Isn't astronomy just a fantastic hobby! You just never know what the universe will throw at you!

In most cases I would prefer to know!

Seanie wrote:

Isn't astronomy just a fantastic hobby! You just never know what the universe will throw at you!

Just like the wife

wow, this thing has become very bright, nice images lads BTW, tonight's the night to catch it as the weather is turning sour tomorrow.

Just had a look at it for a second night, first in the binoculars and it is much bigger tonight and possibly a little brighter than last night. In the telescope it is simply stunning. Big circular coma, a point like nucleus and a quadrant of the coma showing a fan like mini tail to the west completely contained within the coma.
Gotta go and look again.......

Hi everybody, it's not often you get a chance to make a first post at a time like this.
The comet has definitely brightened slightly, although it is difficult to make an accurate estimate of magnitude in such a bright moon. It is definitely brighter than Delta Persei. My best guess would be mag 2.5. Appearance is similar to last night, the nucleus appears to be more compact, but the coma is of a similar size, and overall, the yellow colour is paler. The comet has moved slightly in the direction of Mirfak, apparently, it is predicted to pass quite near Mirfak in a few days, hopefully it will remain visible until then.
I hope the skies stay clear for you all.

Just had a look at it for a second night, first in the binoculars and it is much bigger tonight and possibly a little brighter than last night. In the telescope it is simply stunning. Big circular coma, a point like nucleus and a quadrant of the coma showing a fan like mini tail to the west completely contained within the coma.
Gotta go and look again.......

That's exactly how I see it too Michael.

I've never seen the likes of this before...simply amazing!
Make sure you see this in a telescope!

here is a pic cropped from a shot taken at iso800 F5.6 300mm .6secs

Tried to capture some detail in it, but I am not sure. It does however look a bit like this in a small scope.

Just had a look at it for a second night, first in the binoculars and it is much bigger tonight and possibly a little brighter than last night. In the telescope it is simply stunning. Big circular coma, a point like nucleus and a quadrant of the coma showing a fan like mini tail to the west completely contained within the coma.
Gotta go and look again.......

Dam clouds...

The bright point like nucleus wasn't visible last night. The 'fan' is fairly obvious too. It looks almost as if its a cone pointed towards us with a bright light on top and slightly lit from one side. Hopefully the clouds will blow over.

Very unusual. We've got a ton of thin cloud & all we can see here is the moon and maybe 3 stars but the comet is still very visible.
I didn't think there'd be any point in setting up the scope so I took a gander through 7x50s (Lidl's best). Even in the binos it looks like it's bigger than it was yesterday. What a weird object.

Oh, Trev, get out that scope! Well worth a look even in hazy skies!
It'd definetly bigger and brighter than last night. Somewhere about the mag. 2.3~ish I reckon tonight.

Just had a look at it for a second night, first in the binoculars and it is much bigger tonight and possibly a little brighter than last night. In the telescope it is simply stunning. Big circular coma, a point like nucleus and a quadrant of the coma showing a fan like mini tail to the west completely contained within the coma.
Gotta go and look again.......

This pretty much exactly describes what I saw this evening through my 8" Dobsonian at 50x - a beautiful, almost circular halo with a very bright, star-like point dead centre, with a bright, fan-like, short tail emanating from the nucleus but contained with the circular coma. At 100x plus I thought I could make out the very diffuse outer coma that John O'Neill described above, although it was hard to be sure with the full Moon so near by.

Does anyone have any idea at this stage what caused this comet to get so bright so suddenly?

Just managed to get a look through a gap in the clouds. Even with the naked eye you can see that it's moved towards Alpha Persei since yesterday and in 10x50 binoculars it now looks like a yellow globular cluster where as yesterday it looked like a star. Fascinating to see something change so much in a day!

Here's my full report: www.bartbusschots.ie/blog/?p=565

Bart.

Does anyone have any idea at this stage what caused this comet to get so bright so suddenly?

Nope, but I did find this:

www.astro.uni-bonn.de/~dfischer/mirror/306.html

A most amazing eruption is occuring on comet 17P/Holmes which was at 17 mag. at best but on October 24 suddenly began to brighten like crazy: Now (afternoon UTC) it has already reached 3rd magnitude and is easily visible to the naked eye, as reports from Japan indicate: "Perseus does not look 'Perseus' familiar to us due to the bright stellar object now." The comet looks like a bright, yellow star, and only magnification reveals a fuzzy coma around the dusty core. Holmes was discovered in 1892 thanks to a similar outburst, and hope is that the further development will be similar now: the coma should expand over time but stay bright for a week or more. "Following the initial stages of the [1892] outburst, the comet's total magnitude faded only very slowly and it remained visible to the unaided eye for about 3 weeks," advises comet guru John Bortle: "During this interval the coma expanded dramatically (as might be expected), reaching 20'-30' in size before its outer regions began to drop below the sky background." Moreover, there was a second outburst "of almost equal amplitude to the first one, about 75 days following its 1892 November brightening. Thus, I would urge everyone to watch very carefully for a possible repeat of this secondary event about the turn of the year."

and just one more shot..........despite the cloud, I waited for two and a half hours tonight and finally got a break to get 75 x 0.3 seconds of images. This is one weird beastie.

Hi,

The Comet 17P/Holmes is quite different last night (25/26 Oct 2007)

Naked-eye estimate mag 2.4. at 22:00 UT.

