StefanR Posted: Wed Oct 31, 2007 3:51 am Post subject: Reply with quote This l ong-slit spectrum covers about 2/3 of the visible spectrum. The slit made a spatial slice across the coma, nicking the nucleus. The dark absorption bands are primarily the solar Fraunhofer lines from reflected sunlight (in the blue these can also be seen in the skyglow away from the comet). The bright bands are generated by ionized gas seen extending beyond the inner dust-dominated region.
The most prominent bandhead in the green is due to the C2 molecule, as is the fainter bandhead in the blue. Other emission features in the green and yellow are due to more C2 and NH2.
Quote: I can say this comet is just extra amazing. This is very big, bright and beautiful. I found and captured image easily with much light pollution, in Tehran city. I captured these image with Canon EOS 20D, EQ6 mount and Meade 8" Telescope and edited with Photoshop CS2, also I took nebula-broadband filter for better resolution. You can see this comet with the naked-eye when the great moon in the sky.
Ilia Teimouri, Tajrish,Tehran,Iran Oct. 25, 2007
Posted: Wed Oct 31, 2007 4:32 am Post subject: Reply with quote http://www.skyandtelescope.com/observin ... 75326.html Quote: The Outburst. The first person to notice something happening this time, according to IAU Circular 8886 (issued October 24th by the Central Bureau for Astronomical Telegrams) was A. Henriquez Santana at Tenerife, Canary Islands, shortly after midnight on the morning of the 24th local time. The comet was then about 8th magnitude, but within minutes Ramon Naves and colleagues in Barcelona, Spain, caught it at magnitude 7.3.
Quote: Then things only got better. As Earth continued to turn, nightfall arrived in Japan. "It is visible with naked eyes in a large city!" posted Seiichi Yoshida, who observed the comet from beside Tsurumi River in Yokohama. By 17:15 Universal Time he was describing Comet Holmes as magnitude 2.8.
Quote: "This object is amazing!" posted Brian Cudnik of Houston, Texas, on the Yahoo CometChasing group after coming in from his telescope on the evening of the 24th. "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 off-center toward position angle 315°. The inner coma opens up into a fan toward position angle 300°, and I have noticed one ripple, akin to the hoods/ripples seen in Comet Hale-Bopp ten years ago. The coma is uniform in brightness, aside from this fan-shape material emanating from the central condensation, and has a well-defined edge." He measured the coma to be 69 arcseconds wide using 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 Alpha Per at +1.9 and the other two bright stars adjacent to it at +3.0 each) and has remained rather steady all evening."
Quote: Monday, Oct. 29: Last night the comet was very plainly a little disk to the naked eye rather than a star. Definitely a more interesting naked-eye view now! No change in brightness in the last 24 hours. In fact, the average of all good magnitude estimates has basically stayed flat since the outburst. (Light curve.)
Quote: Last night the bright coma was more than 8.3 arcminutes wide, according to a measurement by Clay Sherrod. Its diameter has been growing roughly 1.5 arcminutes per day. At Paris Observatory, F. Colas and J. Lecacheux that the bright coma has been expanding at a constant rate of 575 meters per second from the nucleus.
Note faint, wide tail toward lower right On the night of October 28–29, Sean Walker took a deep exposure that shows hints of a wide tail (to the lower right here). He used a 108mm f/4 Faworski Astrograph for 63 minutes of exposures with an ST-10XE CCD camera. Click image for larger view. S&T: Sean Walker And is Comet Holmes starting to grow a tail? Several visual observers and imagers report the subtlest traces of one. For instance, at right is a deep image by S&T's Sean Walker on Sunday night. http://media.skyandtelescope.com/images ... 29_800.jpg
StefanR
Re: Recovered: Holmes gets very bright
Ion01 Posted: Wed Oct 31, 2007 1:29 pm Post subject: Reply with quote After reading the TPOD I believe I am beginning to understand why its discharging at such a far distance. Quote: Comets spend most of their time far from the sun where the charge density is low. Because comets move slowly, their electric charges reach equilibrium with the weak, radial solar field. As they get closer to the sun, however, their nuclei speed into regions of increasing charge density and varying electrical flux. Their polarity and charge characteristics respond to the increasing solar forces, so a coma (charge sheath) forms around them. Discharge jets flare up and move across the surface very much like the plumes of Jupiter's moon, Io. If the charge imbalance becomes too great, the nuclei may explode like an over-charged capacitor, breaking into fragments or vanishing forever.
