January 31, 2022
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Further to AAVSO Alert Notice 758, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that the next target in their program, the cataclysmic variable V1239 Her, will be observed by the Hubble Space Telescope on February 15, 2022. (HST observations of GP Com, scheduled for January, have been postponed by the HST team, possibly until March.)
Coverage of V1239 Her is requested to begin now and continue through March 7, 2022. Please observe V1239 Her nightly though February 7, then 3-4 times per night through February 16, then nightly through March 7. As with all targets for HST, it will be crucial to have a positive V measurement 24 hours before the scheduled HST time so the HST team can make a go-nogo decision.
Please note that V1239 Her is an eclipsing system with an orbital period of 144 minutes, while the eclipse lasts ~10 minutes. The ephemeris may be found on the VSX page for V1239 Her.
A minimum SNR~20 is requested. If the target is too faint to obtain the minimum SNR in V, switch to CV. If a target is observed going into outburst, please submit your observation(s) as soon as possible and begin obtaining multiple observations per night.
Dr. Pala writes: "We know that some observers carry out time-series observations and also spectroscopy, and we welcome any additional contributions. Nonetheless the monitoring to assess quiescence should have the highest priority since, without it, there is the risk to lose the allocated orbits.
"In case of time-series observations, an uninterrupted light curve in a single filter (preferably B or V) would be better than alternating with different filters. CV observations can still be useful but V-filter observations should be the priority (whenever possible).
"DSLR observations, particularly if they are transformed to V, will be useful and are welcome. Visual observations will also be very valuable."
Coordinates for V1239 Her (2000.0): R.A. 17 02 13.25 Dec. +32 29 54.2 (from VSX page for V1239 Her)
Range: 13.7 CR-19.1 V
Variability Type: UGSU+E
Charts with comparison stars for V1239 Her may be created using the AAVSO Variable Star Plotter (VSP).
Please submit observations using the name V1239 HER to the AAVSO International Database.
This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Dr. Pala.
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