Alert Notice 774: TW Hya being observed by HST now - observations needed

March 31, 2022

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Further to AAVSO Alert Notice 770, Dr. Frederick Walter (Stonybrook University) informs us that the final schedule for HST observations of the YSO TW Hya has been announced and observations are underway:

31 Mar 2022 14:20:44 - 15:14:10 UT
01 Apr 2022 14:09:34 - 15:03:00
02 Apr 2022 10:47:52 - 11:59:04
02 Apr 2022 21:54:40 - 22:48:06
03 Apr 2022 15:25:12 - 16:18:38
04 Apr 2022 13:36:17 - 14:29:43
05 Apr 2022 10:14:37 - 11:08:03
06 Apr 2022 17:59:45 - 18:53:11
07 Apr 2022 11:27:35 - 12:21:01
08 Apr 2022 12:51:43 - 13:45:09
09 Apr 2022 07:54:49 - 08:48:15

Dr. Walter notes that "None of these times are good for observers in South America. But please get what you can - at least one set of BVRI observations per night, and we'll piece together what the star is doing. There is no need to observe after the night of April 10." As he commented in Alert Notice 770, "It is important to get single BVRI sequences each night, but longer sets of data would be useful if they can be obtained simultaneously with the HST observations." it is extremely important to have a positive V observation 24 hours before the scheduled HST time. Visual observations are welcome to supplement the light curve.

Coordinates (2000.0): R.A. 11 01 51.91  Dec. -34 42 17.0 (from VSX page for TW Hya)
Range: 10.6-11.3 V
Mean magnitude: V~11

Finder charts with comparison stars for TW Hya may be created using the AAVSO Variable Star Plotter (VSP).

Please submit your observations to the AAVSO International Database using the name TW HYA.

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



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