In AAVSO Bulletin 75 there are two stars that exhibit double maxima: 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 2012 through February 2013 are presented here in list form (JD and Gregorian calendar dates) and in approximation of the main Bulletin table format.
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/
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 is the brightest supernova as seen from Earth in nearly 20 years. It's a rare event that astronomers around the world are excited about -- it's not only a beautiful spectacle, it may also teach us new things about supernovae and the universe that we live in. Here you'll find information on what SN 2011fe is, why astronomers around the world are watching it, and most importantly, how you can make your own observations and help create a scientific record of this supernova!
The late Bob Nelson developed over 5800 O-C (Observed - Computed) files for eclipsing binaries, all in Excel format, which we are hosting on our site. The purpose of this database is to provide information on period variation for selected eclipsing binaries (for astronomers interested in a particular star), as well as to determine the best elements for predicting future eclipses. These elements go into eclipse prediction software, like at Shawn Dvorak's site (Bob and others help provide updated elements for Shawn).
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.
Letter to Users of 2011 Bulletin
February 2011
Dear Observers,
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.
AAVSO Bulletin 74 - Predicted Dates of Maxima and Minima of Long Period Variables for 2011 - is published in a new format. The information that was included in earlier numbers of the Bulletin is included in this new format, along with more information. This year the Bulletin does not include stars that do not have an AAVSO mean curve.