So, in the case where the discharge is happening far from the sun, it is a situation where they have recieved a large amount of charge while they were close to the sun so when they get to the farther points in their orbit, where the environment has a lower charge, the comet must release the charge to the surrounding environment? I am understanding correctly?
StefanR
Re: Recovered: Holmes gets very bright
Fungus Posted: Wed Oct 31, 2007 2:03 pm Post subject: Reply with quote I'm no physicist (!) but that is a potential explanation, but only if the body had sped (check it, pedant) up enormously. As a typical comet approaches the sun it actually speeds up as it has a very elliptical orbit ie it spends 99% of its existence outside Jupiter and less than 1% approaching the sun. At the sun end it speeds up according to the area law for ellipses (?) and therefore the charge accumulation or in the typical case, loss increases rapidly. At some point it goes from dark glow mode to discharge once enough of a charge difference exists.
This is not typical. The msm ties itself up by saying comets are not asteroids. This spends most of its time near Jupiter! By Jove, in fact! So it is close to home. It only takes 4yrs to orbit.
It may have encountered a discrete stream of particles (from Sol/Lucifer) or even a bulging Birkeland Current BC and has discharged itself in an inappropriate place! In polite society one does not draw attention to this but the msm types have no manners. You might be right it is discharging and that is because there is a difference driving it. But it seems a temporary or transitory phenomenon. Love that word, like a coffee cream chocolate! What is it doing pointing to us or away from us? Could it be that the BC concerned was diddling Mama earth and then moved on to hit the body? That is my guess.
StefanR
Re: Recovered: Holmes gets very bright
Michael Mozina Posted: Wed Oct 31, 2007 5:06 pm Post subject: Re: Holmes Orbit Reply with quote nick c wrote: Comet Holmes' orbit lies entirely within the orbits of Jupiter and Mars, with an orbital period of about 6.8 years. So it never really gets very close to the sun, relatively speaking, vis a vis other cometary orbits. Since the last flare up in the 1890's it has made many orbits around the sun without noticeable incident. The orbit, while not circular does not have a high eccentricity, again, by comparison to other comets. Could this have something to do with the small (or lack thereof) tail? There must be some other mitigating circumstance for the flare up, could it have entered into a strong BC current? I don't know.
It seems to me that there are only two logical options.
A) The comet hit something and it shattered, or at least blew off dust that is now reflecting sunlight.
I don't think we can write off that option just yet, particularly since that last "smiling" image of the comet shows two bright "dots". That could of course be a optical illusion based on the filtering that was used, but there is a possibility that the comet hit something and split in two.
B) It's an electrical phenomenon related charged particle rays coming off the sun, or flowing into the sun.
Quote: If the pressure of the gas is very small during these discharges, there issues (fig. 249, globe not magnetised) from each of the patches a narrow pencil of cathode-rays so intense that the gas is illuminated all along the pencil up to the wall of the tube. This splendid phenomenon recalls our hypothesis according to which sun-spots sometimes send out into space long pencils of cathode-rays.
SCHUSTER has recently (3) made some serious objections to the hypothesis that sun-spots emit direct, rather well-defined pencils of cathode-rays, a hypothesis which was put forward by me in 1899 and 1900, and by MOUNDER in 1904.
You'll note that LASCO-C3 images show long streamers of plasma that flow from the sun in very specific directions, suggesting that electrons flow into the sun from very specific directions as well. These flow channels change over time. The sun's Parker spiral eventually directs the current flows in the outer solar system and would eventually tend to "bend" these streamers of charged particles.
