of
Northern America on a line north of
This was a difficult image to take. Mirfac is a 2nd magnitude star that requires a very short exposure time. The comet is much dimmer and requires a much longer exposure time. I shot lots of exposures at different exposure times to find the one image that would show both at their best. This is one of my favorite memories of Comet Holmes.
This image is much more straightforward. I shot 45 30 second exposures and then stacked them to get this image. It’s my second favorite, to date.
Then I took an old photo of the Moon shot with the same scope and copied it into the image. You can see the comet’s outer diameter is equivalent to the moon’s apparent diameter as viewed here from Earth
Here are two of my favorite photos from the first two weeks of the Great Outburst of Comet 17/P Holmes. The first is a composite of each night’s images as compared to the moon. The furthest left image was taken on October 5th and the last on November 5th.
Second is a collection of 30 second exposures taken from a fixed unguided tripod and stitched together using a software program called Startrails.
On November 18 Dave Gulyas shot a couple of absolutely stunning wide angle shots. First shows the comet, M34, M45, Mirfac and the Mellot 20 asterism.
Second, Dave shot the Comet, the Double Cluster and M31. Both images were quite well done and devoid of the problems that usually plague these types of wide angle shots. Great job, Dave!
On December 26th, 2007 the skies finally cleared and allowed me get a shot of Comet Holmes along with Comet Tuttle in the same field of view.