The 2007 Comet 17/P  Holmes Super Outburst

Day 1, October 24th, 2007

October 24th arrived like any other fall day here in northern Ohio. It was about 50 degrees outside and clear. Night-time temperatures were beginning to drop into the high 30's and low 40's. Many of the leaves had fallen by now and those that remained were vividly displaying their post chloroformic hues.  The Moon was full and overhead most of the night so I didn't have plans for shooting when I got home from working the 3-11pm shift. Since I was working 3-11pm shift I awoke about noonish and proceeded to check my email. I was aware that Comet Holmes was out there. I’ve been watching the photos posted by the guys with astrographs and sbig cameras. At 17.5 magnitude, however, Comet Holmes was not even near the top of my priority list of things to check out.

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 HenrÝquez Santana (MPC J51) reports a outburst of Comet 17P/Holmes. Observations during the night of 2007 October 23/24 show that the comet is some 7 magnitudes brighter. The outburst has been confirmed by Gustavo Muler (MPC J47) and Ramon Naves & Montse CampÓs (MPC 213).Wed, 24 Oct 2007 02:34:25 -0000

Now, I’ve heard of Messiers  Santana and Muler and know of their good reputations. “This could be serious.” I remember thinking. And hour and a half later the following mail came through. 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. Thank you, Bob King, Duluth, Minn. USA

Now, things were really looking up. Not only was there a comet out there visible in my scopes, but it was observed from the continental US ! “Hey, if Bob from Duluth can see it, so can I!” 

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 HenrÝquez 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):  More on this later...Kind regards,Giovanni Sostero and Ernesto Guido (AFAM, CARA)Wed, 24 Oct 2007 13:36:37 +0200

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 Ramon Naves' observation last night on comet-images, I looked at 17P/Holmes with a 25cm reflector at 76x and 214x on Oct. 24, 4:10 UT. 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 being nearly equal to 48 Per at visual mag. 4.0. In the same telescope, the coma showed an intense, nearly stellar false nucleus about 2.5"-3" across set in a small, 10" diameter, much fainter, fuzzy disklike coma. The nucleus was distinctly yellow. The comet's appearance was very reminiscent of McNaught last winter when seen in the daytime sky. What a sight! Bob King, Duluth, Minn. USA, Wed, 24 Oct 2007 07:06:44 –0500

4th Magnitude? Now, it’s a binocular object. Naked eye, even, from a dark site. This changes everything. Could it be true?  Dear colleagues, I confirmed the unbelievable super outburst of 17P/Holmes beside Tsurumi River in Yokohama City, Kanagawa, Japan! It is visible with naked eyes in a large city! Wed, 24 Oct 2007 22:43:24 +0900 (JST)

Yes, it’s true. Now, if it will just stay clear until I get home from work after Midnight so I can see the comet. Before leaving for work I sent out the following email to let my fellow amateur at the Black /river Astronomical Society know what was transpiring:  Hi, Group, Well, the race is on. Over the last 24 hours Comet 17/P Holmes has gone from an object most of couldn't see in our telescopes to a daytime viewing comet. Magnitude estimates from, like right now, in Japan, are coming in at 2nd  magnitude and still brightening. It's interesting that this comet did exactly the same thing in past apparitions. The good news for us is that this comet is still 2.5 au out in favorable skies for us northerners. Look in Perseus which is rising in the east at dusk for a yellow stellar looking object. Dave G. just sent this finder aid that will prove quite useful. Enjoy,Astronomically, John

I did some quick searches on the web and learned a little about this comet..............

History of Comet 17P/Holmes

The comet was discovered by Edwin Holmes on November 6, 1892 whilst conducting regular observations of the Andromeda Galaxy (M31). It was confirmed by Edward Walter Maunder (Royal Observatory, Greenwich, England), William Henry Maw (England), and Kidd (Bramley, England). The comet was independently discovered by Thomas David Anderson (Edinburgh, Scotland) on November 8 and by John Ewen Davidson (Mackay, Queensland, Australia) on November 9 (who had previously, on 19 July 1889, discovered C/1889 O1, the first comet discovery from Queensland). The first elliptical orbits were independently calculated by Heinrich Kreutz and George Mary Searle. Additional orbits eventually established the perihelion date as June 13 and the orbital period as 6.9 years. These calculations proved that this comet was not a return of 3D/Biela. The 1899 and 1906 appearances were observed, but the comet was lost after 1906 until recovered on July 16, 1964 by Elizabeth Roemer (US Naval Observatory, Flagstaff, Arizona, USA) aided by computer predictions by Brian G. Marsden, the comet has been observed on every return since.
Source: Wikopedia 

