Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Celestron RASA 11" back from collimation

  • Please log in to reply
3 replies to this topic

#1 pyrasanth

pyrasanth

    Vanguard

  • *****
  • topic starter
  • Posts: 2,206
  • Joined: 08 Jan 2016

Posted 08 December 2019 - 02:42 PM

Some of you may remember that I sent my RASA back to Celestron UK to be collimated. It had quite a bad tilt that manifested in half of the stars on a full frame sensor being out of focus and looking like little donuts.

 

I received the OTA back on Friday so spent yesterday setting everything backup. The weather co-operated for just under an hour tonight and I was able to focus manually (the focus was way out and took the best part of 10 minutes to wind back in by hand with the precision focuser fitted). I need to reattach the electronic focuser which will allow far tighter stars but I managed a reasonable job by eye. I noticed that M52 has been captured in the same frame as well as NGC 7538 to the right of the image. I really can't wait for a fine night to test a few hundred subs on this region of the sky. I see in the top right a really nice band of nebulousness coming into view. This looks like a great imaging area for the RASA on a dark night. 

 

However I could tell that a good job had been done as the field came into focus with myriads of even little donuts. I captured about 100 test frames from both the double cluster and the bubble nebula so I had some material to evaluate. The image of the bubble nebula is 27 15 second subs on the QHY168C camera and IDAS filter. I was surprised at the amount of detail captured for a total of less than 7 minutes. The image has minimal processing only DBE, SCNR & a masked stretch. The moon was also quite bright which could not have helped with lots of moving cloud. I have shown the full frame of the QHY168C.

 

I've also attached the collimation result from CCD inspector. David Hinds did a good job on the collimation and I now feel I have an instrument that I can thoroughly enjoy moving forward.

 

Clear skies to you all!

 

Best wishes

Mark

 

NEWCOLLIMATION_WEB.jpg

 

Bubble_WEB.jpg


Edited by pyrasanth, 08 December 2019 - 03:27 PM.

  • PrestonE, icee_stars, dswtan and 10 others like this

#2 hungerford

hungerford

    Viking 1

  • -----
  • Posts: 748
  • Joined: 23 Aug 2008

Posted 09 December 2019 - 04:13 AM

Superb result. 



#3 sharkmelley

sharkmelley

    Mercury-Atlas

  • *****
  • Posts: 2,690
  • Joined: 19 Feb 2013

Posted 09 December 2019 - 08:42 AM

Assuming the scope is now accurately collimated, which there's no reason to doubt, the CCDInspector plot suggests to me your sensor or adaptor might have a tilt left to right.

 

Mark


Edited by sharkmelley, 09 December 2019 - 09:30 AM.


#4 pyrasanth

pyrasanth

    Vanguard

  • *****
  • topic starter
  • Posts: 2,206
  • Joined: 08 Jan 2016

Posted 09 December 2019 - 10:11 AM

Assuming the scope is now accurately collimated, which there's no reason to doubt, the CCDInspector plot suggests to me your sensor or adaptor might have a tilt left to right.

 

Mark

The Baader UFC adapter is held together by dovetails & screws. I will check these over the weekend. However I need to produce a new CCD inspector output as last night was a bit rushed so the samples presented to CCD inspector were perhaps not optimal.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics