Alert Notice 772: V493 Gem to be observed by HST

March 18, 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 V493 Gem (aka ASASSN-14mv), will be observed by the Hubble Space Telescope on 2022 March 25  09:48:13 - 23:55:31 UT.

(HST observations of GP Com, scheduled for January, were postponed by the HST team. Watch the forum threads above for new schedule information when it becomes available.)

Coverage of V493 Gem is requested to begin now and continue through April 15, 2022. Please observe V493 Gem 2-3 times per night though March 26, then nightly through April 15. 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.

A minimum SNR~20 is requested. If the target is too faint to obtain the minimum SNR in V, switch to CV. If the 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 V493 Gem (2000.0): R.A. 07 13 27.28   Dec. +20 55 53.3   (from VSX page for V493 Gem)
Range: 11.7 - 18.2 V
Variability Type: UG/IBWD

Charts with comparison stars for V493 Gem may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations using the name V493 GEM 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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