Alert Notice 823: SDSS J161909.10+135145.5 and GP Com to be observed by HST

May 2, 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 cataclysmic variables SDSS J161909.10+135145.5 (Her) and GP Com have been scheduled with the Hubble Space Telescope in May.

SDSS J161909.10+135145.5 will be observed on 2023 May 05 02:26 - 08:08 UT

Dr. Pala writes: "Any data you can collect between today and tomorrow [on SDSS J161909.10+135145.5] will be very useful to provide the HST team with the information necessary for the approval. At the moment, the target is coming out of an outburst and is V~16.6 and it should be safe for the HST detectors."

Your V observations of SDSS J161909.10+135145.5 from tonight through May 5 (a few observations per night) are critical. Please continue nightly V snapshots through 2023 May 12.

SDSS J161909.10+135145.5 has a range of 15.2 - 17.9 g. The most recent observations of it in the AAVSO International Database show it at magnitude 16.580 CV +/-0.014 on 2023 Apr. 28.19888 UT (F. Soldan, Seville, Spain) and 16.5424 V +/-0.0180 on Apr. 25.03589 UT (A. Popowicz, Pyskowice, Poland).

GP Com is scheduled to be observed on 2023 May 25; the exact time will be announced in the forum threads above when it is available. Dr. Pala writes: "Thanks for your continuous monitoring of this target, any data you can collect in the next ~20 days will also be very helpful."

Nightly V snapshots are requested beginning now, a few observations per night from May 20 through May 25 (critical interval), and then nightly V snapshots through 2023 June 2.

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 16.074 V +/-0.039 on Apr. 30.13948 UT (F. Soldan, Seville, Spain).

As usual, for both targets 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): 
SDSS J161909.10+135145.5 (Her):   R.A.  16 19 09.10   Dec.  +13 51 45.6   (from VSX entry for SDSS J161909.10+135145.5)
GP Com R.A.  13 05 42.40   Dec.  +18 01 03.8   (from VSX entry for GP Com)

Charts with comparison stars for SDSS J161909.10+135145.5 (be sure to use the full name and include the space after SDSS) and GP Com may be created using the AAVSO Variable Star Plotter (VSP).

Please report observations to the AAVSO International Database using the name SDSS J161909.10+135145.5 and GP COM, respectively. 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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