P Cyg

[Marco Leonardi]

Hi,
this is my spectra made with L200 spectroscope.

spectra.jpg (2.61 KiB) Viewed 10091 times

and the profile (ISIS):

_pcyg_20121029_935_mleonardi.png (2.99 KiB) Viewed 10091 times

This is a wonderful object.

Thanks,
Marco

[Ernst Pollmann]

Hi Marco,
today I saw your really good spectrum of the star.
It would be great, if you could take part at the project campaign (if you are interested).
Would you be so friendly, to evaluate the Halpha-equivalent width!
I want use your spectrum for the campaign.

Best wishes,
Ernst

[Marco Leonardi]

Hi Ernst,
yes it will be a big pleasure for me to partecipate at p Cyg campaign. Recently I installed a new grating: 1800 lines/mm (the previous spectra has been made at 600 lines/mm).

Here below please find yesterday night p Cyg spectra with 1800 lines/mmm grating and the EW at H alpha calculated by ISIS.

_pcyg_20121210_847_mleonardi.png (4.44 KiB) Viewed 10012 times

EW.gif (34.67 KiB) Viewed 10012 times

Let me know if you want also the absorption line EW near H alpha.

Thanks and Regards,
Marco

[Marco Leonardi]

Sorry to push this up.
I am kindly asking to someone here if he/she can explain to me in what wavelength range I should measure the EW of H alpha p Cyg. I read the previous posts but I am confused with the different terminology. Probably for this campaign an EW Halpha measure method has been agreed and defined.
Thanks and Regards,
Marco

[Martin Dubs]

Hello Marco,

Markova http://adsabs.harvard.edu/abs/2001A%26A...366..935M estimate the EW between 6510 and 6617 A, which includes the wings. Ernst Pollmann makes reference to this paper on his campaign site (see: http://astrospectroscopy.de/), but I do not know if this range is the adopted value for the present campaign. In my opinion the range for the determination of EW should always be given in order to eliminate misunderstandings. Francois Teyssier used a similar range (6515 to 6615 A).

Regards,

Martin

[Marco Leonardi]

Thanks Martin ! Very kind.

So finally I measured the EW using SpcAudace.

I calculated it in the range between 6510 6617 A as per Markova doc.

For my p Cyg spectra profile name is:

_pcyg_20121210_847_mleonardi

SpcAudace command is:

spc_autoew _pcyg_20121210_847_mleonardi 6510 6617

The result is the following:

# Date: 2012-12-10T20:19:48
# JD: 2456272.347
# EW(107.0=6510.0-6617.0)=-88.71 A.
# Sigma(EW)=10.57 A.
# SNR=23.

The value of EW of - 88.71 A seems in the same magnitude of Francois Teyssier data.

I hope the method I used is the correct one for this campaign.

I wonder if all observators are using the same software (SpcAudace) or others.

Thanks and Regards,
Marco

[Marco Leonardi]

I have normalized the file using SpcAudace and then I made the EW with the following softwares and using always the same lambda range 6510 6617.

Results:

ISIS: -90.73 A using the FWHM command

VSpec: -95.00 A using console and leq 6510 6617 command

SpcAudace: -89.78 A using command spc_ew _pcyg_20121210_847_mleonardi_norm 6510 6617

SpcAudace: -89.78 A using command spc_ew _pcyg_20121210_847_mleonardi_norm 6510 6617 6

SpcAudace: -97.27 A using command spc_ew _pcyg_20121210_847_mleonardi_norm 6510 6617 15

In SpcAudace please note the 6 or 15 digit. This number is related with the continuum extraction method.

Just to share.

Regards,
Marco

[Christian Buil]

Into ISIS the spectrum continuum need to be normalized to unity before EW calculation.

I prefer separate the two operations (continuum normalization and EW (latest by using FWHM function)) because normalization quality is very critical.
I use first the "Continuum" function for a high quality continuum fit, then only, I compute EW. Of course, during the fit, you have to exclude
the Halpha line (the extension limit of the line is some empirical here... the important point is the use of same spctral range for a reproductible result on the time).

Christian

[Robin Leadbeater]

I think for this sort of project I would take non normalised spectra from the different observers and do the normalisation and EW measurements the same way using the same software. I suspect this might reduce the variability significantly.

Cheers
Robin