Go Back   IceInSpace > Images > Deep Space
Register FAQ Calendar Today's Posts Search

Reply
 
Thread Tools Rate Thread
  #1  
Old 09-01-2013, 10:08 AM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
NGC1365 - Sydney

NGC1365 - Backyard Observatory Sydney (North Curl Curl)

TEC140 + IDAS LP + Moravian G2-8300 at -20

LRGB: 150, 50, 50, 50 min all at 1x1 binning: 7 subs (3 x 10 min lum)

I'm feeling fairly happy to get what I did considering light pollution, but wishing I could get smoother looking results in the fainter areas. The luminance data looks quite nice but I probably could have done better collecting colour data at 2x2, or a lot more time at 1x1. Not sure to be honest.

Thanks for looking and comments much appreciated.

Peter
Attached Thumbnails
Click for full-size image (NGC1365 - 1480x1109.jpg)
197.1 KB127 views
Click for full-size image (NGC1365 ver03-final-1471x1006.jpg)
171.3 KB40 views

Last edited by PRejto; 10-01-2013 at 01:36 PM. Reason: Uploaded improved version
Reply With Quote
  #2  
Old 09-01-2013, 10:09 AM
Larryp's Avatar
Larryp (Laurie)
Registered User

Larryp is offline
 
Join Date: Apr 2012
Location: Sydney
Posts: 5,244
That's superb, Peter!
Reply With Quote
  #3  
Old 09-01-2013, 10:12 AM
Poita (Peter)
Registered User

Poita is offline
 
Join Date: Jun 2011
Location: NSW Country
Posts: 3,586
Oh wow, very nice detail.

The background is very black, you may be able to show a bit more of the faint stuff by having the black points set differently.

Way better result than I have managed this year on this target.
Reply With Quote
  #4  
Old 09-01-2013, 10:37 AM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
Thanks Laurie and Peter!

Peter, you are possibly right, though I took care to lower the black point in the final step I tried hard not to clip any black. But, saying that, looking only at the jpeg posted, the green channel is slightly clipped...red/blue are not. But you are right, perhaps the sky is too dark! Thanks.
Reply With Quote
  #5  
Old 09-01-2013, 03:27 PM
alpal's Avatar
alpal
Registered User

alpal is offline
 
Join Date: Jan 2012
Location: Melbourne
Posts: 3,776
Apart from a clipped black point it's a superb image.
Reply With Quote
  #6  
Old 09-01-2013, 04:05 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
Nice work for a shot taken in the city!
Reply With Quote
  #7  
Old 09-01-2013, 04:06 PM
Scorpius51's Avatar
Scorpius51 (John)
Star stuff observer!

Scorpius51 is offline
 
Join Date: Sep 2009
Location: Canberra
Posts: 393
Stunning! Those stars are so sharp, and the colour and detail in NGC1365 is great. Well done!
Reply With Quote
  #8  
Old 09-01-2013, 04:11 PM
CoolhandJo's Avatar
CoolhandJo (Paul)
Registered User

CoolhandJo is offline
 
Join Date: Oct 2008
Location: Sydney
Posts: 1,804
You look to have a very flat field there. Very good colour balance and contrast!
Reply With Quote
  #9  
Old 09-01-2013, 04:44 PM
Stevec35 (Steve)
Registered User

Stevec35 is offline
 
Join Date: Aug 2010
Location: Canberra
Posts: 3,654
Hi Peter

It looks a bit over processed to me with a lot of colour noise present but the detail is very nice. I think extra colour data would definitely fix this as 50 minutes at 1x1 is definitely not enough. Try 50 minutes at 2x2.

Cheers

Steve
Reply With Quote
  #10  
Old 09-01-2013, 04:45 PM
Rigel003's Avatar
Rigel003 (Graeme)
Registered User

Rigel003 is offline
 
Join Date: May 2006
Location: Adelaide, South Australia
Posts: 1,082
Very nice result for a 140mm scope in suburbia. Good detail and colours in the galaxy core and arms. When you lift the background levels you can see a few other small galaxies in the field.
Reply With Quote
  #11  
Old 09-01-2013, 07:52 PM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
Thank you alpal. Rick, John, Paul, and Graeme for your kind words. Much appreciated! Yes, the black is clipped. I will replace the image soon.


Steve, I totally agree with your comments. I normally have collected colour 2x2 but I think I lose detail and I don't get the tight stars I managed with all 1x1....but I've paid a price with not enough colour saturation. Perhaps I will try 2x2 for the galaxy and 1x1 for the stars. I have not ever tried this so I'm sure I can waste many hours! Is there a tutorial anywhere on how one might do this? I can think of two ways I might try...or, is this just a crazy idea?