As I see it, there really aren't a lot of other logical possibilities based on the size of photon output increase.
It seems to me that any sort of collision process that might kick out that much material could in fact shatter the comet, or cause it to break up in pieces, whereas it would take quite an electron flow to cause a heavy object to shatter. I suppose we'll have to be patient and see what the mainstream offers as an "explanation" for this event, and what the comet looks like once it quiets down again.
StefanR
Re: Recovered: Holmes gets very bright
Steve Smith Posted: Wed Oct 31, 2007 6:48 pm Post subject: Holmes Reply with quote Yes, there has to have been an unusual event that caused the flare-up in Comet Holmes, since it has made many orbits of the sun without brightening. In the Picture of the Day, we did not mention Comet McNaught, although the ion tail was shown to attract the solar wind and actually decelerate it by 50%. That effect demonstrates a significant potential. As I wrote before, but received no reponse, the relative increase in potential could have affected a large region between the orbits of Mars and Jupiter.
Hale-Bopp continues to discharge and has left behind another ion tail extending hundreds of millions of miles. Holmes 17P could have undergone an acceleration due to increased charge in the environment — itself a charged body — thereby generating more energetic discharge events on its surface. It could have attracted a more concentrated current flow initiated by the other comets, by some activity on Jupiter or by some strong variation in the sun's ion flux. No one can be sure.
No one knows much about comets, in the first place, so explaining their strange behavior is doubly hard. Most conventional sources use the same data stream, so they don't vary in their explanations. We're the only ones to see cometary activity as mundane because it is taking place in a solar system that exhibits experimentally verifiable cause and effect relationships.
Although the details of what is happening are mysterious on the fundamental scale — how does electricity flow, where does the current come from and where is it going, are galaxies transitory electrical phenomena — the macroscale events can be identified because we experienced them when we electrified our civilization. Holmes 17P must be explainable in simple terms, otherwise our theoreitcal approach is flawed.
There will be more articles about comets and why they behave the way they do as more observations come in.
StefanR
Re: Recovered: Holmes gets very bright
Biknewb Posted: Wed Oct 31, 2007 8:06 pm Thinking about the reaction of Holmes to another comet's tail, I could only conclude that it would make it discharge less. In the tail of McNaught the solar wind has been "used" to some degree. Positive charges have been (partly) neutralised. This leaves an environment with more electrons than the "fresh" solar wind. OTOH if Holmes is rather positive, due to its orbit, then the tail of McNaught might make it discharge the other way: accepting electrons. I have no idea wat this would mean in practice in terms of EDM.
StefanR
Re: Recovered: Holmes gets very bright
Michael Mozina Posted: Wed Oct 31, 2007 10:18 pm Post subject: Re: Holmes Orbit Reply with quote Krackonis wrote: If it hit something there would be a discharge first. Then it would die down. There was no "flash" at the beginning, just a raising of the luminosity. This lends me to suspect that the comet entered a Birkeland Current flowing out or in to a planet or the Heliopause. Wink
Well, I tend to agree with you, but let me play devil's advocate for a moment.
You and I assume there will be a discharge, whereas the mainstream will not assume that. Even in their way of thinking, we should have seen a flash at impact, but who can be sure anyone was looking at the comet at exactly that second? An impact with the comet would probably kick up a lot of dust and that dust would reflect sunlight. I doubt the mainstream is going to rule out that possibility, and even in an EU universe, objects can and do run into one another, so even we can't technically rule it out.
In theory however, an impact that could kick out that kind of debris, would probably leave other telltale signs, including the possibility of splitting the objects into several parts. I think the mainstream is likely to explore this option fully, and if that doesn't work, they'll want to sweep the event under the carpet, and pretend it never happened. At that point they'll be out of viable options that don't involve current flow, and we all know that nobody in the mainstream can mention the word current flow in plasma, and electric comets, or the jig is up, and their whole show is busted.
