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Alert Notice 675: V386 Ser - second rescheduling of HST observations

Note: Dr. Szkody informs us that the HST observations of V386 Ser have been scheduled for 2019 Aug 15  22:04:49 UT - Aug 16 00:31:52 UT. The critical night is August 14 - please report your observations of V386 Ser as soon as possible after you make them so that HST can be notified in time to make the go-nogo decision. - Elizabeth O. Waagen, August 6, 2019

August 2, 2019

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
  -   Campaigns and Observing Reports: https://www.aavso.org/v386-ser-campaign-2019
  -   Cataclysmic Variables: https://www.aavso.org/v386-ser-campaign-2019-01

Further to AAVSO Alert Notices 669 and 667, Dr. Paula Szkody (University of Washington) informs us that the HST observations of the cataclysmic variable V386 Ser originally scheduled for June and rescheduled to early August have been rescheduled again for 2019 August 15 or 16 (the exact date and time are not yet known).

It is essential to continue obtaining nightly snapshots in order to know the status of this system from now through the HST observation window. Your patience with these reschedulings is very much appreciated, as are your ongoing crucial observations!

Please continue obtaining nightly snapshots through August 23. They are particularly important from August 4 on, when frequent reports will have to be relayed to the HST scheduling team. Intensive monitoring is requested August 12 through August 17; this period of intensive monitoring may be adjusted when the exact time of the HST observations is known. When the exact time is known, it will be posted to the AAVSO forum thread on this campaign (see above) and this Alert Notice will be updated online. During the period of intensive observations, prompt submission of observations will be critical.

AAVSO observations are essential to know the state of the V386 Ser system in order to ensure that the system is NOT in outburst when observed with HST. AAVSO observations made 24 hours before the HST observing time will be used to make a go/no-go decision; AAVSO data will be used in the analysis of the resulting HST data.

V386 Ser (UGWZ+ZZ/GWLIB = WZ Sge type with a non-radially pulsating white dwarf) is faint at quiescence (V~19.2). It had an outburst in January 2019, and on 2019 August 2.0795 UT it was CV = 17.815 +/-0.063 (F.-J. Hambsch, Mol, Belgium). There is a V=17.757 star to the NW of the variable (178 in the AAVSO comparison star sequence; R.A. 16 10 33.15 Dec. -01 02 14.2); knowing whether the variable is fainter than, comparable to, or brighter than it will be very useful.

If visual observers are unable to detect V836 Ser, please report any "fainter-than" estimates using the magnitude of the faintest comparison star magnitude seen. CCD observers are asked to use filters during observations if available; V is preferred. Detection of the variable itself is not required unless you can reach V=18.4 in reasonable time, but please use sufficient exposure to detect at least the 178 comparison star with a S/N of 10 and report the observation as a "fainter-than" observation. V386 Ser may be as bright as V=10.4 in outburst.

Coordinates (J2000): R.A. 16 10 33.63  Dec. -01 02 23.2

Charts with comparison stars for V386 Ser may be created using the AAVSO Variable Star Plotter (VSP).

Please report all observations to the AAVSO International Database using the name V386 SER.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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