October 19, 2007: Dr. Paula Szkody (University of Washington) has requested our help in monitoring the cataclysmic variable SDSS074545 (SDSS J074531.92+453829.5) for upcoming Hubble Space Telescope observations. The HST observations are scheduled to be made during the week of 2007 October 29 -- November 03 UT. Dr. Szkody requests monitoring of this object during the two weeks prior to the observing window, and intensive monitoring during the 24-48 hour period during which observations will be made. An AAVSO Special Notice will be issued when HST ground controllers inform us the observing window is officially open.
SDSS074545 (0738+45) is at R.A. 07:45:31.92 , Dec +45:38:29.5 (J2000)
SDSS074545 is a cataclysmic variable not previously seen in outburst, and is being observed as part of a larger study of pulsating white dwarf primaries in cataclysmic variables. In particular, Szkody and collaborators are investigating the effects that higher temperatures and larger rotation velocities caused by accretion have on the pulsation behavior.
This object is very faint at quiescence, with V=19.1. AAVSO observations are requested to ensure that the object is indeed faint when observed with HST, as it could damage the instrument if it were to go into outburst. AAVSO observations will be used to make a "go"/"no go" decision when the observing window opens, and will also be used in the analysis of the resulting data.
Observers are asked to monitor SDSS074545 nightly beginning immediately (2007 October 19 UT). Visual observers please observe asnormal, and report any "fainter than" estimates using the faintest comparison star magnitude you can reach if unable to detect SDSS074545 itself. CCD observers are asked to use filters during observations if available; V filter is preferred, but B,Rc, and Ic may also be used. Detection of the variable itself is not required unless you can reach V=19 in reasonable time, but please use sufficient exposure to detect at least the V=15.8 comparison star (AUID 000-BCY-392; RA 07:45:35.45 Dec +45:38:47.6) with a S/N of 10 and report the observation as a "fainter-than" measure.
Beginning 2007 October 29 UT, please observe this object as often as possible for the duration of the week using the observing procedure outlined above, and submit data as soon as is possible via WebObs. In the event of an outburst, please contact the AAVSO immediately.
A charts for SDSS074545 are available at this URL:
For more information on this campaign, visit the following URL:
This campaign is being organized at AAVSO HQ by Dr. Matthew Templeton.
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