Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Jul 13, 2014, 21:35:27

Title: Eagle Nebula
Post by: MarkS on Jul 13, 2014, 21:35:27
Eagle Nebula taken the nights of 30 June and 1 July.

Taken with modified Canon 550D on Celestron C11 with TS 0.8 reducer and IDAS LPS-D1 filter.  The best 12 subs (5 minutes each) of 42 were chosen for this stack because guiding problems caused the others to have significiant elongation in R.A.

This is the Red channel only from those 12 subs since the stars in the Green and Blue channels were far more bloated and also didn't line up very well with the Red.  If I had known this in advance I would have used an Ha narrowband filter instead to improve the S/N ratio.

So this image has been well and truly snatched fom the jaws of defeat.

(http://www.markshelley.co.uk/Astronomy/2014/eagle_red_01072014_small.jpg)

Larger version here:
http://www.markshelley.co.uk/Astronomy/2014/eagle_red_01072014.jpg

When I get time, I might try to rescue a full colour image fom the data.

Mark
Title: Re: Eagle Nebula
Post by: Carole on Jul 13, 2014, 22:01:15
That's very good for just the red channel Mark. 

Carole
Title: Re: Eagle Nebula
Post by: MarkS on Jul 13, 2014, 22:38:30
The sky quality was pretty good near the horizon on those two nights and the seeing wasn't bad either.

Mark
Title: Re: Eagle Nebula
Post by: RobertM on Jul 13, 2014, 23:27:09
I think that's quite good considering it's only 60 mins on a DSLR.  A narrowband filter would have given you tighter stars and a bit more resolution in the nebula.

Robert
Title: Re: Eagle Nebula
Post by: Mac on Jul 14, 2014, 03:35:11
Very nice.

Mac.
Title: Re: Eagle Nebula
Post by: ApophisAstros on Jul 14, 2014, 07:53:41
is that "the pillars of creation" ?? :undecided:
Title: Re: Eagle Nebula
Post by: JohnP on Jul 14, 2014, 09:03:36
Nice Image Mark :-) What guiding probs you having - I thought now you had your permanent set etc. guiding would be less of an issue?
Title: Re: Eagle Nebula
Post by: Carole on Jul 14, 2014, 10:26:54
Quoteis that "the pillars of creation" ??
correct, the Eagle shape in the middle.

Carole
Title: Re: Eagle Nebula
Post by: MarkS on Jul 14, 2014, 20:45:42
Quote from: JohnP
Nice Image Mark :-) What guiding probs you having - I thought now you had your permanent set etc. guiding would be less of an issue?

The thing is that the Eagle is low down in the sky (max 25deg altitude) so the seeing becomes a bigger issue.  I no longer guide in Dec so when the seeing deteriorated the stars elongated more in R.A. than they did in Dec.  The 12 good subs (6 from each night) had guiding errors of around 0.7arcsec RMS in both R.A. and Dec but that deteriorated to around 1.3 arcsec in R.A. and 1.0 in Dec which caused quite obvious egg-shaped stars.

The EQ6 really isn't suited to long focal length imaging at low altitudes even with my belt mod.  I'm eagerly awaiting my 48:12 pulleys so I do proper PEC - I'm hoping that will really help.

Mark