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cataclysmic variable

Alert Notice 597: GW Lib time set for third HST observation

September 6, 2017: Further to AAVSO Alert Notices 591, 595, and 596, Dr. Boris Gaensicke (Warwick University) informs us that the date and time for the third and final of three HST observations in his campaign on the pulsating white dwarf-containing cataclysmic variable GW Lib has been scheduled for

2017 Sep 13 23:52:02 to Sep 14 04:30:12 UT.

Alert Notice 596: GW Lib time set for second HST observation

August 31, 2017: Further to AAVSO Alert Notices 591 and 595, Dr. Boris Gaensicke (Warwick University) informs us that the date and time for the second of three HST observations in his campaign on the pulsating white dwarf-containing cataclysmic variable GW Lib has been scheduled for

2017 Sep 6 22:36:04 to Sep 7 02:49:26 UT.

Variable Star of the Season Archive

The following articles contain useful and interesting information on individual variable stars. Many of the most popular stars in the AAVSO observing program are featured.  From December 1998 until December 2002, the collection of articles comprised the "Variable Star of the Month" series. Since that time, they have all been published as part of the "Variable Star of the Season" (VSOTS) collection. Each article is available in either .html or .pdf format.

Variable Stars and the Stories they Tell

What are variable stars and why are astronomers interested in them?

Alert Notice 595: GW Lib time scheduled for first HST observation

August 24, 2017: Further to AAVSO Alert Notice 591, Dr. Boris Gaensicke (Warwick University) informs us that the first of three HST observations in his campaign on the pulsating white dwarf-containing cataclysmic variable GW Lib has been scheduled for

2017 Aug 31 20:52:02 to 2017 Sep 1 02:12:21 UTC.

Alert Notice 591: GW Lib observations requested in support of K2 and HST observations

August 7, 2017: Dr. Boris Gaensicke (Warwick University) has requested our help in monitoring the pulsating white dwarf-containing cataclysmic variable GW Lib in preparation for and support of K2 (Kepler's Second Light) and Hubble Space Telescope (HST) observations scheduled for August to November 2017 and August and September 2017, respectively.

K2 will be observing GW Lib non-stop 2017 Aug 23 20:00:00 to 2017 Nov 19 23:00:00 UTC.

Alert Notice 588: Long-term CCD monitoring of ER UMa-type variable DDE 48 in Vulpecula

July 21, 2017: The following request for AAVSO assistance has been received from Denis Denisenko (Sternberg Astronomical Institute, Moscow State University) to help characterize "...the cataclysmic variable DDE 48 in Vulpecula. This CV belongs to the rare ER UMa subtype of dwarf novae, with only 6 other stars in VSX being classified as UGER. According to 2016-2017 observations by Nikolay Mishevskiy (MNIC) and Denis Denisenko (DDE), this variable is very active, with superoutbursts to magnitude V=15.4 occurring approximately once a month.

Special Notice #71: Next HST cataclysmic variable scheduled

October 11, 2007: The next HST object from Paula Szkody's program is scheduled to be observed during the week of October 29 through November 3. This is SDSS J074531.92+453829.5, another cataclysmic variable that is about V=19.1 at quiescence, and unknown brightness in outburst since it has never been observed to outburst. The coordinates are:

07:45:31.92 +45:38:29.5 J2000

and the AAVSO Harvard Designation and name is

0738+45 SDSS074545

Special Notice #63: Outburst in HS 2331+3905 [V455 And]

September 4, 2007: The WZ Sge-candidate object HS 2331+3905 [V455 And] has been reported in outburst on VSNET by two observers. This object was last reported as fainter than 14.6 on JD 2454347.3931 (Sept 3, 2007, 21:26 UT), and has now been detected at 14.59 and 14.4 by observers in Japan. HS 2331+3905 has never been observed in outburst before, and observations are strongly encouraged.

Special Notice #67: Special Notice #66 on V455 AND Corrected

September 12, 2007: Due to a typographical error, the lead sentence of AAVSO Special Notice #66 was garbled. My sincere apologies! Here is the correct version:

According to IAU Circular No. 8868 (Daniel E. W. Green, editor), N. N. Samus, Institute of Astronomy, Moscow, reports that the dwarf nova cataclysmic variable 2328+38 HS 2331+3905 has been assigned the official name V455 And. The AAVSO validation file has been changed to reflect this new name. Please use V455 AND when reporting observations.

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