REVISED TARGET INFO (as of April 23) IS IN POST BELOW THAT ANNOUNCES ALERT NOTICE 741
UPDATED April 18. June 17, July 17, July 30
JUNE 17 UPDATE: Due to an HST safing event, the observations of Sz 111, Sz 130, and STc2d J160000.6-4221582, scheduled for this weekend, are unlikely to be done. The targets are still in the TESS observing window, so please keep observing. Details on rescheduling will be posted when available.
July 17 UPDATE: HST observations have resumed. Two targets are re-scheduled for next week:
- Sz 130: 22 Jul 2021 13:17:02 - 22 Jul 2021 21:32:41
- STc2dJ 160000.6-422158: 23 Jul 2021 04:28:52 - 23 Jul 2021 16:19:45
Please add these two targets to your observing queue if practical, through July 22 (Sz 130) or July 23 (SSTC2DJ160000.6-422158).
July 30 UPDATE: HST will observe Sz 76 on August 8 from 11:27:38 through 18:56:12 UT. Please add this target to your observing queue if practical. There will be no TESS data, so frequent (at least nightly) BVRI observations will be helpful for setting the context for the HST spectra.
12 nights of monitoring observations of RU Lup are scheduled Aug 10-21. Details will be forthcoming soon.
Part III of the ODYSSEUS pre-main sequence star program starts later this month. 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.
Thanks to all of you who participated in and obtained data for parts I (13 northern T Tauri stars) and II (monitoring of TW Hya) of this program.
The HST will obtain snapshots of a number of pre-main sequence (T Tauri) stars in the south over the coming months. The 17 targets for his campaign are all brighter than V~16. Most of these observations will take place while the targets are in the TESS field, yielding about 27 days of continuous 600-1000nm photometry with a 10 minute cadence.
TESS data, both in terms of length of coverage and data quality, cannot be matched from the ground, but TESS is a single channel photometer operating in the red. We need ground-based optical photometry to place the TESS magnitudes in context, and determine what the stars may have been doing when HST was observing them.
- Pre-main sequence stars may experience enhanced accretion events or long-lived flares, either of which cause the star to become bluer, and
- they may experience variable circumstellar extinction, which may cause the star will become redder, or
- if the variable extinction is caused by optically-thick (opaque) irregularities in the circumstellar disk, their colors may not change as they fade.
Clearly, changes in extinction in particular are important for interpreting the UV spectra, which are very sensitive to the absorption.
The targets scheduled for late April through early June are:
Target RA (2000) DEC <V> HST plan TESS
CHX18N 11 11 46.32 -76 20 09.2 11.9 April 29 14:30-23:37 4/28 - 6/24
GQ Lup (Sz75) 15 49 12.10 -35 39 05.1 11.4 May 3 13:00-01:30 4/28 - 5/25
HM Lup (Sz72) 15 47 50.63 -35 28 35.4 14.8 May 4 11:30-23:00 4/28 - 5/25
GW Lup (Sz71) 15 46 44.73 -34 30 35.5 13.5 May 5 11:00-23:30 4/28 - 5/25
Sz77 15 51 46.95 -35 56 44.1 13.3 May 7 10:30-22:30 4/28 - 5/25
Sz76 15 49 30.74 -35 49 51.4 15.2 May 10 0900-20:00 4/28 - 5/25
Sz76 revisit 15 49 30.74 -35 49 51.4 15.2 June 29 see note for June 17
Sz76 revisit 2 15 49 30.74 -35 49 51.4 15.2 August 8 11:27 - 18:56
Sz66 15 39 28.28 -34 46 18.0 15.0 May 24 03:30-16:00 4/28 - 5/25 see note
Sz45 11 17 37.00 -77 04 38.1 13.5 May 25 03:00-14:00 4/28 - 6/24
XX Cha 11 11 39.65 -76 20 15.2 15.3 May 29/30 0:00-11:30 4/28 - 6/24
GX Cha (HN 5) 11 06 41.79 -76 35 48.9 15.6 May 31 0:00-09:30 5/26 - 6/24
IN Cha 11 12 09.84 -76 34 36.6 16.5 June 5/6 21:00-07:00 5/26 - 6/24
Sz 130 16 00 31.25 -41 43 37.2 14.7 July 22 13:17 - 21:32 5/26 - 6/24 See note for July 17
SZ 111 16 08 54.69 -39 37 43.1 14.0 June 20 18:12 - 22:19 5/26 - 6/24
STc2d J160000.6-4221582 16 00 00.60 -42 21 56.8 July 23 04:29 - 16:19 5/26 - 6/24 See note for July 17
T Cha 11 57 13.44 -79 21 31.7 11 --- 4/28 - 6/24
RU Lup 15 56 42.31 -37 49 15.5 10 10 Aug - 21 Aug ---
Target Notes:
- The TESS column indicates the dates that the target is in the TESS field. CHX18N and T Cha are near the ecliptic pole, and will be viewed for 54 days.
