Alert Notice 806: Schedule for BP Tau observations with HST

December 29, 2022

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Further to AAVSO Alert Notice 802, Dr. Frederick Walter (Stony Brook University) informs us that HST observations of the classical T Tau star BP Tau  have been scheduled for:

31 Dec 2022 15:34:08 - 16:24:58 UT
02 Jan 2023 13:34:05 - 14:24:55
04 Jan 2023 14:44:26 - 15:35:16
06 Jan 2023 11:09:12 - 12:00:02

Photometry leading up to, or during the HST observations, will be particularly useful.

Dr. Walter provides the following information and instructions:

"ODYSSEUS is an international collaborative campaign to understand the processes involved in the formation of low mass stars, their circumstellar disks, and their planets, via the time-variability of these systems. Please read other Alert Notices (starting from AAVSO Alert Notice 725) and forum notes on this program for more details.

Observations of the final HST/ULLYSES/ODYSSEUS target, BP Tau, are underway. "This is a monitoring target, so the HST will obtain UV spectra over the coming week. BP Tau will not be observed by TESS during this period.

Target Details:
Target        RA  (J2000)  Dec               <V>      Range           HST  observation dates
BP Tau     04 19 15.83 +29 06 26.9    12.1     11.5-12.7 V    31 December 2022 - 06 January 2023 (see exact times above)

"I ask that those of you who can to obtain CCD filter photometry (BVRI preferred, and U if you can) at least nightly for BP Tau through January 7 to establish the trends in the color variability. Time-series during the actual HST intervals would be very valuable. Typical variability timescales are a few hours.  Note that since there will be no TESS coverage of BP Tau during this period, your photometry will be even more important.

"Please try to obtain 1% S/N (0.01 mag), so that colors are accurate to about 2% (0.02 mag).

"Thanks again for contributing to a very successful and productive program."

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

Please submit observations to the AAVSO International Database using the name BP TAU.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Dr. Walter.


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