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iot Cyg Be star?

PostPosted: Fri Aug 11, 2017 3:41 pm
by Francois Teyssier
I use iot Cyg (A5V V =3,8) as reference star for CH Cyg

Comparison of Ha profile with HD 11636 (CFLIB in ISIS database)

iotCyg.PNG (30.07 KiB) Viewed 7169 times

A faint double emission appears clearly in the core of the line
It is already present in a spectrum obtained in 2016, December

Confirmation spectra are welcome


PS: don't forget CH Cyg in the vicinity, this is the main purpose ;)

Re: iot Cyg Be star?

PostPosted: Sat Aug 12, 2017 12:47 am
by Christian Buil
Une spectre de iota Cyg fait à l'arrache cette nuit (pose courte en même temps que remontage de la manip OHP, mise en station, réglage spectro, etc) :


La même chose en retirant les raies telluriques :


Je suis victime d'un joli phénomène de franges (ici en utilisant une Atik414EX). Celui-ci perturbe le profil, mais à part cela, je ne note pas une émission significative de la raie Halpha. (le profil est peut être élargie (émoussé) par un v sin i élevé). Ton spectre Francois est pas mal bruité en fait, ceci explique peut être cela à ce stade (il est fait avec quel setup ?).


Re: iot Cyg Be star?

PostPosted: Sat Aug 12, 2017 6:17 am
by Francois Teyssier

SC 14" + Echelle + 460EX bin 2
Le continuum au niveau de Ha est ~ 4000-5000


Re: iot Cyg Be star?

PostPosted: Sat Aug 12, 2017 7:22 am
by Peter Somogyi
I also noticed what Francois shows - without emission -, but at least an emerging level:
2017_0226_0715.png (12.5 KiB) Viewed 7136 times

OFF: Christian, I've played last year lot with the ATIK 414 + LHires III.
The internal flat is highly reproducible (same values per wavelength - even after 1 year), just the spectrum not :) (ripples shifted by like a +/- 0.3A, varying depending on the spectrum Y position but their amplitude also don't match)
External flat is better (ripples amplitudes much better match), but need a nearby good (Vega) to shift the ripples to a good position. Or just use that star to fix the ripples (taking out from flat, as flat ripples still shifted).
What is sure, don't use the flat in the usual way, need the ripples image decomposed and shifted (and maybe multiplied).
EDIT: I've even wrote a sine .fits generator in C (using libfitsio), the sine function perfectly matches, just the amplitudes modulated in some random way.

- Peter

EDIT#2: before anybody asks, my spec. on 2017.07.15 got unusually good by SNR: min ADU (H-alpha) = 1670, max ADU (continuum) = 2941, ATIK 428 EXm, bin2x2, exptime=60 seconds. (FHWM by eye should be like a 4 pixel)

Re: iot Cyg Be star?

PostPosted: Sat Aug 12, 2017 9:18 am
by Joan Guarro Flo
Bonjour Christian,

Similar ripples, (perhaps their origin, are not the same as those of your ATIK414EX), also left me in areas of the graphs where the signal was smooth, for example, around the H6678 of the DEL SCO. This effect has also been seen in some other echelles, I can not specify which ones.

The solution, was to put another diffuser in front of the Tungsten light, (two frosted glasses of the support part of a microscope holder).

In the image, in red the undulations in a graph of the Linx, (now the problem is already solved), In blue, in the Mussol, the undulations have disappeared.

The CCD is an ATIX460EX.

Cordialement, Joan.