The 2007 Comet 17/P Holmes Super Outburst
as recorded by John O’Neal and other members of
Day 1, October 24th, 2007
October 24th arrived like
any other fall day here in
On October 24th, however, all that changed. It started with a rather inconspicuous post buried amongst a few other hundred I 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
Dear Ramon, After seeing your e-mail, I looked for 17P/Holmes and found what appears to be a yellowish, 7.1 magnitude star at the comet's position. With averted vision I may have seen a faint coma or maybe not. Moonlight made itdifficult to be certain. Is this "star" actually 17P? Does this fit with your observation? If so, this is a remarkable object. I used a 25cm reflector at 76x and 214x on Oct. 24, 4:10 UT.
Now, things were really
looking up. Not only was there a comet out there visible in my scopes,
was observed from the continental US !
“Hey, if Bob
During the day while I was waiting for nightfall, the following email came through. This was the icing on the cake. Confirmation that the comet really was as stated:
Hello Ramon and all, yes, the outburst is real, and we congratulate wuth Juan Antonio Henríquez Santana and our spanish collegues for the discovery of this extremely interesting phenomena. Right now we are performing some follow-up of the outburst remotely from RAS-NM. Here is a preview: the proper motion of the comet is evident, as well as its extreme brightness (severe blooming on 60 sec image through a 25nm reflecotr + CCD):http://tinyurl.com/ywgy7g
this later...Kind regards,Giovanni Sostero
and Ernesto Guido (AFAM, CARA)Wed, 24 Oct 2007
I was happy as a bug in a rug. “It doesn’t get much better than this”, I remember thinking.
Wrong! The next email knocked my socks off………….
Hello Giovanni and all, The
comet is now naked eye at mag.
4.0! Here are my observations over the past 10 hours: After hearing of
Naves' observation last night on comet-images, I looked at 17P/Holmes
25cm reflector at 76x and 214x on Oct. 24,
The comet was a mag. 7.1 "star" with a
yellow hue. This morning (Oct. 24, 11:15UT), the moon was out of the
sky and seeing was
excellent. To my amazement, 17P had brightened to naked eye visibility
nearly equal to 48 Per at visual mag.
4.0. In the same telescope, the coma showed an intense, nearly stellar
nucleus about 2.5"-3" across set in a small, 10" diameter, much
fainter, fuzzy disklike coma. The nucleus
distinctly yellow. The comet's appearance was very reminiscent of McNaught last winter when seen in the daytime
sky. What a
sight! Bob King,
Magnitude? Now, it’s a
object. Naked eye, even, from a dark site.
changes everything. Could it be true?
confirmed the unbelievable super outburst of 17P/Holmes beside
Yes, it’s true. Now, if it
will just stay clear until I get home from work after Midnight so I can
comet. Before leaving for work I sent out the following email to let my
amateur at the Black /river Astronomical Society know what was
Group, Well, the race
is on. Over the last 24 hours Comet 17/P Holmes has gone from an object
couldn't see in our telescopes to a daytime viewing comet. Magnitude
from, like right now, in
I did some quick searches on the web and learned a little about this comet..............
In 1892, the comet underwent a
similar outburst to the one that is occurring today. According to The Cosmic Mirror, over 100 years ago, when
its earlier brightening, it stayed brilliant for more than a week,
visible to the unaided eye for three weeks. The size of the comet's
appeared to increase. Then, a couple months later, a second outburst
in Holmes. It is unknown if the comet's sudden brightening will follow
previous event, but keep your eye on it to find out!
Immediately upon learning of the comet I fired an email message off to fellow comet hunter, Dave G. He responded back in kind almost immediately with the following chart of the comet’s path through Perseus.
I also got this email from
Larry back pretty quickly:
I've been so lost in work
it was pure joy to get this type of news. Think you could also include
clear sky nights, John?Thanks
for the alert. Larry J. Wed, 24 Oct 2007 13:23:15 -0400 (EDT) firstname.lastname@example.org
Larry responded back rather
quickly as did Dave Gulyas and Dave Lengyel. I’m glad they posted
because I still hadn’t found time to do any serious searches for
Folks, I'm hoping this works.I'm sending you a .pdf file for tonight's position of comet 17P/ Holmes in Perseus. It has brightened, according to reports, by 14 magnitudes! That's about 400000 times increase in brightness. That being said, let's hope we get some clearing. Dave Wed, 24 Oct 2007 14:43:20 -0400David Lengyel email@example.com
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:
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, 2007
Finally, I got home from work.
By then it was Thursday morning of the 25th. I couldn't wait to see
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
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
Here’s what the comet looked like in binoculars. Everybody was right. It looked sort of like a planet, very bright and quite large as compared to the stars around it. (Below left.)
And the telescopic view was breathtaking. (Above right.) The Comet was about the size of Mars in the scope, bright yellow and had a very slight fuzzy outer perimeter.