StefanR
Re: Recovered: Holmes gets very bright
Michael Mozina Posted: Wed Oct 31, 2007 11:22 pm Post subject: Re: Holmes Reply with quote Steve Smith wrote: Yes, there has to have been an unusual event that caused the flare-up in Comet Holmes, since it has made many orbits of the sun without brightening. In the Picture of the Day, we did not mention Comet McNaught, although the ion tail was shown to attract the solar wind and actually decelerate it by 50%. That effect demonstrates a significant potential. As I wrote before, but received no reponse, the relative increase in potential could have affected a large region between the orbits of Mars and Jupiter.
I've been entertaining the notion of current channels that form in the Parker Spiral. Let me explain. It's possible that the current that flows into the sun from our universe follows the Parker spiral filament channels inward towards the sun. IMO, the Parker spiral process creates/organizes electrified arms of plasma around the solar system that tend to funnel the current into and through the spiral arms, much like galaxies carry electrical currents to the core though their spiral arms. Those arms of rotating plasma funnel and channel the electron flow from the heliosphere into relatively thin channels of current as they approach the inner solar system. Since Jupiter is the largest of the mass bodies, it may have a significant effect on such current streams as the reach into the inner solar system. When the comet happens to traverse one of these thin plasma streams it becomes a large conductor, and it gets lit up like a Christmas tree because of the increase in current flow while it's still inside the current channel. Once it's passes through this channel it should settle back down almost as fast as it started.
Quote: Hale-Bopp continues to discharge and has left behind another ion tail extending hundreds of millions of miles. Holmes 17P could have undergone an acceleration due to increased charge in the environment — itself a charged body — thereby generating more energetic discharge events on its surface. It could have attracted a more concentrated current flow initiated by the other comets, by some activity on Jupiter or by some strong variation in the sun's ion flux. No one can be sure.
Well, I tend to favor that concentrated current idea you mentioned over anything else I can think of. When I look at the LASCO images, I see very concentrated plasma streams coming from the sun, so there must be very concentrated electron streams flowing into the sun as well. My guess is that the comet can sometimes cross that current stream between Jupiter and Mars, and it lights up.
Quote: No one knows much about comets, in the first place, so explaining their strange behavior is doubly hard. Most conventional sources use the same data stream, so they don't vary in their explanations. We're the only ones to see cometary activity as mundane because it is taking place in a solar system that exhibits experimentally verifiable cause and effect relationships.
I think that last part of your statement is very important point for us to remember. We do in fact see the universe quite differently than they do, and we see things from a cause/effect perspective that is very different from the mainstream headset. It's my hope that events like this one will create enough of a "stir" in the media and within the mainstream to get the mainstream media to open up their minds to the notion of electrical currents inside the solar system. It seems like this is a golden opportunity to spur change within the industry, by getting the media to focus on the issue.
Quote: Although the details of what is happening are mysterious on the fundamental scale — how does electricity flow, where does the current come from and where is it going, are galaxies transitory electrical phenomena — the macroscale events can be identified because we experienced them when we electrified our civilization. Holmes 17P must be explainable in simple terms, otherwise our theoreitcal approach is flawed.
Sure, but as you said earlier, you and I see a direct cause and effect relationship between currents in space and objects in space, whereas from their limited perspective, mysteries are common, and nobody wants to mention electrical currents to their boss. Smile
Quote: There will be more articles about comets and why they behave the way they do as more observations come in.
Steve
Indeed. I guess what I really like about this particular event is that it took place on such a huge energy scale, and it already has global interest, and media interest as a result. Comets simply don't increase their brightness a million fold in a few hours very often. IMO this is definitely one of those catalyst type events that will have long term repercussions, mainly because the options that could explain such an event are quite limited. IMO there are only two viable scientific options. Either the comet hit something at very high velocity, or it entered a current channel. Not many other forces of nature could explain a million fold increase in brightness over just a few hours, and also sustain that brightness over an extended window of time.
