Alert Notice 361: Request to monitor SDSS091908 for HST Observations

November 7, 2007: Dr. Paula Szkody (University of Washington) and collaborators have requested our help in monitoring the cataclysmic variable SDSS091908 (SDSS J091945.11+085710.0) for upcoming Hubble Space Telescope observations. The HST observations are scheduled to be made on or about the afternoon of 2007 November 14 (UT).  Dr. Szkody requests monitoring of this object beginning immediately (2007 November 07 UT), and intensive monitoring during the 24-48 hour period surrounding the scheduled time of observations.  HST observations are tentatively scheduled to begin 2007 November 14, 18:25 UT (JD 2454419.2674).

SDSS091908 (AAVSO Designation 0914+09) is located at RA 09:19:45.11 , Dec +08:57:10.0 (J2000)

SDSS091908 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 faint at quiescence, with V=18.3.  AAVSO observations are requested to ensure that the object remains in quiescence 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 at 09:46 UT on November 14 (JD 2454418.9069), and will also be used in the analysis of the resulting data.  Due to the fact that this object is currently a morning object and the requirement that confirming observations be submitted by 2007 November 14, 09:46 UT, observers in Europe, Asia, and Oceania are strongly encouraged to participate in this campaign.  Observation planners at STScI must have confirming observations within the 12 hours preceeding the decision time.  HST Observations are currently scheduled to begin around 2007 November 14, 18:25 UT (JD 2454419.2674).

Observers are asked to monitor SDSS091908 nightly beginning immediately (2007 November 07 UT). Visual observers please observe as normal, and report any "fainter than" estimates using the faintest comparison star magnitude you can reach if unable to detect SDSS091908 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=18.3 in reasonable time, but please use sufficient exposure to detect at least the V=14.536 comparison star (AUID 000-BCY-471; RA 09:19:29.70 Dec +08:55:51.8) with a S/N of 10 and report the observation as a "fainter-than" measure.

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. 

Please submit data to the AAVSO using the name "SDSS091908" (AAVSO Designation 0914+09).

Charts for SDSS091908 are available at this URL:  (note: this redirects to an AAVSO VSP chart)

You may also generate custom charts using the RA and Dec given above.

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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