M51 Whirlpool Galaxy

[tooth_dr]

The whirlpool galaxy

I only managed to get luminance data the other night due to power supply issues with my second camera.  This is 63 x 300s luminance with a QHY9 mono.   There was a weird artefact on all the images, that didnt stack out, nor did it move relative to the stars (it was in the same place in every frame relative to the borders of the chip)

 

So as you do, I did the best I could and searched the forum for my old image of M51.  I found an uploaded JPEG I took 10 years ago using a 10" with a Canon 300d, and set about manually combining the data, and here is the result!

 

 

Thank for looking!

 

Adam

 

[coatesg]

Nice job. The weird artifact is flare, or a rogue reflection from a bright star (guessing one of the stars in the Plough). The only way to eliminate it is to flock or baffle appropriately and stop the light from reflecting off whatever is causing it....

[tooth_dr]

7 minutes ago, coatesg said:

Nice job. The weird artifact is flare, or a rogue reflection from a bright star (guessing one of the stars in the Plough). The only way to eliminate it is to flock or baffle appropriately and stop the light from reflecting off whatever is causing it....

Thanks Graeme.  I had a suspicion it was flare, its the first time I've encountered it.  Is it normal for it not to move even though I dithered all my frames?

[coatesg]

4 minutes ago, tooth_dr said:

Thanks Graeme.  I had a suspicion it was flare, its the first time I've encountered it.  Is it normal for it not to move even though I dithered all my frames?

Yeah - you'd need to dither it a lot (way more than a few pixels) for the flare to go away. It's one of the hardest things to track down sometimes - incident reflections and glad can happen when you're quite some way from the star that causes it!

[tooth_dr]

5 minutes ago, coatesg said:

Yeah - you'd need to dither it a lot (way more than a few pixels) for the flare to go away. It's one of the hardest things to track down sometimes - incident reflections and glad can happen when you're quite some way from the star that causes it!

Thanks for the explanation ????

[FaDG]

I agree with @coatesg, seems to me a reflection coming from an off-axis star, probably Alkaid. 

I had a similar issue with my 72ED some months ago, with a strong reflection when imaging M42. 

I cured it by day, removing the camera and pointing the scope towards a light bulb (squinted, as I knew that the reflection came from outside the FOV). 

And there it was, whack! Not the lens, nor the dew shield, the stock tube was already perfectly flocked and baffled, but an adapter (from the 54mm focuser to 48mm) was shining like a torch! 

So I scratched it thoroughly with sandpaper, then painted it matt Black, and the flare was all but gone! 

So, off you go, trying to detect what's so shiny inside your imaging train, and best of luck! 

Fabio

 

 

[FaDG]

9 minutes ago, coatesg said:

you'd need to dither it a lot (way more than a few pixels) for the flare to go away

Sorry to say that dithering won't solve that. 

It's so large because it's coming from so far out of the FOV, you should move the star half the screen away ti see any difference. 

Instead, try to understand what is reflecting like crazy.

[tooth_dr]

Thanks guys. I’m still happy with this despite the flares. 

[FaDG]

5 minutes ago, tooth_dr said:

Thanks guys. I’m still happy with this despite the flares. 

You may well be! 

It's a great photo. What scope did you use? 

BTW, I found a picture I took when looking for the cause of the reflection. Here you are, you might look for something like this, if you wish to sort it out in the future. Should be pretty clear what the issue was. 

[Craney]

Coincidentally...there is another current post that might be relevant to the discussion above....

https://stargazerslounge.com/topic/333888-the-blackest-black-paint-black-30/

Opening up image trains to track down a reflection makes me feel slightly queasy.   Maybe try a longer dew shield and use it as a light shield.

The colour combo shot looks good, and to think it is 10 years apart in time.  Wow!

[FaDG]

23 minutes ago, Craney said:

Opening up image trains to track down a reflection makes me feel slightly queasy.  

Well, in my case the guilty adapter was between the helical focuser and the flattener, so I didn't have to hack the tube to pieces. ?

[peter shah]

Love the colour rendition, detail is lovely. Shame about the reflections hopefully you'll get to the bottom of the issue.. 

[Knight of Clear Skies]

14 hours ago, tooth_dr said:

So as you do, I did the best I could and searched the forum for my old image of M51.  I found an uploaded JPEG I took 10 years ago using a 10" with a Canon 300d, and set about manually combining the data, and here is the result!

Nice bit of improvisation, well worth the effort.

[tooth_dr]

19 hours ago, Craney said:

Coincidentally...there is another current post that might be relevant to the discussion above....

https://stargazerslounge.com/topic/333888-the-blackest-black-paint-black-30/

Opening up image trains to track down a reflection makes me feel slightly queasy.   Maybe try a longer dew shield and use it as a light shield.

The colour combo shot looks good, and to think it is 10 years apart in time.  Wow!

Thanks Sean.  Hard to believe 10 years apart indeed.  I did have a 7 year sabbatical between then and now though 

[Seanelly]

That nifty combination turned out great. I'm really looking forward to having a crack at this subject.

[tooth_dr]

2 minutes ago, Seanelly said:

That nifty combination turned out great. I'm really looking forward to having a crack at this subject.

Thanks Sean.  I should have had colour on the same night but my other camera was messing about. 

[astro mick]

Perfection is,nt always needed Adam.

Thats a great result.

Mick.