- Note that the HST times are preliminary and may yet change, but it is likely they will fall within the posted window.. The final schedule will be posted here when available.
- T Cha is not an HST target; please obtain occasional observations while the target is in the TESS window to let us correlate colors with TESS magnitudes.
- RU Lup will be monitored by the HST for 12 days during its plan window. It will not be observed with TESS.
- Information on the other targets in this campaign will be posted as it becomes available.
- ADDED 4/26: Please note that Sz66 is located 6" from a brighter star (Sz 65; delta-mag ~ 3 at V). Please do not waste time on this star if the seeing is bad, or unless you have a good plate scale. Also, please check the mean V magnitudes - some of these targets are on the faint side.
- Added 4/28: The dates for GQ Lup and HM Lup have been swapped. The Table has been updated.
- Added 5/21: Sz 111 and Sz 130 are now scheduled for June 20. The table has been updated.
- Added 6/15: STc2d J160000.6-4221582 is now scheduled for June 21. The table has been updated.
The first HST observation of Sz 76 failed, and has been rescheduled for June 29. There will be no TESS coverage, so ground-based photometry is crucial.
- Added 7/17: HST observations of Sz 130 and STc2d J160000.6-4221582 have been re-scheduled for July 22 and July 23, respectively. There will be no TESS coverage, so ground-based photometry is crucial.
Timing Requirements: CCD filter photometry on the 3 nights surrounding the HST observation. Observe during the time of the HST observation, if possible.
If not possible (2/3 of the HST observations will take place while the target is below the horizon or in daylight from any particular observatory), please get CCD filter photometry before and after the HST observations. There is no need to obtain long time series: TESS will provide that.
Filter Requirements: It is important to use standard broadband filters. Concentrate on B and V, which TESS does not observe, and on Rc and Ic, which will enable cross-calibration with TESS. T Tauri stars tend to be more variable at shorter wavelengths.
TESS color calibration: Two or more sets of BVRcIc observations during the 27 day TESS window will help us “calibrate” the TESS photometry, and correlate color changes with brightness changes.
Please upload any data you get to the AAVSO database. Thanks in advance for your contributions to this campaign.
Okay, We should now have sequences for all the stars on the HST/TESS list that didn't have them before, with one exception: Sz 66 = nsv 20359 will probably not be observable as not only is it about 5 arcsec from another variable, but the pair themselves are unhealthily close to a 9m star.
AAVSO Alert Notice 741 announces a campaign on several Southern T Tauri stars in support of HST and TESS observations. 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/hst-ulysses-southern-t-tauri-campaign-01
- Young Stellar Objects: https//www.aavso.org/hst-ulysses-southern-t-tauri-campaign
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!
The tables below contain the targets. They will be updated as HST times are added or revised, so please check them frequently! Also, be sure to read the Alert Notice to see Notes pertaining to these targets.
Table 1: Scheduled Southern Targets
****Note 5/25/21: The targets NSV 20468 (Sz 130) and NSV 20520 (Sz 111) have been scheduled for HST. They have been moved from Table 2 to Table 1.
The dates for HM Lup and GQ Lup have been switched - the revised dates are below.
Table 2: Southern Targets - HST times to be scheduled (these targets will be moved to Table 1 as they are scheduled)
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
HST is observing two targets from this campaign TONIGHT or TOMORROW. AAVSO Alert Notice 748 gives information for the two targets (NSV 20468 (= Sz 130) [Lup] and SSTc2d J160000.6-422158 [Nor]). Please see the notice for observing instructions.
Many thanks, and good observing,
Elizabeth O. Waagen, AAVSO HQ