Fortunately for us, as far as explaining solar system process are concerned, the use of "dark" forces to explain solar system activity is almost as "taboo" in mainstream publications as using electrical currents. As a result, it will be very interesting to see what comes of this event over the long haul. They may just have to bite the bullet and accept the role of electricity in solar system processes, if only to get the press off their back and to give them "some kind" of answer.
StefanR Posted: Fri Nov 02, 2007 2:59 pm Post subject: Reply with quote biknewb wrote: Looking at the dates in the graphs, it seems more likely that the brightening caused the spike.
Quote: AURORA WATCH: Earth is exiting a solar wind stream that sparked beautiful polar auroras on Oct. 25th. The chances for a follow-up display tonight are low: gallery.
I had some trouble as to find at what exact position the ACE (which produces the spikegraph) is measuring it's data. But of course we are dealing with a three dimensional space and suppose a solar wind stream is a cause of the flaring it is unknown what exact dimensions and direction it took. ACE could have measured the stream at it's edge and what Holmes encountered was maybe the full headwind. Also note that there is a proton spike early 24th and sadly the data preceding is missing.
And maybe not only an transverse solar wind stream is involved but there is also an longitudonal component of energy transfer http://www.meyl.eu/go/index.php?dir=10_ ... sublevel=0 Confused just groping in the dark Confused
StefanR
Re: Recovered: Holmes gets very bright
Mgmirkin Posted: Fri Nov 02, 2007 6:06 pm Looking at the images:
From the 3rd image (Comet Holmes magnitude) it appears that Holmes began to brighten significantly between the 23rd & 24th of October, where it when from magnitude 18 to magnitude 8 in the space of about 24 hours, yeah?
Then between the 24th and 25th, it appears to have ascended even further from magnitude 8 to appx magnitude 3 - 2.5 (fluctuating between magnitudes 2 & 3, depending when observations are taken)?
From the 1st image, 1st line, it appears there was an "event" around late on the 25th / early on the 26th, after which it went back to quiescent. Not sure what specifically that line represents, as I'm not familiar iwth the specific notation. Anyone with more tehcnical expertise care to chime in on the specifics of the various lines?
1st image, 2nd line (again, not sure what Phi refers to; so many bits of jargon, so little time!), it appears that around the 24th the readings were all over the chart. Or more specifically, there were time where it hit 0 and times where it hit 360. Almost looks like a double line (top & bottom; subsequently, the majority of the graph centers around 180).
1st image, 3rd line, it appears (if I read it right) that the solar wind began to pick up density gradually early on the 24th, then spiked around mid to late on the 25th, after which it returned to normal.
1st image, 4th line, it appears that the solar wind was at a baseline of 300-400 Km/s, on the 24th, then spiked quickly to 500, 600 & 700 Km/s half way through the 25th. Speed reduction was gradual over time. Isn't that an approximation of CER Bruce's work on electricity in space and stellar atmospheres? IE, a discharge tends to brighten exponentially, then die off slowly? I'll have to look for the CER bruce materials I posted to another thread. I'd love to have a comparison! See if he was right, that solar flares and such are basically synonymous with electrical discharges...
1st image, 5th line, we also see that the temperature spikes half way through the 25th (not familiar with the notation, so perhaps someone can put the scales in laymen's terms, so the "rest of us" can understand the order of magnitude the temperatures and such jump?). It jumps from a baseline of about 1.0E+04.75 {?} to 1.0E+05, then jumps to fully 1.0E+06, before decaying back to a little over 1.0e+05 (with minor fluctuations thereafter).
So, it seems that the largest event for the solar wind occurred mid way through the 25th. It appears that density, speed and temperature all jumped pretty dramatically at about the same time. I'm assuming this was from a solar flare, CME or similar event?