Shortly afterwards did a telescopic observation with 25cm refl. at 181x:

1. Faint diffuse halo not seen tonight.
2. Bright circlular disc halo, 2 min of arc across
3. Very Bright fan towards SW.
4. Almost stellar very bright central condensation (at centre of halo).

Unlike previous night the no longer stellar in 8x50 finder (i.e. tiny disc).

All this despite the large bright full moon nearby.
Thin cloud, but uniform

John

Hi,

1. Faint diffuse halo not seen tonight.

John

Yes, but in Phoenix's (slightly overexposed) photo above you can make out a faint outer halo.

Just as an aside on this I had a weird dream concerning this comet - a group of us were observing it and speculating as to the lack of a tail when one of us started screaming at the top of his voice "Don't you get it?? That's what a Comet looks like from the front - It's coming straight at us!!"

Then I woke up

Just as an aside on this I had a weird dream concerning this comet - a group of us were observing it and speculating as to the lack of a tail when one of us started screaming at the top of his voice "Don't you get it?? That's what a Comet looks like from the front - It's coming straight at us!!"

Then I woke up

Actually, there is a grain of truth in this - according to my edition of Starry Night Enthusiast, Holmes 17P is currenty close to opposition w.r.t. the Earth, so the tail should be be streaming directly away from us, which would explain why we only see a circular and no tail as such - perhaps it's hidden behind the coma/nucleus. Of course, the comet is definitely not heading towards us, but it's appearance is as it would be if it was.

Frank and I headed to Doonbeg in Clare last night, a fantastic site illuminated only by the moon.

We had a good look at this comet through the 20", there is definitely a steller like nucleus with a fan shaped wedge mini tail completely contained within the coma, the coma had a very definite outline with one side of it been definitely fuzzier then the other, the side with the mini tail, maybe this is the starts of a dust tail emerging ? this thing really looks like it is heading towards us
To me, the outer area of the coma looks a little more intense then the area of the coma halfways between the centre and the edge, almost like a shock wave.
I reckon that given the illumination range of this thing, it will be difficult to get an image that represents the visual view through a scope.

Here is all I got from last night 21:50 UT/FL1200/10mm/120X
I had barlows at the ready to get in closer but fast thick cloud took any more viewing away for the rest of the evening.

I had no time to see and place in any other stars in the FOV

Very bright point like nucleus, very circular coma, and yes a delta or fan shape within. I had the same thought, that the tail was perhaps on the side away from the Earth, and that it is much wider than the comet itself.
Or that there is no tail yet and the material is jetting out evenly from the whole comet in a massive outburst. Perhaps this material will form a tail when it is finished flying out in an even way?
Or the tail is cone shaped and is on this side of the comet, and very wide ?

Deirdre Kelleghan
Irish Astronomical Society

My thoughts also Deirdre.
I had a look in starrynight for this comet, it is moving very slowly and is sitting between Mars and Jupiter and is not getting nearer to the Sun. With a coma that big, there just has to be a tail behind it, we are currently between it and the sun, so the tail must be pointing away from us, behind the nucleus.

Deirdre, how sensitive are the cameras on Cassini in orbit of Saturn, looking at starrynight, Saturn has an almost perfect side on view of this comet, I'd bet a side on image of this comet would show a nice big tail.

this thing really looks like it is heading towards us

My thoughts as well (was about to double post that until I saw your words Dave!). It is a slow moving comet, but after over a day since the outburst, you would expect to see some sort of trail.

Seanie.

saturn.jpl.nasa.gov/spacecraft/instruments-cassini-intro.cfm

What an interesting idea Dave to use Cassini to check out the comet.
Above link to instrument data, Cassini telescopes are fitted with ccd cameras. You have all seen the quality of the images achieved even though these cameras are now well over perhaps 12 - 15 years old.
The mission launched 10 years ago but the cameras were fitted well before that and most likely are even older.

Now the mission is almost totally governed by finance, every move of the spacecraft is planned well in advence. They have a program of must do's and a list of flyby's already well advanced.

They can and have altered set plans if something strange needs a close look. The mission is to Saturn and Titan and only things like the outburst from Enceladus can make a change in the plan.

Every move of the spacecraft is bugeted, every uplink and download is planned down to the cent. It would be great and very interesting to see this available spacecraft checking this out. I have made an enquiry to this effect and I will let you know the answer.

Perhaps other robotic spacecraft could be in a more flexible program and take a look also.

Anyone got a handle on what the boffins are saying re Holmes and its shape, color, properties et cetra ?

Deirdre Kelleghan
Irish Astronomical Society

saturn.jpl.nasa.gov/spacecraft/instruments-cassini-intro.cfm

I have made an enquiry to this effect and I will let you know the answer.
Deirdre Kelleghan
Irish Astronomical Society

Thats great Deirdre, it think it would be unique to have a stereoscopic view of this comet, I think that would be worth alot.!

I reckon that given the illumination range of this thing, it will be difficult to get an image that represents the visual view through a scope.

Well, here is a stack of 13 separate shots taken by Dave & I last night through the
20'' With a Canon 350D using various exposure and iso settings.
All the images and the resulting stacked image I have left unprocessed.

I think it gives a very good impression of what we saw through the scope
but it doesn't show the pin point nucleus that is so evident in the wide angle eyepieces.

The impressive thing was to see the pin-point background stars around it
which gave fantastic contrast to the size and fuzziness of this amazing comet.