The study of southern W UMa stars has by and large been neglected. It is only recently that headway into period and physical parameter study has been made by the All Sky Automated Survey- ASAS, and the re-analysis of previous observations of candidates by Kreiner, Jerzy M.; Kim, Chun-Hwey; Nha, Il-Seong (2001).
With time on institutional telescopes at a premium contributions by amateurs with moderately sophisticated equipment in the southern hemisphere could be invaluable to this end. As an example of the successful deployment of small telescopes - ASAS detection of eclipsing binaries from Las Campanas Observatory was done with a 7 cm telescope aperture, a focal length of 20 cm and a 2K x 2K CCD camera from Apogee. More information about ASAS is available on the WWW. (Paczynski etal 2006) ASAS Home page
Apart from selfish motives, (I am collecting data on southern W UMa candidates for my MSc and ultimately PhD), southern observers could establish a 24 hour continual observation on particular candidates similar to that set up by Joe Patterson at the Centre for Backyard Astrophysics. Observational data would be made available to your organisation, AAVSO and emailed through to me in text file. The format of this would be discussed with interested parties.
Contributions from amateurs would be cited in any publications written on the particular targets.
I am willing and excited about setting up an observation project of this kind. Ultimately we would establish a web-site with relevant contributors listed as well as aims and objectives of the study. Along with the website, participants would be given appropriate targets for observation in an email, perhaps once monthly from myself.
We would be looking at W UMa candidates that have not been studied for long time spans as well as newly detected W UMa variables. Very few of the EW southern stars in the GCVS have had any study apart from very elementary period determination.
The objectives apart from period analysis; that is determining initial periods; and from longer time span studies, slow down/speed up rates; also include accurate determination of physical parameters of the system by modelling. Physical parameters include mass ratios, limb darkening, gravity coefficients, radial velocities, fill out values of the Roche lobe etc. The latter parameters are made using different versions of the Wilson Devinney code from observations in white light, spectroscopic studies (once basic periods have been determined) and filtered observations in UBVRI.
Any contributions would be welcome. Your members could send white light or filtered observations.
Any interested parties are welcome to contact me at this email address. Christopher Middleton
See also Newsletter no 3 which also contains further information about the project and who to contact. A brief description about this type of variable is also included in the newsletter.