Here's a preview of my latest attempt at the picture that refuses to be taken - it was taken just before dawn this morning:
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/normal_horse18102009.jpg)
Details: H-alpha modified Canon EOS 350D on Celestron C11 with F6.3 focal reducer and CLS filter to cut out the residual light pollution at Blacklands.
I did 12 ten minute exposures but only 7 were usable because of drift, flexure or mirror shift - I'm not sure which. Ambient temperature was 2-3C which suits the DSLR well but the seeing was not very good.
Here is the full-frame image 3x3 binned but with no darks or flats applied yet:
http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/horse18102009.jpg
Mark
Mark,
Excellent image, and worth staying up for, in weather that would freeze the balls off a brass monkey.
When I made a brief appearance from the tent this morning at 6.03am (I can read the stars well, now), and saw the 2 laptops still running, thoughts of Scott's trip to the Antartic flashed through my mind, and I thought I could see a frozen astronomer lifeless in the chair, so I was surprised when I called out and got a reply, and a small shadowy figure approached and said he had been up all night. Well fair play to you, and it's been worth it, I think. Congratulations.
I still think personally that weird french s**t played a big part in it. ;)
They are not diffraction spikes on the LHS of the image, are they? :)
Tony G
Very nice image Mark
very nice image.
Mac
Excellent Mark, you have huge determination, not to mention stamina to stay up all night in freezing weather to do this.
Carole
Really nice Mark. All that effort has paid off.
Well done Mark, you can stay awake when you want to!
Wonderfull image Mark, can't wait to see this once the flats have been applied, you've got so much detail in there!
Can't beat late sessions!
Daniel
:O)
Not bad at all :-) Worth the hypathermia?
or however you spell it?
Just so that I look intelligent....
It is actually hypOthermia!
I'm real jealous- great imaging!
Whatever the spelling, that's a very good result.
But Mark what is it with you and Alnitak ? is that star forever destined to be your nemesis !
Here is version 2:
http://www.markshelley.co.uk/webdisk/horse18102009v2.jpg
I've applied darks & flats. I've only 2x2 binned this (instead of 3x3) because the image can almost take it. Still a bit of vignetting in the corners and still a amp glow splodge in the bottom right. The amp glow is because I took the darks at a different temperature but I think I can adjust the flats to compensate for this (in version 3!).
The diffraction spikes from Alnitak are very annoying but I don't want to surgically remove them.
Mark
Mark, that's looking excellent! I've been waiting for you to post a version of this with flats and darks applied and it hasn't dissapointed.
Every image you post makes me start to re-think my position on buying a CCD camera next year!
Shame about the diffractions spikes, Might be worth doing a mosaic with the flame and getting Alnitak in there to give the spikes context.
Daniel
:O)
Hi,
Alnitak has a very special thing going on, it actually has lines comming across it in blue, John and I noticed it in Les Granges last year. Don't confude these with diffraction spikes err Spagetti Hoops.
Chris
Thanks everyone for your positive comments. I'm certainly very pleased with what the DSLR achieved on this one.
I think there are 3 possible factors that gave improvements over my previous attempts at the Horsehead:
1) As an experiment, I used a CLS filter even though the sky was already relatively dark. This reduced background noise still further.
2) The cold night reduced the thermal noise.
3) I used 10 minute subs instead of 5 minute. Long exposures make sense when the background+thermal noise combined is low.
I will analyse the data in more detail.
But next time I want really excellent seeing as well!
Mark
Final version (I hope!):
http://www.markshelley.co.uk/webdisk/horse18102009v4.jpg
Mark
Lovley pic. Is that a ring nebula towards the top centre?