My first spectrum WR133

[Nacho Novalbos]

Good evening all spectroscopists!!

Finally, after a year dedicated to getting to know and configuring the equipment, training in the methodology of guidance, acquisition and reduction of spectra with ISIS.... At last, I can show my first "serious" spectrum.
This is the spectrum of WR133 (HD190918) obtained from Barcelona. There are 7 x300 sec images in binx1, obtained with the DADOS 200l/mm grating and an Atik16HR attached to a little (but powerful... ) Mak127 f/11.8
The spectrum is calibrated in wavelength using the method proposed for C. Buil for LISA, that is, a Neon spectrum for the red part calibration (Many thanks to Alain and the group "the Nice People" for their help in the construction of the calibration module) and an A2V reference star (HD192640) to calibrate the blue part.

It would be an honour to know your opinion about the result and how it could be improved.

As a curiosity to say... to get ISIS to do the calibration job correctly (correctly placing the Balmer lines in the reference spectrum) I follow the Christian's advice in the ISIS manual. I had to slightly modify the "official" 6.45 microns ccd pixel size to 6.37 microns.

Cheers!!!

[Robin Leadbeater]

Hi Nacho,

It looks pretty good to me. Perhaps the continuum is a bit steep at the blue end? Christian Buil has a spectrum of WR133 which you can download and compare with on his website here
http://www.astrosurf.com/buil/survey/wr ... stars.html

I have a page here with some tips on getting a good relative flux calibration (response correction)
http://www.threehillsobservatory.co.uk/ ... opy_21.htm

Cheers
Robin

[Nacho Novalbos]

Hello again.

Robin, thank you very much for your comments and for the link to your document with which I have been able to clarify much more the concept and methodology to get a good flux calibration (relative) in my spectra.
I have also reprocessed my WR 133 spectrum (20220711) and as you recommended compared them to the C.Buil spectrum. At first glance it seems that the coincidence between them is quite good. Althoug, as you pointed out in your post, the flux intensity of my spectrum in the blue zone of the continuum seems to be high. I observe the same tendence for my other WR 133 spectrum adquired on date 20220724.



In your document I have read that the slit must be in the same direction of the atmospheric dispersión, but in both cases I have taken out the spectra with the slit parallel to the horizon instead of perpendicular...
Do you think the effect on the continuum may be due to this?...
Or maybe is due to have a lot of bad flat-fields?...
Anyway I have already changed the DADOS position, aligning the slit perpendicular to the horizon, and the tungsten lamp position in to the calibration module. I hope to see how my results improve...

One thing that I find curious is that my two WR 133 spectra coincide practically 100% with Christian's spectrum, except in the N(II)6548.05- H-H(II)6583.39 zone, where I seem to observe some blue shift in the spectrum 20220724 with respect to the others.



Thank you very much for your help and your comments.