Alert Notice 825: GP Com being observed with HST

May 22, 2023

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Further to AAVSO Alert Notices 823 and 796, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that observations of the cataclysmic variable GP Com have been scheduled with the Hubble Space Telescope on:

2023 25 May 2023 21:37:48 - 26 May 2023 00:02:44 UT

Dr. Pala writes: "We will need to provide the final photometric observations on May 24th by 13:00 UT. The monitoring is showing that the system is stable at V~16 and any data that you can collected on the night of the 23rd will be very valuable to verify that the system is safe to be observed with HST. Thanks for all your work and good luck with the observations!"

Your V observations of GP Com from tonight through May 26 (a few observations per night) are critical. Please continue nightly V snapshots through 2023 June 7.

GP Com has a range of 15.7 - 16.2 V. The most recent observations of it in the AAVSO International Database show it at magnitude 16.534 V +/-0.0952 on 2023 May 19.88495 UT (P. Jordanov, Dimitrovgrad, Bulgaria) and 16.406 V +/-0.135 on May 20.47620 UT (B. Young, Tulsa, OK).

As usual,  it will be crucial to obtain a positive [V] detection of the target the day before the HST observations, in order for the HST team to approve their execution. Please see Alert Notice 796 for additional details and instructions.

Coordinates (J2000):  R.A.  13 05 42.40   Dec.  +18 01 03.8   (from VSX entry for GP Com)

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

Please report observations to the AAVSO International Database using the name GP COM. 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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