Alert Notice 863: ASASSN-20pv being observed with HST May 30-31

Note: The HST team informed Dr. Pala today that due to technical issues with HST, observations of ASASSN-20pv have been cancelled. Dr. Pala is working on the rescheduling of this target. In the meantime, continued nightly snapshots in V would be very valuable.  -  Elizabeth O. Waagen, May 29, 2024

May 29, 2024

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Further to AAVSO Alert Notice 861, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that observations of the cataclysmic variable ASASSN-20pv (Vel) have been scheduled with the Hubble Space Telescope for:

2024 May 30 21:05:55 - May 31 00:18:45 UT 

Positive observations in V tonight (May 29-30) are crucial. Please observe ASASSN-20pv one to a few times per night tonight and tomorrow night (through May 31), then nightly through June 9. As with all targets for HST, it will be crucial to have a positive V measurement 24 hours before the scheduled HST time so the HST team can make a go-nogo decision.

A minimum SNR~20 is requested. If the target is too faint to obtain the minimum SNR in V, switch to CV. If a target is observed going into outburst, please submit your observation(s) as soon as possible and begin obtaining multiple observations per night.

Dr. Pala writes: "We know that some observers carry out time-series observations and also spectroscopy, and we welcome any additional contributions. Nonetheless the monitoring to assess quiescence should have the highest priority since, without it, there is the risk to lose the allocated orbits.

"In case of time-series observations, 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).

"DSLR observations, particularly if they are transformed to V, will be useful and are welcome. Visual observations will also be very valuable."

ASASSN-20pv has a range of 12.3 g - 17.4 V and variability type UGSU/IBWD. The most recent observation of it in the AAVSO International Database shows it at magnitude 17.262 V +/-0.022 on 2024 May 28.36069 UT (G. Myers, Hillsborough, CA).

Coordinates: R.A. 10 40 19.50   Dec. -49 51 29.7   (from VSX entry for ASASSN-20pv)

Charts with comparison stars for ASASSN-20pv may be created using the AAVSO Variable Star Plotter (VSP).

Please report all photometry observations to the AAVSO International Database using the name ASASSN-20pv. 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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