But it appears that Holmes began to respond before the solar wind measurements dramatically increased. This makes me suspect that whatever caused the events affected the comet BEFORE it affected the sun. To me, personally, this suggests that the cause may have been external to the system, as opposed to internal. Consider, what would happen if the external current were to jump up a notch or two. Would the sun be affected first, or would the comet?
Perhaps there was an external surge. The inflow of current caused the comet to begin brightening on the 23rd, jumping from 18th to 8th magnitude between the 23rd and the 24th.
Consider that then the external currents' effects may have reached the sun and then "bounced," so to speak. If the timing was just right the external inflow of current would perhaps have bumped the comet from 18th to 8th magnitude. Then caused a flare or CME on the sun, which would have also impacted or effected changes on the comet, bumping it from 8th magnitude to 3rd - 2.5th magnitude...?
I don't know if I'm completely off base here. But it seems to me that whatever affected the comet did so fully a day before it affected the sun.
That might also explain the stepped pattern of the Temp, Speed, & Density mesurements. Notice how they appear to spike, drop slightly, then spike even higher? Then eventually fade away. Is that consistent with a single event, or a series of events?
Something to chew on, eh?
StefanR
Re: Recovered: Holmes gets very bright
Posted: Fri Nov 02, 2007 6:12 pm
http://www.atmob.org/gallery/showimage.php?id=719 Quote: Submitted by Mario Motta M.D. on 10/31/2007 14:57:46 comet Holmes with jet, 10/30/07 minor processing with curves brings out a jet in the fan area of the comet.
StefanR
Re: Recovered: Holmes gets very bright
DustyDevil Posted: Fri Nov 02, 2007 6:18 pm The situation is not as simple as that image makes it seem. When Holmes was discovered — on November 7, 1892 — there was no such planetary alignment; however, Holmes had just crossed the plane of the ecliptic. You can check the relevent positions for yourselves by using JPL's Small-Body Database Browser at the following link:
If your browser is Java enabled, you can use Orbit Diagram applet to plot Holmes position vs. the rest of the solar system for any date you'd like to investigate.
StefanR
Re: Recovered: Holmes gets very bright
Posted: Fri Nov 02, 2007 8:52 pm Post subject: Reply with quote Quote: Secrets of High-Power Comet Observing Through the telescope, you'll see this activity as jets, linear rays that flow in the Sunward direction. A jet can appear as a single ray or a fan of several arcing rays. High power should reveal any strong sources near the nucleus. If jets are suspected, record their positions, switch to moderate magnification, and study the shape of the inner coma. If the coma is very bright, the jets might be lost in the glow, but the material they have ejected can surround the inner coma in a series of parabolic hoods. The farther a jet extends from the nucleus, the lower its surface brightness becomes, so moderate and low magnifications should be used to trace out its greatest extent. Generally, long jets will have a strong linear base that gradually curve toward the antisolar direction.
