M51 (B & W)

[JohnH]

I took this image with a view to creating a Luminance layer. There is a horrible crescent artefact on the right hand side which MAY be caused by the full moon about 60 degrees away. I am not sure, my flat images have not got rid of a dust shadow either. I created a masterdark the next morning (when I did my flats) and there was horrible artefact, as if light was leaking in.

I took 40 subframes at 90 seconds (L) and discarded 15 because of satellite trails. I have used the image stack to practice with PI. It is quite possible that I might just start again with longer subframes and a lot less moon.

It is nice to see that I have at least 4 other galaxies showing up as well.



Taken 6th May with SharpStar 15028 on iOptron CEM25P. ZWO ASI 1600 MM Pro (-20 Celsius).

I am trying to learn patience. (And I am looking forward to the time some large nebulae heave into my viewing space)

Regards,

John

[ApophisAstros]

John , Using sigma stacking should take your satelite trails out as it recognises that its different from other frames, wont help with the artifact though if its in all farmes.I have also read recently that there is no need to go lower than -15oC as the benefits dont improve past that, its just labours the camera unnecessarily.
Re the artifact found this but only one piece of advise.
https://www.cloudynights.com/topic/588637-odd-crescent-artifacts-in-images/
HTH
Roger

[JohnH]

Thanks Roger, that is useful to know.

There is a reducer in the SharpStar but it is a fairly essential element. I am going to need to work around the  problem for a while.

Regards,

John

[Roberto]

Great result and FOV John - well done! 

Roberto

[NoelC]

Nice work John, M51 is looking cool!
Your field of view is massive isn't it.

Noel

[Carole]

Really coming on John.

Carole

[The Thing]

Hi John,

I have a Sharpstar 61EDPH refractor with reducer and its a very well made bit of kit. I would look at filters, filter wheel, OAG if using one, for any internal surfaces that are even vaguely reflective. I went over the inside on my T extensions and the above mentioned with black Krylon paint and it made a noticeable difference. I have a bottle of Black 3 to use next time, it's about as black as the stuff they use in space cameras and scopes.

HTH

Duncan

[JohnH]

Thanks Duncan,

I shall have a close look and see if there is anything obvious. In retrospect, I was probably set up too close to the house and it's lights. We have a small garden with limited viewing angles and I need to see to the north for PA.

Regards,

John

[MarkS]

That widefield view definitely puts the galaxy in context!

Mark