HST ULYSSES Southern T Tauri campaign

Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 04/15/2021 - 22:27

REVISED TARGET INFO (as of April 23) IS IN POST BELOW THAT ANNOUNCES ALERT NOTICE 741

UPDATED April 18

Schedules updated April 29

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
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

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 - 2 Sep               ---

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 it's 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 to reflect that.

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.

 

 

Affiliation
American Association of Variable Star Observers (AAVSO)
new sequences

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.

Affiliation
American Association of Variable Star Observers (AAVSO)
Southern T Tau Stars campaign - Alert Notice 741

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: The dates for HM Lup and GQ Lup have been switched - the revised dates are below.

Primary Name Alternate Name RA   (2000) DEC (2000) Range (VSX)  Mean V (not midpoint)  HST (2021 UT) TESS (2021 UT)
CHX 18N 2MASS J11114632-7620092 [Cha] 11 11 46.34 76 20 08.9 11.76 - 12.82 V 11.9 Apr 29 14:30-23:37 Apr 28-May 24
HM Lup Sz 72 15 47 50.63 -35 28 35.4 14.45 - 14.95 V 14.8 May 4 11:30-23:00 Apr 28-May 25
GQ Lup Sz 75 15 49 12.11 -35 39 05.1 11.3 - 14.3 V 11.4 May 3 13:00-01:30 Apr 28-May 25
GW Lup Sz 71 15 46 44.73 -34 30 35.7 13.54 - 14.39 V 13.5 May 5 11:00-23:30 Apr 28-May 25
NSV 20416 Sz 77    [Lup] 15 51 46.96 -35 56 44.1 12.2 - 13.7 V 13.3 May 7 10:30-22:30 Apr 28-May 25
Sz 76 2MASS J15493074-3549514 [Lup] 15 49 30.74 -35 49 51.4 15.1 (0.1) V 15.2 May 10 09:00-20:00 Apr 28-May 25
NSV 20359 Sz 66   [Lup] 15 39 28.28 -34 46 18.1 15.3: - 15.7 V 15.0 May 24 03:30-16:00 Apr 28-May 25
NSV 18716 Sz 45   [Cha] 11 17 36.98 -77 04 38.1 11.8: - 14.1V 13.5 May 25 03:00-14:00 Apr 28-Jun 24
XX Cha   11 11 39.67 -76 20 15.0 13.1 - 15.3 V 15.3 May 29/30 00:00-11:30 Apr 28-Jun 24
GX Cha Hn 5 11 06 41.79 -76 35 49.1 15.8:  - 17.2: V 15.6 May 31 00:00-09:30 May 26-Jun 24
IN Cha   11 12 09.83 -76 34 36.5 15.8 - 16.6 V 16.5 Jun 5/6 21:00-07:00  May 26-Jun 24
T Cha   11 57 13.52 -79 21 31.5 10.09 - 14.5 V 11              ----- Apr 28-Jun 24

Table 2: Southern Targets - HST times to be scheduled (these targets will be moved to Table 1 as they are scheduled)

Primary Name Alternate Name RA   (2000) DEC (2000) Range (VSX) Mean V (not midpoint)  HST (2021 UT) TESS (2021 UT)
SZ Cha   10 58 16.75 -77 17 17.2 11.7 - 13.8 V 12.7 May-Jun Apr 28-Jun 24
TW Cha   10 59 01.06 -77 22 40.9 12.3 - 14.0 V 13.4 late Apr-Jun Apr 28-Jun 24
SSTc2d J160000.6-422158 2MASS J16000060-4221567  [Nor] 16 00 00.60 -42 21 56.8 16.4 - 16.7 V 15.9 Jun 19-23 May 26-Jun 24
NSV 20468 Sz 130   [Lup] 16 00 31.04 -41 43 37.0 13.9 - 15.1 V 14.7 Jun 19-23 May 26-Jun 24
NSV 20520 Sz 111   [Sco] 16 08 54.68 -39 37 43.1 14.1 - 14.6 V 14.0 Jun 18-23 May 26-Jun 24
RU Lup   15 56 42.31 -37 49 15.5 9.8 - 12.9 V 10 10 Aug - 2 Sep         -----

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