Alert Notice 799: ZTF18acxhphf being observed with HST this week

November 15, 2022

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Further to AAVSO Alert Notice 796, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that observations of the cataclysmic variable ZTF18acxhphf (Aqr) have been scheduled with the Hubble Space Telescope for:

2022 November 17 17:32:14 UT -  November 18 00:50:55 UT

Dr. Pala writes: "Thanks for the data you have been obtained so far, it looks like the target is in quiescence and hopefully will remain like that in the next few days.

"Any data you can collect tonight and tomorrow night is going to be very helpful to assess the safety of the target for the HST detector."

Observers are reminded that a positive V observation no more than 24 hours before the HST observation start-time is required for the HST team to make a decision about allowing the observations to take place. Thus, your observations tonight and tomorrow are critical. This target is very faint at minimum - the most recent observation of ZTF18acxhphf in the AAVSO International Database showed it at magnitude 19.118 V +/-0.179 on 2022 November 14.01017 UT (J. DeYoung, Palmyra, VA).

Please see Alert Notice 796 for additional details and instructions.

Dr. Pala also informs us that HST observations of V479 And, another target in this campaign, have been postponed to December 2022. It will be observed then along with CH UMa (also a campaign target).

Coordinates (J2000):  R.A. 22 52 37.05   Dec. -05 19 17.0  (from VSX entry for ZTF18acxhphf)

Charts with comparison stars for ZTF18acxhphf may be created using the AAVSO Variable Star Plotter (VSP).

Please report observations to the AAVSO International Database using the name ZTF18acxhphf (there are no spaces in the name). Reduce and submit observations as soon as possible after making them.

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


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