Note: HST observations have been scheduled for 2024 MAY 18 UT - see Alert Notice 862 for exact times. - Elizabeth O. Waagen, May 14, 2024
May 3, 2024
AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observing Reports: https://www.aavso.org/hst-campaign-dwarf-novae-2023-2024
- Cataclysmic Variables: https://www.aavso.org/hst-campaign-dwarf-novae-2023-2024-01
Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomers and by HQ. Join in the discussion or ask questions there!
Further to AAVSO Alert Notice 838, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that observations of the cataclysmic variable ASASSN-19ct (Cen) have been scheduled with the Hubble Space Telescope for:
2024 May 17 UT
When the exact time is announced, it will be reported in the above forum threads.
Beginning immediately, please observe ASASSN-19ct in V nightly from now through May 10, then one to a few times per night through May 17, then nightly through May 28. 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; the nights of May 14-15, 15-16, and 16-17 will be critical.
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-19ct has a range of 13.4 - 17.8 V and variability type UGSU/IBWD. The most recent observations of it in the AAVSO International Database show it at magnitude 17.451 V +/-0.018 on 2024 May 03.13168 UT (T. Rutherford, Blountville, TN) and visual magnitude <16.2 on May 02.60070 UT (R. Stubbings, Tetoora Road, VIC, Australia).
Coordinates: R.A. 11 33 15.36 Dec. -37 10 20.0 (from VSX entry for ASASSN-19ct)
Charts with comparison stars for ASASSN-19ct may be created using the AAVSO Variable Star Plotter (VSP).
Please report all photometry observations to the AAVSO International Database using the name ASASSN-19ct. 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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