Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Oct 29, 2007, 06:25:24

Title: Hello from 17P/Holmes
Post by: MarkS on Oct 29, 2007, 06:25:24
Sorry to post here, in the Introductions, but here are some images of 17P/Holmes I took from Sidcup last night (Sun 28 Oct) between 11pm and midnight GMT.  (Maybe Rick can move the thread to somewhere more appropriate).

Firstly showing the location 17P/Holmes in Perseus (Nikon D70 @ 55mm and at 200mm):
http://homepage.ntlworld.com/the_shelleys/photos/holmes_in_perseus.jpg (http://homepage.ntlworld.com/the_shelleys/photos/holmes_in_perseus.jpg)
http://homepage.ntlworld.com/the_shelleys/photos/holmes_widefield.jpg (http://homepage.ntlworld.com/the_shelleys/photos/holmes_widefield.jpg)

Then a couple taken with a DSLR on a Celestron C11 - 8 images of 20 sec stacked and post-processed using Photoshop curves:
http://homepage.ntlworld.com/the_shelleys/photos/holmes_c11_1.jpg (http://homepage.ntlworld.com/the_shelleys/photos/holmes_c11_1.jpg)
http://homepage.ntlworld.com/the_shelleys/photos/holmes_c11_2.jpg (http://homepage.ntlworld.com/the_shelleys/photos/holmes_c11_2.jpg)

I think the weird effect of the comet having "3 cores" is probably due to 2 bright stars sitting behind the coma.

Mark
Title: Re: Hello from 17P/Holmes
Post by: Ian on Oct 29, 2007, 07:22:29
I've moved this to astrophotography.

Good photos there Mark. There some discussion going on at the moment as to whether thosebright spots are actually bits of a split core...
Title: Re: Hello from 17P/Holmes
Post by: Rick on Oct 29, 2007, 09:34:07
Sorry, Mark. I should have modified your ID a while back. Slipped my mind. I've adjusted things now.
Title: Re: Hello from 17P/Holmes
Post by: JohnP on Oct 29, 2007, 10:39:11
Excellent Mark - Well done for capturing & great images - I need to give this a try myself - John
Title: Re: Hello from 17P/Holmes
Post by: Mike on Oct 29, 2007, 21:27:57
Wow!! This comet sure is obvious. I knew there was one up there but had no idea where it was at all. I got off the train today at Chelsfield and was walking home when I looked up at Perseus. I could clearly see there was a bright star there that shouldn't have been there. I guessed it was the comet and checked on Heavens Above when I got home and sure enough it was. Through the scope it was identical to these photos, including the multiple core, so maybe it has broken up?


Anyway, if you haven't seen it yet get out and look, you can't miss it !!
Title: Re: Hello from 17P/Holmes
Post by: Whitters on Oct 30, 2007, 00:09:47
Fantastic shots Mark, What an amazing comet.
Title: Re: Hello from 17P/Holmes
Post by: MarkS on Oct 30, 2007, 06:23:18

I took another image last night and have added it to the gallery. 
http://gallery.orpington-astronomy.org.uk/displayimage-346.html (http://gallery.orpington-astronomy.org.uk/displayimage-346.html)

Now the comet has moved position, it is clear that 2 of the 3 bright points in inner coma from the previous night were actually stars.  There is now just a single bright point.

Can anyone explain the greenish halo around the coma? 
Title: Re: Hello from 17P/Holmes
Post by: JohnP on Oct 30, 2007, 07:46:37
Mark - great image & well processed & exactly as it looked last night through the eyepiece - What amazed me was the size & how perfectly circular it looked...

I guess the halo is due to all the outgassing the comet is doing.. Green must be due to colour of the components that are coming off....

I really must try & image this myself...

Nice one - John
Title: Re: Hello from 17P/Holmes
Post by: Fay on Oct 30, 2007, 07:50:22
Really good Mark, really clear. Must have a go myself



Fay
Title: Re: Hello from 17P/Holmes
Post by: Ian on Oct 30, 2007, 09:24:32
The only explanation I can come up with regarding the circular coma is,

it must be heading straight for us!!!!!  :o
Title: Re: Hello from 17P/Holmes
Post by: Mike on Oct 30, 2007, 09:36:20
Quote from: Ian on Oct 30, 2007, 09:24:32it must be heading straight for us!!!!!  :o

Aha !! My alien invasion bunker (from the Martian Invasion post) will come in useful after all !!
Title: Re: Hello from 17P/Holmes
Post by: Rick on Oct 30, 2007, 11:17:15
Quote from: MarkS on Oct 30, 2007, 06:23:18
Can anyone explain the greenish halo around the coma?
It's not un-common in bright comets. Hyukataki was also very noticably green. Anyone in a position to take its spectrum?