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AAVSO 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

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:

http://tinyurl.com/26shem  (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.


Information on submitting observations to the AAVSO may be found at:



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