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Alert Notice 669: V386 Ser HST observations rescheduled

June 21, 2019: Further to AAVSO Alert Notice 667, Dr. Paula Szkody (University of Washington) informs us that the HST observations of the cataclysmic variable V386 Ser originally scheduled for last month have been rescheduled for 2019 August 1 - 3 (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.

Please continue obtaining nightly snapshots through August 10. They are particularly important from July 15 on, when frequent reports will have to be relayed to the HST scheduling team. Intensive monitoring is requested July 27 through August 4; 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 below) 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 June 14.0831 UT it was V=18.934 +/-0.495 (E. Schwendeman, Fincastle, VA). 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 a comparison star sequence 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.

AAVSO Forums: This campaign continues to be the topic of the AAVSO Campaigns and Observation Reports forum thread https://www.aavso.org/v386-ser-campaign-2019 and the Cataclysmic Variables forum thread https://www.aavso.org/v386-ser-campaign-2019-01

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

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