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M27 from Bortle 4 site

Posted: Fri Aug 30, 2019 8:12 pm
by turfpit
Captured at a beach on the Isle of Anglesey, off the North Wales coast. This is a Bortle 4 site as opposed to my home which is Bortle 6.
High res image here https://www.astrobin.com/full/0ffje8/0/

Equipment: Celestron AVX mount, Altair 66ED refractor, Altair 0.8x reducer/flattener, Altair 183C V2.
Capture: 60x60s, 20 darks, 100 bias, 100 flats.
Software: SharpCap 3.2, FITS Liberator (to inspect test frame), Siril (calibration, registration, stacking, crop, colour calibration, green noise removal), Gimp (Curves, Saturation, Contrast).
Capture settings were RAW12, gain 200, black level 30 (black level established by using lowest value which gives centralised histogram for bias frame at gain 200) .

The image from the Bortle 4 site has a much richer star colour and number of stars compared with my Bortle 6 site image here
viewtopic.php?f=16&t=1724. During the registration of frames, Siril was finding in excess of 2,000 stars in the frames.

M27-60x60s.png
M27-60x60s.png (470.32 KiB) Viewed 787 times

The final stack was cropped and re-processed, to show more detail of the nebula:

M27-60x60s-cropped.jpg
M27-60x60s-cropped.jpg (322.42 KiB) Viewed 787 times

Dave

[ALTAIRH183C]
Debayer Preview=On
Output Format=FITS files (*.fits)
Capture Area=5440x3648
Binning=1x1
Pan=0
Tilt=0
Colour Space=RAW12
Fan=On
Temperature=14.3
Black Level=30
USB Speed=1
Auto Exp Target=120
Frame Rate Limit=Maximum
Analogue Gain=200
Exposure=60000
Timestamp Frames=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0.005859375
#MidTone Point
Display MidTone Point=0.015859375
#White Point
Display White Point=0.78515625
TimeStamp=2019-08-28T22:45:31.8468576Z
SharpCapVersion=3.2.6086.0

Re: M27 from Bortle 4 site

Posted: Sat Aug 31, 2019 11:24 pm
by BlackWikkett
NIce image Dave, Well Done!

Re: M27 from Bortle 4 site

Posted: Sun Sep 01, 2019 1:00 am
by turfpit
Thanks Wickett, I think the darker skies made the difference.

Dave

Re: M27 from Bortle 4 site

Posted: Sun Sep 01, 2019 8:49 am
by nexusjeep
Hi Dave,
Nice shot well done, it is an object that I have looked at but never get round to image perhaps get my ass into gear at some point and give it ago problem is so many targets so few clear nights :D

Cheers
Nick

Re: M27 from Bortle 4 site

Posted: Sun Sep 01, 2019 10:26 am
by turfpit
Thanks Nick. Imaging on the beach was rough but worth the effort.

Dave

Re: M27 from Bortle 4 site

Posted: Wed Jan 08, 2020 6:58 pm
by turfpit
A complete re-process of the original data using Astro Pixel Processor. High res image here https://www.astrobin.com/1graw1/0/.
Starting to retain star colours now, which I feel is moving in the right direction.

M27-60x60s-183C-Anglesey-cropped2.jpg
M27-60x60s-183C-Anglesey-cropped2.jpg (337.2 KiB) Viewed 480 times


Looking at the RAW data, I think 90s exposures would be about right.

M27-data.JPG
M27-data.JPG (70.75 KiB) Viewed 480 times


Some Ha to capture more nebulosity wouldn't go amiss. Next time around .......

Dave

Re: M27 from Bortle 4 site

Posted: Wed Jan 08, 2020 8:35 pm
by BlackWikkett
Very nice Dave!

-Chris

Re: M27 from Bortle 4 site

Posted: Wed Jan 08, 2020 11:38 pm
by turfpit
Thanks Chris.

Dave

Re: M27 from Bortle 4 site

Posted: Thu Jan 09, 2020 10:37 am
by umasscrew39
Dave

Excellent star color and shape along with a beautiful M27... congrats. Looks like you found the sweet spot using APP which I have never tried. Awesome image.
Bruce

Re: M27 from Bortle 4 site

Posted: Thu Jan 09, 2020 11:59 am
by turfpit
Thanks Bruce.

I have spent the last 6 weeks grinding through the APP video tutorials repeatedly - especially the ones with downloadable data. I am starting to get to the point where I can repeat the outcome - no gain without pain. Still a long way to go to master the software.

Dave