Alert Notice 769: V704 And in low state - to be observed by HST

February 11, 2022

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Further to AAVSO Alert Notice 754, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that Target-of-Opportunity observations with the Hubble Space Telescope have been scheduled for the VY Scl novalike cataclysmic variable V704 And, which has gone into its low state.

HST will observe V704 And on February 22, 2022.

Dr. Pala writes to the AAVSO observers: "It would be great if you could give the highest priority to the observations of V704 And and try to obtain at least one positive measurement [ideally in V or CV] per night, till Feb 23rd. These data will be used to confirm that the HST observations will indeed be obtained while the target is still in low state and it is safe to be observed with COS."

A minimum SNR~20 is recommended. If the target is too faint to obtain the minimum SNR in V, switch to CV. As always with HST observations, a positive observation 24 hours before the scheduled observing time is required by the HST scheduling team to make a go/no-go decision. When the exact time of the observations is known, it will be posted in the forum threads above.

If time-series observations are made, 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).

It will also be valuable to know when V704 And returns to its bright state, so ongoing nightly observations a few times per week would be appreciated until the target has returned to its bright state.

Please see Alert Notice 754 for more information about this campaign.

Coordinates (2000.0): R.A. 23 44 57.51  Dec. +43 31 22.3 (from VSX page for V704 And)
Range: 12.6 - 19.5 CV

Charts with comparison stars for V704 And may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations as soon as possible after making them to the AAVSO International Database using the name V704 AND.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Dr. Pala.



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