April 22, 2013: Further to AAVSO Alert Notice 471 (http://www.aavso.org/aavso-alert-notice-471), HST/COS is scheduled to observe the eclipsing WZ Sge-type cataclysmic variable QZ Lib:
QZ Lib 2013 Apr 26 14:37:44 through 21:23:30 UT
The HST team will be making a final decision on observing QZ Lib based on the observations of April 24/25, and observations from the following night will also be essential. Close monitoring of QZ Lib through April 27 is requested to be sure it is below the threshold brightness and to have a good magnitude value for correlation with the HST observations. QZ Lib is V=17.5 at minimum and can be as bright as V=11.5 at maximum.
After QZ Lib, the next target will be the eclipsing dwarf nova SDSS J154453.60+255348.8:
SDSS J154453.60+255348.8 2013 May 1 04:06:20 through 08:17:24 UT
Giving QZ Lib highest priority, please begin covering SDSS J154453.60+255348.8 now; close monitoring through May 2 is essential. The most recent data on this system, from Gordon Myers of Hillsborough, CA, Stuart Littlefair of Sheffield, England, and Arto Oksanen of Muurame, Finland, suggest that an outburst may be beginning. Dr. Boris Gaensicke reports that reasonably frequent outbursts occur and offers a light curve (CRTS light curve <http://nesssi.cacr.caltech.edu/catalina/20010319/103191230504100327p.html>). SDSS J154453.60+255348.8 is V=<18 at minimum and can be as bright as V=15.7 at maximum.
As instructed in AAVSO Alert Notice 471, for CCD observers, simultaneous photometry [shortly before, during, and after the HST observations] would be ideal. For the magnitude estimates, a nightly V measurement from now through the HST observations and a day beyond would be best. If positive visual observations are possible, they are welcome, as are visual fainter-than observations fainter than magnitude 15.0.
Coordinates (2000.0)
QZ Lib R.A. 15 36 15.97 Dec. -08 39 07.68
SDSS J154453.60+255348.8 R.A. 15 44 53.60 Dec. +25 53 48.9
Charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp).
Please report observations as soon as possible to the AAVSO International Database using the names QZ LIB and SDSS J154453.60+255348.8, respectively. If an outburst is detected, please report observations immediately. Many thanks!
This AAVSO Special Notice was compiled by Elizabeth O. Waagen.
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