One of the most curious features within a jet is a knot of material that can easily be misidentified as a secondary nucleus. Secondary nuclei usually migrate tailward over several nights. So be leery of bright spots in the Sunward direction; these are probably clumps of gas and dust shooting off the nucleus within the jets. Many times the knots are brighter than the jets themselves, so a bright knot in a faint or invisible jet will certainly cause alarm! Comet Hale-Bopp exhibited several intense knots, especially in one strong and persistent north-pointing jet, during its passage around the Sun. http://www.skyandtelescope.com/observin ... page=3&c=y Quote: Magnitude Data of Comets in order of Day of Perihelion http://www.aerith.net/obs/comet.html#17P.2007
Quote: * 17P/Holmes
IIIYYYYMnL YYYY MM DD.DD eM/mm.m:r AAA.ATF/xxxx /dd.ddnDC /t.ttmANG ICQ XX*OBSxx 17 2007 10 05.74 S[14.1 HS 40.0L 4 257 ! 0.4 ICQ XX YOS04 17 2007 10 06.67 S[14.1 TA 40.0L 4 257 ! 0.4 ICQ XX YOS04 17 2007 10 24.55 I 3.7 YG 6.6R 10 9 ICQ XX YOS04 17 2007 10 24.55 I 3.5 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 24.63 I 3.2 YG 6.6R 10 9 ICQ XX YOS04 17 2007 10 24.63 I 3.0 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 24.71 I 2.9 YG 6.6R 10 9 ICQ XX YOS04 17 2007 10 24.72 I 2.8 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 24.80 I 2.9 YG 6.6R 10 9 ICQ XX YOS04 17 2007 10 24.80 I 2.8 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 27.74 S 2.7 YG 6.6R 10 3.5 D2 ICQ XX YOS04 17 2007 10 27.74 I 2.5 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 28.46 S 2.4 YG 6.6R 10 5 6 ICQ XX YOS04 17 2007 10 28.46 I 2.4 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 29.54 S 2.5 YG 6.6R 10 6.5 d6 ICQ XX YOS04 17 2007 10 29.54 I 2.3 YG 0.0E 1 8/ ICQ XX YOS04 17 2007 10 30.45 S 2.5 YG 6.6R 10 8 6 ICQ XX YOS04 17 2007 10 30.45 I 2.6 YG 0.0E 1 9 ICQ XX YOS04 17 2007 10 31.47 S 2.4 YG 6.6R 10 9 6 ICQ XX YOS04 17 2007 10 31.47 I 2.7 YG 0.0E 1 8 ICQ XX YOS04
Posted: Fri Nov 02, 2007 10:53 pm Quote: UT 2007.10.31 03:16. This 50 minute exposure was stacked from 200 15-second frames collected over 2.5 hours. The image is 12.1 arcmin square http://www.cloudbait.com/gallery/comet/holmes.html
Quote: The profile of the overexposed comet head is shown here. The flat top is an artifact of the overexposure. The coma diameter over five nights has increased from 3.3 arcminutes to over 13 arcminutes. The comet now appears nearly half the size of the Moon. At its current distance, that means its true physical diameter is almost 1 million kilometers, or about 70% of the size of the Sun. That makes this comet the second largest object in the Solar System.http://www.cloudbait.com/gallery/comet/holmes.html
Quote: M. Jäger image obtained on 2007 October 31.8. This is a combination of three 180-second exposures obtained using a 30-cm Deltagraph, a Sigma 6303 CCD camera, and a blue filter. Although a few overly-processed images from October 29 and 30 hinted at this type of tail, which led to excessive discussion on the internet, this is the first image to conclusively prove its existence. The tail appears extremely short, because the tail is heading almost directly away from our line of sight.
Posted: Sat Nov 03, 2007 12:30 am Post subject: Reply with quote ok DATA-BONANZA!!! I'm not going to link all the images but there's a lot of data overhere:
http://astrosurf.com/buil/holmes/obs.htm Comet 17P/Holmes outburst 17P/Holmes - Date: 24.892 / 10 2007 - After normalisation by the moon spectrum - Negative display - Mg I triplet region. 17P/Holmes - Nucleus region (comet spectrum / moon spectrum). The spectrum is very flat - Sun light reflected by dust dominate. 17P/Holmes - Coma region (comet spectrum / moon spectrum). Very faint lines and narrow are detected (the 5165 A is the C2 band). 17P/Holmes - Date: 24.849 / 10 2007 - After normalisation by the moon spectrum - Negative display - Na I doublet region. 17P/Holmes - Mg I region - Observed spectrum (C11 + Lhires III - R=6000). The dust reflectance dominate the inner region, but the C2 band emission is now evident - it is the explanation for the green color of outer part of the comet. The faint feature at 513 nm is real (also visible the Oct. 24). Photometric profile of 17P/Holmes along the north-south direction from the Na I spectra (binning along the spectral axis). Some Larson-Sekanina processing. Note the quasi annulus structure and presence of jet. The covered field is 4.4' x 4.3'.
