Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Rocket Pooch on Feb 22, 2009, 20:40:11

Title: Horse Head Ha
Post by: Rocket Pooch on Feb 22, 2009, 20:40:11
With Atik 314L ZS66 & F.67 reducer, imaging at 260mm approx F4, the field in not flat hence the coma.

(http://farm4.static.flickr.com/3638/3300669165_128356f221_b.jpg)
Title: Re: Horse Head Ha
Post by: JohnP on Feb 22, 2009, 20:49:40
Nice FOV & you got the background curtain very well..

Looks more noisey than I expected (not used to seeing you publish noisey images... :-) ) What was total integration - I know you had to cut this short which is a shame...

John
Title: Re: Horse Head Ha
Post by: Rocket Pooch on Feb 22, 2009, 21:04:59
Yes it was 5x10 minutes could really have done with 12-16 subs, never mind, maybe next week?
Title: Re: Horse Head Ha
Post by: Fay on Feb 22, 2009, 21:05:32
That is extremely nice Chris, well in focus, lovely curtains
Title: Re: Horse Head Ha
Post by: JohnP on Feb 22, 2009, 23:04:40
only 50mins - explains it - great result on a very dim object..
Title: Re: Horse Head Ha
Post by: MarkS on Feb 23, 2009, 06:07:42

The curtaining and especially the tendrils are coming out well and there is plenty of other detail appearing - what a pain that you didn't get all the subs you wanted to get the noise down.

Mark
Title: Re: Horse Head Ha
Post by: RobertM on Feb 23, 2009, 08:32:06
Another excellent capture and what a FOV!   I know John mentioned noise but it looks quite subdued in the faint areas to me and not entirely surprising for only 50 minutes.  Like the focus and the pinpoint stars, what technique do you use to achieve that ?

From the images I've seen the sky must have been pretty good on Saturday.
Title: Re: Horse Head Ha
Post by: Mike on Feb 23, 2009, 15:34:06
Very nice Chris. But why is it the wrong way around?
Title: Re: Horse Head Ha
Post by: Rocket Pooch on Feb 24, 2009, 14:50:52
Hi,

The focus was done using Focus in AstroArt it gave FWHM of 1.2 x 1.4 approx for one of the stars in the FOV, very stable skies.

Mike, is it backwards, I never really look?

Chris
Title: Re: Horse Head Ha
Post by: MarkS on Feb 24, 2009, 16:47:45
Quote from: Space Dog
The focus was done using Focus in AstroArt it gave FWHM of 1.2 x 1.4 approx for one of the stars in the FOV, very stable skies.

Is that 1.2 x 1.4 pixels, arcseconds or what?  I'll check my M81 image to estimate my own FWHM.

Mark
Title: Re: Horse Head Ha
Post by: JohnP on Feb 24, 2009, 18:35:43
Yes - image is normally presented with flame to left - then again strictly speaking it needs to be rotated through 90 deg... Horsehead is almost directly below Alnitak...

Title: Re: Horse Head Ha
Post by: Tony G on Feb 24, 2009, 22:32:51
Hi Chris,

Another great image and with so little effort, the scopes and mount just fall out of the motor, and hey presto, an image, mine fall out and they require collimation and gaffer tape.

Anyway well done.

Tony G

PS Is this one of your missing frames.   ;)

(http://farm4.static.flickr.com/3642/3307758600_bab961a98f_m.jpg)

 

 
Title: Re: Horse Head Ha
Post by: MarkS on Feb 25, 2009, 08:20:06
The FWHM of the stars in my subs was approx 4 pixels i.e. approx 3 arcsec.  That sounds a bit high to me but this star bloating is made up of 3 effects:
1) Seeing
2) Guiding deviations
3) De-focusing
4) Bayer pixel averaging on the colour CCD - this will bloat stars slightly

Quantifying each effect might be difficult ...

Mark