AAVSO: AAVSO Alert Notice 302

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 302 (September 25, 2003)

Subject: Request For Monitoring of Magnetic Cataclysmic Variable 1931-46 QS Tel

Dr. Christopher Mauche, Lawrence Livermore National Laboratory, has requested our assistance in ongoing monitoring, particularly by CCD observers, of the magnetic cataclysmic variable 1931-46 QS Tel (RX J1938.6-4612), beginning now and continuing until at least the end of 2004. QS Tel is a very bright extreme ultraviolet and soft x-ray source likely to be of ongoing interest to researchers, so long-term optical coverage is very important. Because little is known about its optical behavior, this request for optical monitoring represents an opportunity for observers to add to the fundamental information on QS Tel.

Dr. Mauche informs us: "Regular observations are required to (1) establish the optical behavior of QS Tel, and (2) trigger an approved target-of-opportunity Chandra Low Energy Transmission Grating observation, which can take place only when the source is in a high state. The Chandra data will be used to measure the EUV/soft X-ray spectral energy distribution of the accretion-heated white dwarf photosphere and refine the parameters of the absorption lines and edges first detected with the EUVE satellite by Rosen et al. (1996, Monthly Notices Royal Astronomical Society, 280, 1121).

"Snapshot photometry (once per night per observer) is sufficient to meet the needs of this program, although it will be helpful to obtain occasional (~once per month) timeseries photometry for the length of the source's 2 hr 20 min orbital period, especially if its brightness changes significantly."

QS Tel varies between V~15.2 and V~17.4, making it a logical CCD target. Visual observations are also welcomed, but visual observers need to be able comfortably to reach the magnitude range of the star and obtain the positive estimates that are necessary to establish the star's optical behavior. Recent CCD observations by B. Monard, Pretoria, South Africa, show QS Tel to be in its high state, at magnitude 15.6 CR.

AAVSO Chart(s): 'f' scale chart, prepared by Aaron Price, AAVSO Headquarters, which contains both V and R magnitudes for comparison and check stars derived from photometry as described on the chart. The chart for QS Tel may be found at:

Report Object to the AAVSO as: 1931-46 QS TEL; make sure to indicate which comparison and check stars you used.

A webpage on QS Tel will be created on the AAVSO web site (www.aavso.org) that will include an ongoing light curve and other information.

We encourage observers to submit observations via our web site (online data submission tool WebObs), or by email in AAVSO format to observations@aavso.org. If you do not have AAVSO Observer Initials, please contact Headquarters so we may assign them to you. The answering machine at AAVSO Headquarters is on nights and weekends; use our charge-free number (888-802-STAR = 888-802-7827) to report your observations, or report them via fax (617-354-0665).