When the hot tub strikes back...

[AMcD]

Life is full of compromises.  The quid pro quo for my spending time and money automating my observatory during lockdown was agreement to the installation in the garden of a wood fired hot tub from Sweden. 

For the past number of clear nights, I have been gathering hours of data on the Pac Man Nebula.  Imagine my dismay when I finally got round to examining the integrations (yes, I should have checked earlier) and found this...

After scratching my head for a number of days as to what the rather prominent artefact at bottom left could be, I finally identified the culprit.  As the full moon has been rising it has been reflected beautifully in the chrome chimney of the bloody hot tub...

As can be seen from the warm orange glow on the scope, I already have to contend with an old sodium streetlight that shines directly onto the observatory and which the council stubbornly refuse to convert to something downlit and LED 😠

Interestingly, the artefact only appears when the scope is at a certain orientation to the smokestack of the hot tub.  I have now moved to shooting the Iris Nebula in LRGB and the artefact has gone...

The moral of the story is: don't put the hot tub next to the observatory... 😂.  The next question is whether I can process out the artefact from my hours of data?

[wimvb]

To paraphrase Mick Jagger:

"I see a bright tube

And I want it painted black.

No r'flections anymore

I want them to turn black."

[AMcD]

37 minutes ago, wimvb said:

I want it painted black

That is going to require a considerable amount of negotiation with my better half 🤭

[Paul M]

That there is what's known as a First World Problem!

Once upon a while ago we had a hot tub, It was the MD's idea but she got bored soon. I took to it like a fish to a hot tub. Loved sitting there with a gin on a cold frosty night watching the stars.

Sublime...  

[Captain Scarlet]

I can see an easy solution. Flock the chimney tube! Not the way flock tape normally likes to bend but I’m sure it can be persuaded! 😁

Magnus

[AMcD]

17 minutes ago, Captain Scarlet said:

Not the way flock tape normally likes to bend

The smokestack gets unbelievably hot.  I think the flock tape would bend whether it liked it or not - right before it caught fire 😂

[Xsubmariner]

 I would be concerned about any debris that might be scattered over the observatory from the chimney.  I have fitted exhaust pipe tape in the past, which could be wrapped around the chimney without risk of fire.

Edited December 10, 2022 by Xsubmariner

[tomato]

If you use StarXTerminator or something similar, that should leave an image with the nebulosity and the glare artefact. It should then be possible to carefully clone out most of the artefact.

Could you paint the stack with automotive exhaust paint? You would need to remove the highly polished finish first.

[AMcD]

The optimism displayed by you both @Xsubmariner and @tomato regarding my negotiating powers is most kind, but entirely misplaced😂.  I suspect the shiny chrome of the stack is going to be declared off limits DIY wise.  

I have in mind a tall matt black board that can be mounted on the outside of the observatory to screen the stack on those few moonlit nights when I image at the particular orientation that results in the artefact.

[wimvb]

5 hours ago, AMcD said:

I have in mind a tall matt black board that can be mounted on the outside of the observatory to screen the stack on those few moonlit nights when I image at the particular orientation that results in the artefact

Why not a tube or a sleeve that you slide over the chimney?

[sharkmelley]

Relax, I'm pretty certain this is not caused by the hot tub chimney! 

Instead, it is more likely an artifact generated by the bright star Schedar, outside the field of view.

Alnitak, near the Horsehead, is another star that typically causes this type of problem.

Mark

Edited December 11, 2022 by sharkmelley

[AMcD]

1 hour ago, sharkmelley said:

Relax, I'm pretty certain this is not caused by the hot tub chimney!

Many thanks @sharkmelley, my wife will be delighted!  No chance though of wrapping Schedar in exhaust tape or slapping on some exhaust paint 😂  I think @wimvb nice idea of a shroud is also out.

[Pompey Monkey]

3 hours ago, sharkmelley said:

Relax, I'm pretty certain this is not caused by the hot tub chimney! 

Instead, it is more likely an artifact generated by the bright star Schedar, outside the field of view.

Alnitak, near the Horsehead, is another star that typically causes this type of problem.

Mark

I concur with @sharkmelly

If it was the chimmey stack, the artefact would move in relation to the sensor as the scope tracked and would largely be rejected in the integration process. As the pattern is well defined and looks like a bright star artefact,  I also conclude that is what it is.

[ollypenrice]

On 11/12/2022 at 10:45, sharkmelley said:

Relax, I'm pretty certain this is not caused by the hot tub chimney! 

Instead, it is more likely an artifact generated by the bright star Schedar, outside the field of view.

Alnitak, near the Horsehead, is another star that typically causes this type of problem.

Mark

Agreed. The fix for this kind of 'out of shot beam' is to finish the shoot and then aim the scope more towards the source of the problem (let's say Schedar in this case) and try another shoot. Obviously the new shoot has to cover the problem area but I've always found it was possible to find a scope position which covered the problem area with a problem-free 'patch.' You don't need a full depth of integration to make a workable patch but you do need to be able to register it to the original. Lots of programs now allow this but in the past it was Registar or nothing.

If AMcD doesn't have such software I'll be happy to do it on my copy of Registar. PM me.

Olly

PS If you want to blacken the stack, use stove paint. Being pigment-based it is non reflective outside the visible spectrum and this is vital for astro-blackening.

Edited December 12, 2022 by ollypenrice
PS

[AMcD]

On 12/12/2022 at 17:42, ollypenrice said:

Agreed. The fix for this kind of 'out of shot beam' is to finish the shoot and then aim the scope more towards the source of the problem (let's say Schedar in this case) and try another shoot.

Cracking tip Olly, thank you.  I have a copy of Registar, and other software that can register.  I will give it a try.