I got a few hours sleep and
awoke the following afternoon to find the excitement still
Dear colleagues,17P/Holmes 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 Yoshida email@example.com
As of 17:00
And the Emails were firing around our club member’s, as well….
at a loss for words. Astronomically
that's only happened to me one other time -The Shoemaker-Levy 9 impact
Jupiter. This is one odd duck! I just finished viewing it for about 5
through 12x50 binocs as the clouds rolled
truly is unusual to say the least. I'll be checking for sucker holes
the evening because I want to see what a scope might show. Larry Thu,
2007 19:52:17 -0400
I concur as well !!! 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 trusty 10x50s and my old Jeagers 4inch F5.
The view was awesome at all magnifications. Jack Reising Thu, 25 Oct 2007 18:04:17 -0700 (PDT)
John R firstname.lastname@example.org
Just spotted Comet Holmes: 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 trusty 10x50s and my old Jeagers 4inch F5. The view was awesome at all magnifications.
Jack Reising Thu, 25 Oct 2007 18:07:31 -0700 (PDT)John R email@example.com
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
Found it tonight, full moon, 7:45 p.m., with 10X50 handheld binocs, then brought out the tripod-mounted 20X80s. Astonishing sight. Clouds rolled in, but later cleared nicely, and there it is. This thing is especially stunning in stereo-vision with 20X magnification. An ethereal globe illuminated from the center. Wow. --Bill Ruth Thu, 25 Oct 2007 22:18:49 -0400William Ruth William.A.Ruth@oberlin.edu
Group, Here's my
(elementary?) comet photo of the amazing comet Holmes. Wow, this is
strange comet. Brightening by a million times? Dave, Thu, 25 Oct
David Lengyel firstname.lastname@example.org
To All, Somehow, someway, TWO CONSECUTIVE NIGHTS of comet observations have been done from
Oct 26.05 UT: m1 = 2.2, Dia = 3', DC = 8 ...NE...Phillip J. Creed(
view in 25x100s,
though, was the show-stopper. Folks, I really,really don't know how to describe this!
In 20+ years
as a comet observers, it's not the most
comet I've seen, but it's certainly the most surreal.
The coma was about 3' in diameter. The yellow color that was soprominent last night also seems a bit muted. The color tonight was more of a cream color. The coma was noticeably-elongated in a N-S direction, with a pseudo-nucleus of ~20" in diameter noticeablydisplaced south of the coma's center. There was no diffusivity to the outer coma at all; it was a very sharp demarcation between background sky and coma. Think a bright planetary nebula on steroids, and you're close.
The coma itself was not
uniform in brightness. There appeared to be a brighter patch lying E
and W of
the nucleus. There was a dimmersection,
mostly in the
northeastern quadrant (spanning about PA 345 through true north to PA
was about 2/3 of the way out from the nucleus. It looked almost like
coma on the NE quadrant had partially "peeled" away, leaving an arc
of "shadow" from PA 0 to 90.]
Clear Skies, Phil Fri, 26 Oct 2007 03:39:41 -0000Phil email@example.com
The night of the 26th,
(actually, the morning of the 26th) arrived and found Dave
shooting from his observatory and I from mine and we were comparing
latest news we had received was that the comet’s magnitude had reached
~ 2.7 mag. We
were doing comparisons to
other stars nearby and determined that the magnitude was much closer to
2.7. Dave sent out an email mentioning this. Later estimates agreed
observations. Here’s a copy of Dave’s message…
sure what to
say...??? The clouds look to have rolled in for good now (01:50EDT) but
01:00EDT the comet seemed to have brightened even further. Was on the
with John O. at the time and he concurred. Have allot
of images, no time to sort through right now, bed is calling. I'll post
images tomorrow. WOW!!! Dave G. Fri, 26 Oct 2007 02:06:49 -0400Dave
The overall appearance was totally different. The comet no longer resembled an out of focus star. While the overall AVARAGE brightness had dimmed, the central core or nucleus had brightened and the outer dimmer section had expanded nearly twofold. For lack of a better reference people started referring to the comet as a nebulous, almost planetary looking object.
And the core seemed to be playing little tricks on us, depending where you were observing from, or perhaps what time you made your observations. In the photo below you can clearly see a dark ring around the core of the comet. This was reported by many observers. I was only one of many to get this shot.
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.
Friday afternoon I awoke to even more news…………
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#msg6902
or by clicking on the ASO News on the website homepage. Dr. Clay
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 would look like.
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.
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 29th through November 3rd. 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.
Here’s a shot from N0vember 30th.
As you can see the blue, outer coma is quite large and brightening.
Note that all photos in this article were shot by the author unless otherwise noted.
By November 3rd. you can see the outer coma is continuing to brighten and grow.
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 our
On November 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.
Here’s a shot I took through my Meade 80mm f/5.0 through my 30D @ prime focus.
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.