Note: TW Vul was successfully observed by HST. Please continue the nightly snapshots through July 12, as requested below. Many thanks! - Elizabeth O. Waagen, July 2, 2024
June 25, 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
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Further to AAVSO Alert Notice 838, Dr. Anna Francesca Pala (European Space Agency, ESAC, Spain) informs us that observations of the cataclysmic variable TW Vul have been scheduled with the Hubble Space Telescope for:
2024 June 28 03:43:10 - 06:17:23 UT
Positive observations in V over the next few nights - especially on the 26th and 27th - are crucial. Please observe TW Vul one to a few times per night through June 28, then nightly through July 12. 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."
TW Vul has a range of 12.8 - 18.4 V and variability type UG. The most recent observation of it in the AAVSO International Database shows it at magnitude 18.346 CV +/-0.205 on 2024 June 16.94456 UT (S. Dufoer, Brussels, Belgium).
Coordinates: R.A. 20 39 34.48 Dec. +27 15 55.8 (from VSX entry for TW Vul)
Charts with comparison stars for TW Vul may be created using the AAVSO Variable Star Plotter (VSP).
Please report all photometry observations to the AAVSO International Database using the name TW VUL. 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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SUBMIT OBSERVATIONS TO THE AAVSO
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