Alert Notice 766: V1204 Tau observations needed now for HST coverage

January 14, 2022

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
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Note that these forum threads may not be the same as for other Alert Notices related to the ODYSSEUS program.

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Further to AAVSO Alert Notice 760, Dr. Frederick Walter (Stony Brook University) informs us that HST observations of V1204 Tau have been scheduled for 2022 January 18 04:30-11:40 UT. V1204 Tau, a target in the ULLYSES/ODYSSEUS campaign, was originally scheduled to be observed in December.

AAVSO observers' assistance is requested in monitoring this pre-main sequence target before, during, and after the HST observations. As always with HST observations, a positive V observation is crucial 24 hours before the scheduled start time to allow the HST team to make a go/nogo decision.

Dr. Walter provides the following information:

"Thanks to all of you who have been observing our T Tauri star targets....The [HST] observations of V1204 Tau last month apparently failed, because they have been rescheduled for January 18, 0430-1140 UT.

"Please add V1204 Tau to your target list from now through January 19. Please obtain digital BVRI observations nightly. Multiple observations per night will help us reconstruct the light curve, and establish the photometric phase (the rotational period is 3.08 days). There will not be any TESS observations. B and V are more valuable than R and I because stellar variability is more prominent at short wavelengths. Simultaneity with the start of the HST observations is possible from the western hemisphere late on the night of Jan 17-18 (civil)."

Visual observations are welcome in order to supplement the light curve.

Coordinates (2000): 04 38 39.07 +15 46 13.6 (J2000)   (from VSX page for V1204 Tau)
mean V ~10.8; range = 10.64-10.93 V

Charts with comparison stars for V1204 Tau may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations to the AAVSO International Database, using the name V1204 TAU, in a timely manner, and as soon as possible if any substantial brightening is seen.

AAVSO Alert Notices 725, 728, 731, 733, 737, 741, 748, 751, and 756 also cover targets in the ULLYSES/ODYSSEUS campaign; some also give detailed information about the campaign itself.

Observers are encouraged to subscribe to the forum threads above and use them to discuss any interesting observations and post questions or comments for Dr. Walter.

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


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