Alert Notice 698: V386 Ser to be observed with HST

Note: Please see AAVSO Alert Notice 699 for updated HST schedule and observing instructions. - Elizabeth O. Waagen, February 14 2020.

February 7, 2020

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports: https://www.aavso.org/v386-ser-campaign-2020
- Cataclysmic Variables: https://www.aavso.org/v386-ser-campaign-2020-01

Dr. Paula Szkody (University of Washington) has requested AAVSO assistance in monitoring the cataclysmic variable V386 Ser in support of observations scheduled with the Hubble Space Telecope for the week of 2020 February 17-28 UT to obtain a temperature and look for pulsation modes.

Nightly snapshots are requested beginning now and continuing through February 29. Intensive monitoring is requested February 14-29; this period of intensive monitoring will 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 2020 Feb 6.2159 UT it was V=18.409 +-0.161 (S. Dufoer, Brussels, 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.

V386 Ser has been the subject of previous AAVSO observing campaigns, with the most recent campaign having been covered in AAVSO Alert Notices 667, 669, and 675.