Note: Observations of V1204 with HST have been scheduled; see Alert Notice 766 for details. - Elizabeth O. Waagen, January 14, 2022
Observations of GM Aur are complete. The HST observations of V1204 Tau did NOT take place and will be rescheduled for sometime over the next three months. Please continue to monitor V1204 Tau. - Elizabeth O. Waagen, January 3, 2022
December 2, 2021
AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports: https://www.aavso.org/odysseus-vi-2021-cleanup-targets-01
- Young Stellar Objects: https://www.aavso.org/odysseus-vi-2021-cleanup-targets
Note that these forum threads are NOT the same as for other Alert Notices related to the ODYSSEUS program.
Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomer and by HQ. Join in the discussion or ask questions there!
Further to AAVSO Alert Notice 756, Dr. Frederick Walter (Stony Brook University) informs us that HST observations of two targets (GM Aur, V1204 Tau) in the ULLYSES/ODYSSEUS campaign have been scheduled. AAVSO observers' assistance is requested in monitoring these pre-main sequence targets 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.
GM Aur was scheduled earlier this year for HST observations which were postponed when HST went into safe mode. V1204 Tau has not been on the target list until now.
Dr. Walter provides the following information:
I. GM Aur
04 55 10.97 +30 21 59.7 (J2000) mean V ~ 12.2 range = 11.8-12.6 V (revised per VSX updated parameter)
The HST went into safe-mode on 25 October 2021, after 7 of the planned observations were completed. The AAVSO observations show that the last observation coincided with a small optical brightening. The final 5 observations in this year's monitoring program are scheduled for the week of Dec 6-12.
GM Aur HST schedule (2021)
Dec 06 07 - 09 UT
Dec 07 13 - 15 UT
Dec 08 03 - 05 UT
Dec 10 16 - 17 UT
Dec 12 04 - 06 UT
Please obtain digital BVRI observations nightly now through Dec 13. Multiple observations per night will help us reconstruct the light curve. 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. The Dec 6, 8, and 12 observations occur at night in the western hemisphere; time series (especially in B) simultaneously with the HST observations would be particularly useful.
II. V1204 Tau (HD 285957; RXJ0438.5+1546)
04 38 39.07 +15 46 13.6 (J2000) mean V ~10.8; range = 10.64-10.93 V
This is a newly added target.
HST schedule (2021)
Dec 08 08:31 - Dec 09 0:32 UT
Please obtain digital BVRI observations nightly now through Dec 10. 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 is possible from the western hemisphere late in the night of Dec 7-8 (civil) and early in the evening of Dec 8-9.
For both targets, visual observations are welcome in order to supplement the light curve.
Charts with comparison stars for GM Aur and V1204 Tau may be created using the AAVSO Variable Star Plotter (VSP). The sequence for V1204 Tau is being added to the AAVSO's comparison star database, so if it isn't available in VSP when you first check for it, please save your images and check again later for the sequence.
Please submit observations to the AAVSO International Database, using the name GM AUR or V1204 TAU, in a timely manner, and as soon as possible if any substantial brightening is seen.
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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