This seems to be the season for revisiting old favourites and I make no apology for redirecting observers' attention to this one.
Here is an excerpt from a letter just received from the AAVSO, with an introduction by Jan Hers, Director of the ASSA's Variable Star Section:
Jan writes: [The AAVSO request] goes a long way to correct the erroneous idea that some have, viz. that visual observers of variable stars spend their time making the same old observations of the same old stars, which will then be tucked away in soon-forgotten ledgers for the possible, probably unlikely use of a posterity which really could not care less about them.
How wrong they are!
Please read the following notes about the forthcoming campaign to observe EX Hya carefully. Your observations, especially if you live in a relatively cloudless region, are urgently needed.
Jan Hers
From: AAVSO aavso@aavso.org
Subject: AAVSO Alert Notice 272
Date: 13 March 2000 10:26
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
INTERNET: aavso@aavso.org
Tel. 617-354-0484 Fax 617-354-0665
AAVSO ALERT NOTICE 272 (March 13, 2000)
1247-28 EX HYDRAE - MULTIWAVELENGTH OBSERVING CAMPAIGN SCHEDULED
Astronomers at the Planetary Science Institute in Tucson, Arizona have scheduled an international multiwavelength observing campaign on the cataclysmic variable EX Hya from May 5 through June 10. Our assistance has been requested to provide close visual coverage during the satellite campaign in order to help correlate the observations obtained from x-ray to infrared by the different satellites.
EX Hya is an intermediate polar, which is an interacting binary subtype of cataclysmic variable (CV). It is the only CV to show emission lines in the extreme ultraviolet (EUV) spectral region when not in outburst. The astronomers inform us that they have obtained observing time with the EUVE satellite between May 5 and June 10, which will be the longest single observation ever performed by the satellite on a star. When they observe EX Hya with the EUVE, the astronomers will be able to make the first-ever detailed observations of plasma diagnostics in any source other than hot-star chromospheres such as Capella's. They report that extending EUV plasma observations to other systems and at other wavelengths is a crucial test of models and has applications spanning hot stars, neutron star binaries, and AGNs.
Thus, good optical coverage during the observing interval is essential to the success of this program. Please monitor EX Hya very closely from now through the end of June, and especially closely between May 5 and June 10. Observations made every 5 minutes for as long as possible every clear night would be very valuable. Please record the time of your observations to three decimal places and report your observations of EX Hya to AAVSO Headquarters so we may keep the astronomers informed of its status.
For observers who have access to CCD, we strongly recommend CCD observations every 5 minutes for as long as possible. If you can carry out BVRI CCD observations, please contact AAVSO HQ for information on the BVRI comparison star magnitudes.
Your participation is essential to the success of this ground-breaking observing campaign!
Janet A Mattei, Director
Elizabeth O Waagen, Senior Technical
Assistant
So here we have it, straight from the horses mouth, how amateurs with their modest telescopes can complement the work that the professionals do with their multimillion dollar hardware.
Have a look at the "Canopus" 1999 August article for more details but use the chart in this issue.
Danie Overbeek.
Tel 011 453 6918
danieo@global.co.za