#1  
Old 24-02-2012, 09:41 AM
rmuhlack's Avatar
rmuhlack (Richard)
Professional Nerd

rmuhlack is offline
 
Join Date: Nov 2011
Location: Strathalbyn, SA
Posts: 979
Rosette Nebula

Last night's efforts, and my first decent go with a guided exposure. Took a chance and went for 8 min subs.

Turned out that PHD lost the guide star 5 sub exposures from the end of the program (and I wasn't watching it constantly to notice...) so i was left with 13 x 8min subs. Rejected 2 subs in the stacking process with DSS, and then tweaked the curves in Darktable to give the resulting image.

My camera mod has moved the focal plane forward slightly, and so now i think im getting some slight coma in the corners even with my MPCC. Not sure how I can correct this (as i'd need to move the CC closer to the camera body, and its already flush with the t-ring) - guess in due course i'll just need to move to a cooled CCD

With an ambient temp of ~22C there looks to be a fair bit of noise as well, so maybe 8min subs is pushing it a little at this time of year with my un-cooled DSLR. Need to get thinking about that cooling mod...

So in the end:

11 x 8min subs @ISO800
20 darks
5 flats (I took more but they were twilight flats and i was too slow in between each shot and the sky illumination changed)
20 dark flats

comments, advice appreciated

Edit: larger image available here: http://astrobin.com/5884/
Attached Thumbnails
Click for full-size image (rosette1_01.jpg)
127.5 KB57 views

Last edited by rmuhlack; 24-02-2012 at 11:30 AM. Reason: to include link
Reply With Quote
  #2  
Old 24-02-2012, 11:30 AM
scagman's Avatar
scagman (John)
Registered User

scagman is offline
 
Join Date: Apr 2011
Location: Kinglake West
Posts: 717
Hi Richard, That looks good, nice colors. Pity about the guide star.
Reply With Quote
  #3  
Old 24-02-2012, 01:05 PM
orion58's Avatar
orion58 (Bruce)
Registered User

orion58 is offline
 
Join Date: Nov 2011
Location: Southern Wisconsin, USA
Posts: 4
Very nice image - good job...
Reply With Quote
  #4  
Old 24-02-2012, 02:19 PM
rmuhlack's Avatar
rmuhlack (Richard)
Professional Nerd

rmuhlack is offline
 
Join Date: Nov 2011
Location: Strathalbyn, SA
Posts: 979
thanks

Another thought I just had is whether the slight elongation could be due to colimation error (particularly re the secondary?). It could be my imagination, but the issue seems more pronounced in the top left and bottom right, rather than the other diagonal corners. Is this astigmatism from a secondary, or something else
Reply With Quote
  #5  
Old 24-02-2012, 02:39 PM
peter_4059's Avatar
peter_4059 (Peter)
Big Scopes are Cool

peter_4059 is offline
 
Join Date: Jun 2007
Location: SE Tasmania
Posts: 4,574
Nice Rosette Richard. The elongation in two of the might be tilt. I had it in one corner and squaring the focuser up seemed to improve things.
Reply With Quote
  #6  
Old 24-02-2012, 05:42 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,079
Nice shot. Got some Ha on this one last night and hope to complement tonight to smooth things out.
Reply With Quote
  #7  
Old 24-02-2012, 10:43 PM
Visionoz's Avatar
Visionoz (Bill)
Registered User

Visionoz is offline
 
Join Date: Oct 2008
Location: Perth, Western Australia
Posts: 717
Not bad at all Richard! - own mods + imaging the Rosette

I've been in this since 2009 and still haven't imaged the Rosette yet!

Cheers
Bill
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 04:29 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement