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Data Usage Reports are available again

We are happy to announce that after a few months of testing, the AAVSO's Data Usage Reports are now available to all observers again.  You may subscribe to these weekly reports by visiting this page:

http://www.aavso.org/apps/email/

Magnitudes: Measuring the Brightness of Stars

On our website, you'll find frequent reference to the term "magnitude" -- this is a unit of measurement of how bright a star looks to us in the sky.  But what does it mean?

The following explanation of what the magnitude measurement scale is and how it was invented is taken from the AAVSO's education project Variable Star Astronomy, Chapter 2:

SN 2011fe

Welcome to the AAVSO's special webpage devoted to SN 2011fe!

Special Notice #236: HST observations scheduled for SDSS074545

March 4, 2011: Further to AAVSO Alert Notice 431, Dr. Paula Szkody, University of Washington, informs us that the time of the HST observations of SDSS074545 has been set for 5:22-9:32 UT on 2011 March 13. This is Saturday night March 12/13. The ground observations to confirm that the object is not in outburst - and allow the HST observations to take place - will then need to take place on Friday, March 11/12.

AAVSO Bulletin 74 for 2011- Letter to Observers

Letter to Users of 2011 Bulletin

                                                                                                                                     February 2011

Dear Observers,

AAVSO BULLETIN 74 -Stars with Double Maxima

In Bulletin 74 there are three stars that exhibit double maxima: V Boo, R Cen, and R Nor. These stars therefore have primary and secondary maxima and minima. They are not included in the main Bulletin table. Their predicted dates of maximum and minimum for January 2011 through February 2012 are presented here in list form (JD and Gregorian calendar dates) and in approximation of the main Bulletin table format.

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