NGC7822 - First image of the season!

[gorann]

Finally last night the sky cleared, the moon was below the horizon and there was 6-7 hours of astro-darkness up here. So here is the first data I have captured this season.

Gear: ES 127ED apo, Canon 60Da, EQ8 mount. 31 x 8 min, so 4.1 hours. Stacked in Nebulosity 4 and prosessed in PS CS5

I also had my Samyang 135 f/2 with a Canon 70D side by side (hopefully 100+ good 1 min exposures). Will have a look at that data later today (when I may be exposing again, weather permitting)

All comments and suggestions most welcome!

Cheers

 

[wimvb]

Nice first image. How was seeing? The brighter stars seem rather soft.

[gorann]

1 hour ago, wimvb said:

Nice first image. How was seeing? The brighter stars seem rather soft.

Thanks Wim,

SQM was 21.1 so rather dark (I can get down to 21.5) but there may have been a bit of water in the air due to all the recent raining, but I did not notice it. (Is there a good way to measure seeing?) Those brighter stars are actually quite bright so I had to work to keep them down, so that may also be a reason. Moreover, the object was very close to zenit so my EQ8 had to struggle more than usual with guiding. RMS around 1.5" before meridian flip and around 0.7" after, and there was a small but noticeable effect on star size after the flip.

By the way, I have been experimenting with a processing technique in PS called APF-R. Here is what it looks like after I have run it through that one. Not sure if it is any better. What do you think?

[wimvb]

I'm not sure, but I believe that seeing is determined by measuring FWHM of the stars (not the brightest, those are over exposed) in arcseconds. Of course, you have to take guiding into account. Best is to do a short unguided image. Otoh, if the guiding FWHM was only 0.7" after the flip, this shouldn't contribute much to the seeing FWHM.

I prefer the first image. The stars seem to be a little bit tighter and have less of a halo. There is an overall brightness difference between the images. There's also a slight increase in the weak Ha signal in the second image. I think that you can safely increase the black point at the very end of your process to boost contrast a little more.

[Barry-Wilson]

Very nice Goran and it must be very satisfying to get back to imaging after your bright northern summer.

[gorann]

20 minutes ago, Barry-Wilson said:

Very nice Goran and it must be very satisfying to get back to imaging after your bright northern summer.

Thanks Barry,

yes it really is. In many ways more satisfying than working on Liverpool Telescope data of course. The big worry was as usual to remember the procedures and find all the bits and pieces that I had put away in clever places. The only mishap was not my fault. While doing the star and polar alignments I suddenly I lost power to the mount. It turned out that the power inlet in the EQ8 had somehow got lose and I had to unscrew a plate on the mount to fix it. Need to make a more permanent fix. Chinese manufacturing....

[gorann]

2 hours ago, wimvb said:

I'm not sure, but I believe that seeing is determined by measuring FWHM of the stars (not the brightest, those are over exposed) in arcseconds. Of course, you have to take guiding into account. Best is to do a short unguided image. Otoh, if the guiding FWHM was only 0.7" after the flip, this shouldn't contribute much to the seeing FWHM.

I prefer the first image. The stars seem to be a little bit tighter and have less of a halo. There is an overall brightness difference between the images. There's also a slight increase in the weak Ha signal in the second image. I think that you can safely increase the black point at the very end of your process to boost contrast a little more.

Yes, Wim, the stars were better on the first one and it could be a bit darker so I selectively combined them and worked a bit on the curves. Think this may be the best so far...

[wimvb]

After rain and seemingly perpetual cloud, it cleare up tonight after nine. Too late to get my scope from the shed and set it all up.

It's a good thing you have an obsy, Göran. I hope you get to do some imaging tonight.

[gorann]

24 minutes ago, wimvb said:

After rain and seemingly perpetual cloud, it cleare up tonight after nine. Too late to get my scope from the shed and set it all up.

It's a good thing you have an obsy, Göran. I hope you get to do some imaging tonight.

Right now at 2300 it is a complete cloud cover but the weather report (yr.no) indicates that it may clear up around 0100, and from experience (framing, PHD2, possible trouble shooting), that would get me exposing at 0200 and only get me about 2 hours, and since I do not trust the weather report and only slept 3 hours this morning, and have some work to do on Monday, I am really tempted to go to bed.... And I still have the Samyang data from yesterday to process: about 200 one-min frames so my Nebulosity is working hard and slow

And, the season has just started!

[Allinthehead]

Nice image Gorann. I feel your pain re the sleep situation. Stupid work ruining our fun.

[gorann]

23 hours ago, Allinthehead said:

Nice image Gorann. I feel your pain re the sleep situation. Stupid work ruining our fun.

Thanks!

Hopefully it remained cloudy all night

I had another go at the image, using high-pass filter to bring out the pillars a bit better (not that easy in RGB images for some reason) and I also did some star maintenance.

Cheers

 

[Uranium235]

Great image! Let us know how you get on with the 135mm data, I did exactly the same as you - but I think I only got about 40 images @ 180s each (havent had a go a processing it yet).

[gorann]

Thanks Rob!

Did you also go for the same object or just had the Samyang sitting beside? In any case here its the Samyang result- Cannot say I am too enthusiastic about it. The lens is obviously doing a great job with pin-point stars all to the corners and my flats were just that - flat. So no vignetting with an APS-C, and I did not use them. However, I may have picked the wrong target (so many stars and so small area of nebulosity) and it is odd processing an image with so much under-sampling (6.6"/pixel if I got it right). What helped a bit at the end was the "Lighten only DSO and Dimmer Stars" Noel's action for PS. Well, here it is anyhow, in the final two versions (so far). About 100 x 1 min subs at ISO 1600:

[Freddie]

Nice image and interesting to see the evolution over the various versions you have posted.

[MikeODay]

Lovely images Goran - I love the colours and the wonderful detail.  

[gorann]

On 9/19/2017 at 14:35, mike005 said:

Lovely images Goran - I love the colours and the wonderful detail.  

Much appreciated Mike!

 

On 9/19/2017 at 13:50, Freddie said:

Nice image and interesting to see the evolution over the various versions you have posted.

Thanks Freddie! Yes, there has been an evolution, as always, but this evening there was almost a revolution when I started looking for dust around and found plenty of it. So here is version 35.

 

 

 

 

[wimvb]

I like this latest (last?) one. The widefield images showed that there is a lot more Ha in this area, and you managed to bring that out in v 35.

[gorann]

24 minutes ago, wimvb said:

I like this latest (last?) one. The widefield images showed that there is a lot more Ha in this area, and you managed to bring that out in v 35.

Thanks Wim,

Yes, the latest version but unlikely to be the definitive one. I am probably like most people in this game. As long as I do not get new data to keep me busy, I cannot help looking at my old images and suddenly thinking, humm, what would it look like if I......

[gorann]

This may be my last post of this image. I am now quite embarrassed by my first posted version and I can only blame my enthusiasm for pulling the posting trigger too soon on having acquired my first own data from my obsy this season, after 5 months of non-astro-darkness up here. Just finding all the bits and pieces and trying to remember how to run the Windows programs on the obsy computer (being a dedicated Mac person) was a bit of a worry.  I am now more pleased with it than of possibly any other image over my short (2 year) AP career, and look forward to more clear nights, although none are in sight right now....