Alert Notice 833: LL Lyr to be observed with HST in September/October

September 20, 2023

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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 magnetic cataclysmic variable LL Lyr  are upcoming with the Hubble Space Telescope and reports that although they were originally planned for September, they have not been scheduled yet and may be delayed until October.

Please watch the above forums for the date and time; they will be posted there when Dr. Pala is informed by the HST scheduling team.

Nightly V snapshots are requested from now through two weeks after the HST observations take place. Once the date and time are announced, V observations will be critical in the few days before the HST date; a positive V observation is required 24 hours before the date so the HST team can make a go/nogo decision.

Dr. Pala writes: "Thanks a lot for the data on V584 Lyr! With these observations we could show to the HST team that the target was safe for the detectors and the observations were successfully completed :).  We don't have a date for LL Lyr yet. It is possible that the observations will be delayed to October because of other constraints on the HST schedule. I'll post here when I have more details. Thanks once more to you all for your support!"

LL Lyr has a range of 12.9 - 18.5 V. The most recent observations of it in the AAVSO International Database show it at V magnitude 17.649 +/- 0.131 on 2023 Sep.18.83551 UT (A. Steenkamp, Horsham, W. Sussex, UK)  and <14.9 visual on Sep. 20.12640 UT (T. Benner, Perkasie, PA).

Please see Alert Notice 796 for additional details and instructions.

Coordinates (J2000):  R.A. 18 35 12.82    Dec. +38 20 04.3    (from VSX entry for LL Lyr)

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

Please report observations to the AAVSO International Database using the name LL LYR. 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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