More History of Comet 17P/Holmes

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 the comet had its earlier brightening, it stayed brilliant for more than a week, remaining visible to the unaided eye for three weeks. The size of the comet's coma appeared to increase. Then, a couple months later, a second outburst occurred in Holmes. It is unknown if the comet's sudden brightening will follow this 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 a few clear sky nights, John?Thanks for the alert. Larry J. Wed, 24 Oct 2007 13:23:15 -0400 (EDT)
Larry responded back rather quickly as did Dave Gulyas and Dave Lengyel. I’m glad they posted finder charts because I still hadn’t found time to do any serious searches for information.  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

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. It may clear later tonight. Dave Wed, 24 Oct 2007 14:57:14 -0400David Lengyel  Comet 17P/Holmes is apparently undergoing a spectacular brightening.Information and links at: <> 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 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

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 escalating: 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  As of 17:00 UT Seiichi Yoshida (Japan) reports it has brightened to magnitude 2.8! See for the latest and a finder chart. Greg Crinklaw

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.

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 trusty 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)

John: 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 R Thu, 25 Oct 2007 18:07:31 -0700 (PDT)

 John, when I looked at your photos I first thought you uncharacteristically missed the mark by a bit. Now 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 circular coma!  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 R Thu, 25 Oct 2007 22:18:49 -0400

To All, Somehow, someway, TWO CONSECUTIVE NIGHTS of comet observations have been done from Northeast Ohio, aka the 6th Circle of Astronomical Hades. (Not the worst spot, but you guys get the idea...) Anyhow, the transparency was very good, and the view was most rewarding: Oct 26.05 UT: m1 = 2.2, Dia = 3', DC = 8 ...NE...Phillip J. C (North Canton, OH) [With the naked-eye, it was just ever-so-slightly fuzzy, unlike last night where it looked distinctly stellar. The 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 impressive comet I've seen, but it's certainly the most surreal. The coma was about 3' in diameter. The yellow color that was so prominent 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 noticeably displaced 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 90) that was about 2/3 of the way out from the nucleus. It looked almost like the outer 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 -0000

The night of the 26th, (actually, the morning of the 26th) arrived and found Dave G. shooting from his observatory and I from mine and we were comparing notes. The 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 than 2.7. Dave sent out an email mentioning this. Later estimates agreed with our observations. Here’s a copy of Dave’s message… I'm not sure what to say...??? The clouds look to have rolled in for good now (01:50EDT) but about 01:00EDT the comet seemed to have brightened even further. Was on the phone 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 some images tomorrow. WOW!!! Dave G. Fri, 26 Oct 2007 02:06:49 -0400

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.  

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 CCD direct measure), and is easily naked eye at magnitude 1.9 visual (10 x 50 binoculars); this 5-second RGB composite was taken with the 0.4m SCT f/3 via CCD at 09:55 U.T. and the field measures 6 x 6 arc minutes. The nucleus was measured photometrically at m1=11.8, offset significantly from center; also note the very bright opposing (from the nucleus) scintillating condensation equally offset from center, but in the opposite direction. Note that on Oct. 25, similar measures of the coma revealed diameter of approximately 121 arc minutes. The latest image, and a same scale comparison to that of October 25, is found at the link: by clicking on the ASO News on the website homepage. Dr. ClayArkansas Sky Observatories, Harvard MPC/ H43 (Conway) Harvard MPC/ H41 (Petit Jean Mountain) Harvard MPC/ H45 (Petit Jean Mtn. South) Sat, 27 Oct 2007 06:00:19 -0500P. Clay Sherrod

 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.


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

  Oct24 CometHolmesOct25  Oct26 Oct27 Oct29    Oct30    Oct31 

November 2nd through November 6th .

 November 2nd        November 3November 4November 5     November 6 

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.

November 16th

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 Ż terabyte drive. I curse our beloved northern Ohio weather every cloudy night, because I don’t want to miss that next big event that Comet Holmes has in store for us.

Note that all photos in this article were shot by the author unless otherwise noted.

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 Cincinatti, Ohio. We loaded up the small scope and headed for the Louisville Astronomical Society’s site in Evansville, Indiana. We have a standing invitation to visit through our club member, Randy B.

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.