Probleme RMS avec Alpy600

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Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: Probleme RMS avec Alpy600

Post by Peter Somogyi »

Robin and Etienne,

When pressing "Go" in calibration assistant (UV enabled as usual), I get nonsense RMS for setting these "Pixel size" values (like 16 or 30): 6.25, 6.3, 6.6.

Calculating the value by the formula from http://www.astrosurf.com/buil/isis/guid ... ration.htm I get this (ISIS-V5.7.0):

dx = 989 (h-alpha pixel X coord) - 505 (H-beta)= 484

the forumla of "p = 3123 / dx" giving me this: 6.4524793388429752066115702479339

Which is roundedly to 2 digits, it is 6.45, back from where I started.
Copy/pasting this value accurately with all digits doesn't improve anything my calibration (remains everything the same).

So there is no conclusion on my side.
But, never thought the ATIK 414 or Alpy may have different designs (wondering in what way).

Cheers,
Peter
Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: Probleme RMS avec Alpy600

Post by Peter Somogyi »

"J'ai l'impression qu'il y a comme des interférences, le flux oscille sur la longueur du spectr et il n'est pas uniforme"

Etienne,

I do see like a few % ripples of roughtly 50A in low res too (Atik 414 + Alpy) - I'm correcting it via good SNR response star -, but not this type of error.
I'd rather suspect either your flat /(dark/bias?) is wrong, or the "Instr. responsitivity" box got autofilled when tried 'Response Assistant' by accident.

- Peter
Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: Probleme RMS avec Alpy600

Post by Peter Somogyi »

Let me attach my ref.stars from this weekend (similar ATIK 414 + Alpy 600), reduced with flat,dark,bias but no IR curve (intendedly - to show really no such kind of ripple):
ref_stars.zip
G Per, The Cas
(37.53 KiB) Downloaded 300 times
'The Cas' is a bit more complex, but dividing by Pickles A7V giving finer slope with noises/resolution difference caused ripples.

Perhaps your wav. calibration difference to your instrumental spectrum might be a cause for such a cutouts.

HTH,
Peter
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