Peter
Reply With Quote
  #12  
Old 09-01-2013, 08:44 PM
Stevec35 (Steve)
Registered User

Stevec35 is offline
 
Join Date: Aug 2010
Location: Canberra
Posts: 3,654
Quote:
Originally Posted by PRejto View Post
Thank you alpal. Rick, John, Paul, and Graeme for your kind words. Much appreciated! Yes, the black is clipped. I will replace the image soon.


Steve, I totally agree with your comments. I normally have collected colour 2x2 but I think I lose detail and I don't get the tight stars I managed with all 1x1....but I've paid a price with not enough colour saturation. Perhaps I will try 2x2 for the galaxy and 1x1 for the stars. I have not ever tried this so I'm sure I can waste many hours! Is there a tutorial anywhere on how one might do this? I can think of two ways I might try...or, is this just a crazy idea?

Peter
You do theoretically lose a bit of resolution but with the LRGB process it matters less if the colour is binned as long as the luminance is unbinned. Of course just shooting more unbinned colour is another way. One advantage of shooting unbinned colour is that you can add the colour into the luminance to get a bigger signal to noise ratio. Your suggestion sounds most unconventional to me and I can't see how it would work. So I would try both methods and just see how they go. There should be plenty of stuff on the web. Just google LRGB.

You always wind up wasting many hours on this stuff.

Hope this helps

Steve
Reply With Quote
  #13  
Old 09-01-2013, 08:59 PM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
New version. Black point not clipped. Does this look about right for the sky or could it be darker?

I think this version is a bit smoother. I let Noise Ninja work some on the galaxy and not just the background.
Attached Thumbnails
Click for full-size image (NGC1365 ver02-final-1471x1010.jpg)
195.0 KB31 views
Reply With Quote
  #14  
Old 09-01-2013, 10:56 PM
alpal's Avatar
alpal
Registered User

alpal is offline
 
Join Date: Jan 2012
Location: Melbourne
Posts: 3,776
That's looking much better.
Your image is great as it is but
I would add some very fine noise to it now using the info in this link:

http://bf-astro.com/backgndRepair.htm


cheers
Allan
Reply With Quote
  #15  
Old 10-01-2013, 10:48 AM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
Quote:
Originally Posted by alpal View Post
That's looking much better.
Your image is great as it is but
I would add some very fine noise to it now using the info in this link:

http://bf-astro.com/backgndRepair.htm


cheers
Allan
Many thanks Allan!

I will try this technique out for sure. New idea to me, so I appreciate the tip.

Peter
Attached Thumbnails
Click for full-size image (NGC1365 ver03-final-1471x1006.jpg)
171.3 KB17 views

Last edited by PRejto; 10-01-2013 at 01:35 PM. Reason: added version 3 with background fix
Reply With Quote
  #16  
Old 10-01-2013, 05:19 PM
alpal's Avatar
alpal
Registered User

alpal is offline
 
Join Date: Jan 2012
Location: Melbourne
Posts: 3,776
Hi Peter,
That last trick is a clever one to deal with backgrounds.

Another trick but a bit time consuming:
Let's say you have a galaxy and a noisy background.

Make 2 stacks for each of the LRGB:

(1 set ) for the background with everything set to median.

(2nd set ) with everything set to Kappa sigma clipping for the bright areas of the galaxy.

You can then combine the 2 images in layers with Photoshop.
( Put the galaxy on a hide all layer mask & paint it through. )
You'll get a smoother background & sharper details in the brighter galaxy.
Reply With Quote
  #17  
Old 10-01-2013, 05:59 PM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
Quote:
Originally Posted by alpal View Post
Hi Peter,
That last trick is a clever one to deal with backgrounds.

Another trick but a bit time consuming:
Let's say you have a galaxy and a noisy background.

Make 2 stacks for each of the LRGB:

(1 set ) for the background with everything set to median.

(2nd set ) with everything set to Kappa sigma clipping for the bright areas of the galaxy.

You can then combine the 2 images in layers with Photoshop.
( Put the galaxy on a hide all layer mask & paint it through. )
You'll get a smoother background & sharper details in the brighter galaxy.
Thanks Allan! I will try that out for sure!

Peter
Reply With Quote
  #18  
Old 11-01-2013, 08:27 PM
Ross G
Registered User

Ross G is offline
 
Join Date: Apr 2007
Location: Cherrybrook, NSW
Posts: 5,013
Great looking photo Peter, especially coming from Sydney's dirty skies!

Ross.
Reply With Quote
  #19  
Old 12-01-2013, 07:34 PM
PRejto's Avatar
PRejto (Peter)
Registered User

PRejto is offline
 
Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,502
Thanks Ross! I was very lucky the night I collected blue....skys were very clear and steady and I actually got the lowest fwhm values I have yet to see.
Reply With Quote
Reply

Bookmarks


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 01:05 AM.

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