GM Aur and V1204 Tau - Alert Notice 760

Note: This post from Dr. Walter was made to the YSO forum thread for this campaign in November 2021. It is posted here now (January 3, 2022) because one of the targets it mentions is scheduled to be observed with HST on January 8-9.

There are 3 ULLYSES/ODYSSEUS pre-main sequence targets in December. Two are completions of previously failed observations; one target is new.

Please see previous entries in this Forum for details of the ULLYSES/ODYSSEUS program. Thank you for your contributions to this program over the past year.

I. V505 Ori - POSTPONED UNTIL FURTHER NOTICE AS OF Dec 1, 2021 - RESCHEDULED FOR 2022 JANUARY 08/09 UT - SEE ALERT NOTICE 763
05 38 27.26 -02 45 09.7 (J2000)  mean V = 14.2; range = 14.1-17.2
The Fall 2020 target acquisition failed because the star faded by about 2 mag in B (we know this because of your observations!). The observation will be repeated on UT Dec 02 11-16h (daytime for most of us).
Please obtain digital BVRI observations nightly now through Dec 03 (4 nights). 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.

II. GM Aur - ON SCHEDULE
04 55 10.98  +30 21 59.4 (J2000)  mean V ~ 12.2  range=13.1-13.9p
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 week of Dec 6-12.

HST scheduled UT times
Dec 6   7 -  9 UT
Dec 7  13 - 15 UT
Dec 8   3 -  5 UT
Dec 10 16 - 17 UT
Dec 12  4 -  6 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.

III. V1204 Tau (HD 285957; RXJ0438.5+1546) -- RESCHEDULED FOR 2022 JANUARY 18 UT - SEE ALERT NOTICE 766
04 38 39.072 +15 46 13.57 (J2000)  mean V ~10.8; range=10.64-10.93

This is a newly added target. The HST observations are scheduled for 0831 Dec 08 - 0132 Dec 09 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.

AAVSO Alert Notice 763 announces HST observations of the YSO V505 Ori taking place on 2022 January 08/09 UT. Please see the notice for details and observing instructions.

There are threads for this campaign under the following forums:

- 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

Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ

Alert Notice 766 announces the re-scheduled date of the HST observations of V1204 Tau. Please see the notice for details and observing instructions.

There are threads for this campaign under the following forums:

- 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

Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