Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Fay on Oct 17, 2010, 13:18:52

Title: Bubble Nebula in Cassiopeia
Post by: Fay on Oct 17, 2010, 13:18:52

Went out to polar align EQ6 & ended up staying out for a while.

This is 10x600, SW120, Atik 314L, ha, o.8fr. 171010

As the nebula reached the zenith, the guiding seemed to suffer. I have only stacked 10 subs here, but have got another 3. The guide graph looked good all the time, so was surprised to see stars sllghtly elongated.

(http://farm5.static.flickr.com/4106/5089344088_25c6478a02_b.jpg)
Title: Re: Bubble Nebula in Cassiopeia
Post by: MarkS on Oct 17, 2010, 16:08:53

Fay,

That really is a very good image.  It's very clean, very detailed and processed very nicely to bring out the contrast.  The brighter part inside the bubble has burnt out but not severely.

If this had been taken at DSC I could understand it, but I guess this was taken from home?  Which Ha filter are you using - in particular how narrow is it (12nm or 6nm)?  How were the conditions - I decided not to image because of tooo much moon - maybe a wrong decision!

The guiding problem you described is flexure - something has moved slightly as gravity has started to act from a different direction.  Maybe the guidescope has flexed relative to the main scope or maybe one of the cameras has flexed relative to its scope.

Well done.

Mark
Title: Re: Bubble Nebula in Cassiopeia
Post by: Fay on Oct 17, 2010, 16:34:33
Thanks a lot Mark. Well the filters are the Atronomik one's, I was looking at the halo around the large star & when looking at other images, I was thinking it is a common problem as there are a lot of spikes around for that star!


It was weird as the guiding looked very good, it seemed that the slightest  movement would produce a bad sub. Perhaps the balance was not right, & as it all changed positions it showed up.

If I put the bad 3x subs into the image, there was not a lot of difference in quality, & it is another 30 mins!
Yes did it last night.

Title: Re: Bubble Nebula in Cassiopeia
Post by: MarkS on Oct 17, 2010, 17:38:40

Is it an Astronomik 12nm filter or a 6nm filter (the 6nm filter is the expensive one)?

Adding 3 subs to 10 subs is only a 30% increase - it will make hardly any difference to be honest.  To see a difference you need to double the number of subs and even then the difference is marginal. 

Do an experiment where you compare the quality of 1 sub, 2 subs, 4 subs, 8 subs, 16 subs - it's very instructive.  it gives you an idea of what improvement expect when doubling your total exposure time.

Mark
Title: Re: Bubble Nebula in Cassiopeia
Post by: Fay on Oct 17, 2010, 17:41:58
Thanks Mark. I am thinking they are the 12m filters
Title: Re: Bubble Nebula in Cassiopeia
Post by: Mac on Oct 17, 2010, 18:03:46
nice image,


Mac.
Title: Re: Bubble Nebula in Cassiopeia
Post by: mickw on Oct 17, 2010, 18:12:51
That's really nice Fay, loads of detail
Title: Re: Bubble Nebula in Cassiopeia
Post by: Fay on Oct 17, 2010, 18:16:02
Oh thanks a lot, nice of you
Title: Re: Bubble Nebula in Cassiopeia
Post by: RobertM on Oct 23, 2010, 14:09:21
Hi Fay,

Sorry I missed this earlier, that's a really great result; nicely focused, well processed with good detail.  I'm sure you could extract a knats of detail from the shark in the bubble and I still think your black points are set a tad too high missing some nebulosity (I could be wrong in this case!).  They are personal finer points that don't detract from an excellent result.

Robert

Title: Re: Bubble Nebula in Cassiopeia
Post by: Carole on Oct 23, 2010, 14:48:53
Very nice Fay
Title: Re: Bubble Nebula in Cassiopeia
Post by: Daniel on Oct 23, 2010, 15:11:22
That's a fantastic result Fay, you've really balanced out the bright core and the surrounding nebulosity well, Love how sharp the detail is while keeping the image noise free!

Daniel
:O)
Title: Re: Bubble Nebula in Cassiopeia
Post by: The Thing on Oct 23, 2010, 21:43:00
Stonking image Fay. Congratulations!
Title: Re: Bubble Nebula in Cassiopeia
Post by: Fay on Oct 24, 2010, 09:02:57
Thankyou everyone, very kind of you
Title: Re: Bubble Nebula in Cassiopeia
Post by: Mike on Oct 24, 2010, 09:35:11
Really nice image Fay. Some of the best detail i've seen in the Bubble.
Title: Re: Bubble Nebula in Cassiopeia
Post by: Fay on Oct 24, 2010, 10:46:15
That is nice of you Mike, thanks
Title: Re: Bubble Nebula in Cassiopeia
Post by: Ian on Oct 24, 2010, 11:45:21
looks shiny :)