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The new BAV MAGAZINE SPECTROSCOPY
Dear colleagues!
The international growing interest within the field of the amateur research of Variable Stars in astronomical spectroscopy, did lead in close co-operation with the BAV executive committee to a publication organ titled “BAV MAGAZINE SPECTROSCOPY” (BAV = Bundesdeutsche Arbeitsgemeinschaft Veränderliche Sterne). This English / German online magazine is available now in its first edition as free of charge download under:
http://www.bav-astro.eu/index.php/veroeffentlichungen/bav-magazine-spectrocopy/issues-of-magazine
Ernst Pollmann
Hi Ernst,
Congratulations, nice presentation, reads smoothly! Important “to the point” scientific information for the amateur!
Your article on page 24 concerning P Cygni is a nice example of how the VV Cep campaign philosophy can evolve especially for the correction of the H-alpha line fluxes in respect to the M star continuum. Therefore we need of course photometry data of an eligible standard star.
Keep up this excellent magazine!
Will it stay free downloadable in the future?
Success!
Kind regards,
Marc.
P.S. Suggestion on the article on page 8: fig.3 instead of “erlaubte” simply “Energieübergänge” to avoid misinterpretations.
Hi Marc,
It is indeed possible to perform absolute flux calibration of spectra using photometric magnitude measurements as a reference (as opposed to just calibrating the spectra relative to the continuum). It is a technique frequently used by amateurs these days to calibrate broad band (typically low resolution) spectra where an absolute flux calibration is required. The details of the method were developed on the ARAS forum. Tools were built into ISIS software and the procedure was formalised by BAA member here, David Boyd.
http://www.spectro-aras.com/forum/viewtopic.php?f=8&t=897
and has been used in several of his (peer reviewed) papers in the BAA Journal.
It is not strictly valid to use the technique in the way Ernst has done here however as the spectral range covered is not the same as that of the V filter passband The implicit assumption here is that the flux in the V band and in the continuum at H alpha are linearly correlated. This is not always the case and would need to be established, for example by performing simultaneous photometry in V and R bands.
Alternatively more conventional techniques for absolute flux calibration of spectra are also used by amateurs by recording spectra of spectrophotometric standard stars, aided for example by the use of dual width “spectrophotometric” slits available for the Shelyak spectrographs which allow the total flux to be collected. This does need stable atmospheric conditions however during the observation. (analagous to all sky photometry). Again ISIS software has the tools to enable this.
http://www.spectro-aras.com/forum/viewtopic.php?f=8&t=695
Cheers
Robin
The link given took me to the publication which had had been written in either the German or English language. I take it then that there is not a fully English version. Unfortunately, I can get by in Italian,but not German.
The more pro-am type publications the better and I wish you success.
Eric
Congratulations on the new magazine Ernst. Great to have another spectroscopy publication!
Eric, you can try translating it with Google Translate. Type ‘Translate’ into Google. Follow the link and upload the document. Then select German to English. You’ll find you need to switch back and forth between the Google translation and the pdf as the table and figures are missing from the translation.
Best wishes,
Andy
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