High latitude summer astrophotography

[IDM]

Hi all,

I am looking for thoughts and advice based on this image of the Leo Triplet that I took on the 4^th of May.  The equipment was an Esprit 100 with flattener (brand new present to me), UV/IR filter and Zwo ASI294 MC-Pro mounted on an EQ6R.  

I live just outside of Newcastle upon Tyne which is 54.97 North, so we currently only get proper darkness between 01.00 and 02.00, indeed using Sharpcap it is now hard to get polar aligned much before 22.00. Despite this the image attached is 60 1 minute subs taken between 22.30 and 23.30. What I don’t like is the speckled noise in the dark parts of the image. The noise may well be my lack of skill in processing, but, I wondered if it might be due to natural skyglow from the sun still illuminating parts of the sky. If so would some form of filter help, either UHC or CLS or possibly Optolong L-Pro? The filter will be used with an OSC. The issue of lack of darkness is only going to get worse through the summer!

I do have an Optolong  L-Extreme filter which I have used very successfully for nebula, however, this filter does cut light emission so much I am unsure if it will help in my situation. Also from what I understand the filter is much less suitable for Galaxies, though looking at Astrobin some people seem to use them on galaxies. Again I would be very grateful for any thoughts and experiences.  

I have read so much about light pollution filters, much if which indicating that they do not help, but most of the comments have been with regard to human-made light pollution, I am interested in possible help at sites where the issue is due to the sun (my sky is mostly bortle 5, though worse pointing East towards the city of Newcastle upon Tyne).      

[alacant]

13 minutes ago, IDM said:

I don’t like is the speckled noise in the dark parts of the image

Hi

For only 1 hour, very good.

The best way to lose the noise would be to take frames only when its dark and take loads more of them. Dither between frames and stack using a clipping algorithm.

Or -and we don't recommend this-  just denoise it:

Cheers and HTH.

 

 

[IDM]

6 minutes ago, alacant said:

Dither between frames and stack using a clipping algorithm.

Or -and we don't recommend this-  just denoise it:

I haven't tried dithering yet and will also explore different ways of stacking. Also what program did you use to denoise the image, I couldn't get any improvement and would like to know what you did?

Also from your comments I am thinking you don't think filters will help?

 

Thanks

Ian

[alacant]

1 hour ago, IDM said:

program did you use to denoise

StarTools, but we'd recommend using it -or any other denoise algorithm- ONLY as a last resort, and even then, sparingly. Far better to control the noise by having more data. 

1 hour ago, IDM said:

you don't think filters will help

For this target, no. You need all the light you can get.

[Jerry Barnes]

I have Topaz Denoise, I dont use for astro much though.  I tried it on your image and it wasnt that effective and I think Alacant's advice is good, take a few more hours of images.

[IDM]

2 hours ago, Jerry Barnes said:

I have Topaz Denoise, I dont use for astro much though.  I tried it on your image and it wasnt that effective

I have the evaluation version and also tried it on the image and couldn't get anything like the improvement that Alcant achieved with StarTools. Whilst de-noise is not recommended the difference between the algorithms is very interesting.

I will have to try and get more time on the targets, but what with the lack of darkness through the summer this is going to become very difficult. I can see me having to put things away until the planets start to turn up later in the year, which is a real shame.

Ian

[Clarkey]

Take the summer off😁. That's what I do. It is the last day of astro darkness here tonight.😭

Solar imaging?

[DaveS]

Narrow band can be done during nautical dark.

Edit: Globs are also viable targets,, some are very bright, so run lots of short subs to avoid excessive background.

Edited May 8, 2022 by DaveS

[tomato]

You can image DSOs in Nautical darkness, but you do need lots of integration time. This is 6 hrs on the Leo Triplet taken with an Esprit 150/IMX 571 OSC, about 40% of the subs were taken in Nautical darkness.

For comparison this is 4 hrs of subs with an Esprit 150/ASI 178 LRGB, all taken in Nautical darkness.