[Dr Andrew Smith]

ISIS only scales the darks if the exposures are mismatched so as long as you used matched exposures it’s not a problem.

Regards Andrew

[Dr Andrew Smith]

I will see if I can find it again.

Regards Andrew 

[Dr Andrew Smith]

It is best not to use scaled darks with CMOS cameras as there is some evidence that amp glow is non linear although consistent. 

Regards Andrew 

[Dr Andrew Smith]

There are a few threads on SGL Stargazers Lounge on the topic that might help you Eric.

Regards Andrew 

[Dr Andrew Smith]

In any event I found their discription of how the did the Spectrophotometry interesting.

Regards Andrew 

[Dr Andrew Smith]

Strange indeed Robin, and suprising as the are both experts on red supergiants. Indeed EML has written a book on the astrophysics of Red Giants!

Maybe the IR bands are more sensitive to Teff than in the V . I will look at her book and see if I can find any comment on it.It will be interesting to see how the discussion develops.

Regards Andrew 

[Dr Andrew Smith]

An interesting paper from Emily Levesque and Phil Massey https://arxiv.org/abs/2002.10463 who propose ” …that episodic mass loss and an increase in the amount of large-grain circumstellar dust along our sightline to Betelgeuse is the most likely explanation for its recent photometric evolution”

Regards Andrew

[Dr Andrew Smith]

Hi Paul, yes they work well. You might want to try this http://www.njnoordhoek.com/?p=660 I have not tried this version but used an earlier one. It is an old link so I am not sure if it still works.

Regards Andrew

[Dr Andrew Smith]

I take nearly 2000 10s slitless images a night and currently very few show a satellite or meteor trail. I hope it stays like that.

Regards Andrew 

[Dr Andrew Smith]

I think what you see is very much determined by your environment and culture. I can’t “see” the classical constellations. I see geometric  figures, straight lines, circles etc. Haveing had the arrow pointed out it now seems obvious.

Regards Andrew 

[Dr Andrew Smith]

Nice spectra and congratulations on the award. Well deserved for Star Analysers and your unstinting support for budding spectrocopists. 

Regards Andrew 

[Dr Andrew Smith]

I was beginning to think it was me!

Regards Andrew 

[Dr Andrew Smith]

Noble of you to lay bare your private thoughts. I think I have a jinx with the web site.

Regards Andrew 

[Dr Andrew Smith]

Did you get my mail via baa. Beginning to look like it’s just me!

I got your second mail.

Regards Andrew 

[Dr Andrew Smith]

I got your message and one from Robin Leadbeater last night. I had asked for a copy maybe that is the issue. I will try sending you one without doing that.

Regards Andrew 

[Dr Andrew Smith]

Well done Robin. Did you miss posting the image? 

Regards Andrew 

[Dr Andrew Smith]

I have a copy of sky atlas 2000 you can have for free if you let me have your address.

Regards Andrew 

[Dr Andrew Smith]

Thanks could be very useful. Regards Andrew 

[Dr Andrew Smith]

Nice one Robin – Regards Andrew

[Dr Andrew Smith]

Derek, can you draw a diagram if what you think is going on? I can’t  follow the verbal description. 

Regards Andrew 

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