Forum der Vereinigung der Sternfreunde

Dear colleagues!<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comoffice" />
I assume, some among you are rather less than good informed, regarding the AAVSO photometric campagne of the star P Cyg.
My friend Bernd Hanisch and me published in cooperation with AAVSO a special notice corresponding to this project (see attachment).
This campagne is dedicated for investigation of possible correlations between the photometric V brightness of the star and its spectroscopic Halpha equivalent width.
Particularly for the (photometric) colleagues,
David Williams, Jim Fox, Nick Stoikidis, Bob Crumrine, Kate Hutton
who were not until now involved in spectroscopic investigations of the "spectroscopic amateurs", I would like give a short overview of the project topics and aims:
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The german spectroscopic observers of variable stars Bernd Hanisch and Ernst Pollmann of the german organisation BAV (= Berliner Arbeitsgemeinschaft Veränderliche Sterne) have organizes in co-operation with the AAVSO, a call to monitor the LBV star P Cygni (LBV = luminous blue variable) with high continuity and precision ( ~ 0.05 mag) in its photometrically V brightness. German amateur spectroscopic observers monitor P Cygni since 14 years. They could develop together with data of other european observers a overview of the longterm behavior of the Halpha emission (see attachment). The current development phase of the star - the S-Doradus-phase - lead since years to high fluctuations of the Halpha equivalent width (EW), which were measured so far by the group in very impressive manner. The professional astronomy recommends measurements of the photometric V brightness simultaneously to EW measurements for continuation of investigations of N. Markova et al. (A&A 376, 898-906, 2001). Markova found long-term variabilities of 7.4 years and 600 days in the sense of positive correlation between the photometric V brightness and the Halpha EW.

The observation program is temporally unlimited and should motivate as much as possible particularly amateur astronomers to take part at this campagne. A view in the AAVSO database shows, there are fortunately the first variable star observers who make currently their first V measurements available.
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I am very interested in your opinion.......and in case of any question you are welcome !!
Best wishes,
Ernst