NGC7822 Mosaic in NB

[symmetal]

Taken over two and a bit nights at the beginning of the month this is a two panel mosaic taken with a RASA 11 v2 and ASI6200MM camera on an EQ8. Conditions weren't great with a haze visible below about 30 degrees elevation, so there is a bit more than normal flaring on some stars. I had to discard many frames where it was too bad, so this is around 60 to 90 min per filter per panel.

Binned 2x2 and processed in PI and PS. Mixed SHO and Foraxx palette used. I actually did no background extraction, as efforts with ABE and DBE made it look worse, so I'm pleased with how it turned out. PhotoMetricMosaic did a good job on blending the panels.

It was going to be a three panel mosaic to include Sh 2-170, the 'Little Rosette Nebula' which forms the dot of the question mark, but after four hours of hazy images I gave up and had to leave it out.

Central crop

Just creeping into frame at the top is a planetary nebula labelled as PN A66 1 in Aladin's Simbad

Towards the top right of open cluster NGC7762 is another unnamed cluster centred between two bright yellow and blue stars. Above this is a star 'with blue horns'.

Aladin has the star labelled as V* V712 Cep, a long period variable, but no horns are visible near it. A mystery. 🤔

Alan

[tooth_dr]

Great write up Alan.  This shows that apeture is definitely king, there is some detail in the centre crop.  I always like to look for the little birdie  

[JonHigh]

That is a seriously great image! Perhaps I should invest in Pixinsight rather than using Siril? But that’s for another post. 😂👍🏻

Edited October 20, 2023 by JonHigh

[glafnazur]

Great image Alan, I zoomed into the image as far as I could (500x ) to see if there were any more weird objects and I found a few more stars with 'horns'. There weren't many but interestingly they all appear on red/orange stars.

These were on the right hand size of the image

  

and these were on the left hand side

  

I must say your focus must be near perfect as I zoomed in to 500x and the stars still have great shapes, I found this cute little cluster of different colours that made me smile. 

 

 

Edited October 21, 2023 by glafnazur
Typo

[symmetal]

19 hours ago, tooth_dr said:

Great write up Alan.  This shows that apeture is definitely king, there is some detail in the centre crop.  I always like to look for the little birdie  

Thanks Adam. 😊 Binning the image using IntegerResample in PI helps greatly with the noise such that 1 hour total exposure is really all that's needed for NB, especially Ha. I only bin it to keep the image size down and to stop PI moaning that the 'resulting image will be very big. Do you wish to continue?', especially with mosaics. 🙂 A full frame sensor still gives a big image even when binned.

There was a report on CN showing that binning in the camera with CMOS cameras gives significantly softer images than using software binning later.

I'm surprised that the RASA 11 doesn't seem to show any significant gradients on any filter, even when a partial Moon is around. My FLT98 images always had small gradients even on moonless nights. 

Yes, the bird is aiming for its parent star, responsible for its existence. 😉

[symmetal]

19 hours ago, JonHigh said:

That is a seriously great image! Perhaps I should invest in Pixinsight rather than using Siril? But that’s for another post. 😂👍🏻

Thanks very much. 😊 I put off getting Pixinsight for many years, but gave in when BlurXTerminator was released, and once you follow some tutorial videos, its way of working is not so strange. 🙂

Alan

[symmetal]

5 hours ago, glafnazur said:

Great image Alan, I zoomed into the image as far as I could (500x ) to see if there were any more weird objects and I found a few more stars with 'horns'. There weren't many but interestingly they all appear on red/orange stars.

Thanks glafnazur. 😊 You spent a lot of time checking for other 'horned' stars and it looks to be just an optical effect at the frame edges. Pity. Most odd that it's only reddish stars giving this blue effect though. I'll check my other images to see if they also show this. Maybe it's the hazy conditions that have shown it up.

Yes, I'm very impressed with the edge star shapes with the RASA 11 especially with a full frame sensor. Once you've got the tilt/spacing set up, which is rather critical.

Alan