15476( 4) - 14-Dec-2018 15:54:14 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15476 Version: 4 Check-in Time: 14-Dec-2018 15:54:14 STScI Edit Number: 1 Title The Formation History of Milky Way Satellite Canes Venatici I ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Daniel R. Weisz University of California - Berkeley Y CoI: Dr. Nitya Kallivayalil The University of Virginia N CoI: Prof. Michael Boylan-Kolchin University of Texas at Austin N CoI: Ms. Tom Zick University of California - Berkeley N CoI: Mr. Sean Linden The University of Virginia N CoI: Paul Zivick The University of Virginia N ------------------------------------------------------------------------------------ Abstract We propose deep ACS/WFC and WFC3/UVIS F606W and F814W imaging of Milky Way (MW) satellite Canes Venatici I (CVn I) to measure its star formation history (SFH) and establish first epoch imaging for its proper motion (PM) determination. CVn I (Mv = -7.9) is a distant ( ~220 kpc) MW satellite that straddles the boundary between ultra-faint and classical dwarf galaxy. It is among the most diffuse, faint satellites in the local Universe (r_h > 500pc, mu=28.1 mag/arcsec^2), but whether its low density is intrinsic or environmentally driven remains unknown. The SFH and PM motion measurements enable a wide range of immediate and long term science including (1) determining if the timing and intensity of star formation can explain CVn I's low density through dark matter core creation; (2) examining how reionization impacts galaxy formation in this transitional mass regime; (3) checking if the sub-Solar stellar IMF follows the trends established in other ultra-faint galaxies; (4) determining if CVn I's orbital history includes a close pericentric passage (< 20kpc) to the MW's disk, which would have tidally disturbed CVn I; (5) providing one of the most precise measurements of the total mass of the MW's halo. Furthermore, this program will put CVn I on same observational footing as all other MW satellites. Only HST can achieve any of these science goals. However, all archival HST observations of CVn I are inadequate. Maximizing the time baseline for PM measurement is scientifically imperative, but it will be 2 cycles until normal channels for small programs are restored. Waiting will substantially compromise the precision of the PM determination. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will image CVn I using the F606W and F814W filters of ACS/WFC and WFC3/UVIS. Our imaging will reach high S/N at the oldest main sequence turnoff in multiple fields, allowing us to measure the detailed star formation history (SFH) of CVn I across all cosmic time. Our imaging is well-dithered, and thus establishes a first epoch proper motion baseline, and is deep enough to explore the sub-Solar stellar initial mass function. 15476( 4) - 14-Dec-2018 15:54:14 - [ 2] Our observing plan generally follows that specificed in the GO-14734, a Treasury survey of Milky Way satellites, which did not include CVn I. Our program consists of two adjacent ACS pointings located within the half-light radius. Each pointing is allocated 4 orbits, two in F606W and two in F814W, spread out over two visits. Each orbit is executed as a single filter and divided into long exposures (~1100-1300 sec per filter) in order to minimze overheads. For a single orbit in each filter, we add a short intergration (60 sec) to mitigate any potential saturation issues with bright stars. We use POS-TARG commands to implement the 4 point dither pattern specified by the ACS users handbook. This dither pattern satisfies PSF sampling requirements for consistent astrometic fidelity with observations of other MW satellites. WFC3/UVIS observations are taken in parallel mode, and follow a similar observing strategy to ACS. For the 60 sec UVIS exposures, we use FLASH=10. To maximize schedulability of this program, we only constrain the roll angle to avoid bright foreground stars that may negatively affect the parallels. However, we do require that differnet visits for the same pointings have the same ORIENTATION. Given the minimal roll angle constraints and the diffuse nature of CVn I, there is a >50% chance that one of the UVIS fields will sample stars within the galaxy's half-light radius. ------------------------------------------------------------------------------------ 15476( 4) - 14-Dec-2018 15:54:14 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CVN-I-DSPH-1 GALAXY, DWARF RA=13H28M18.2939S, J2000 V = 19 +/- 1 SPHEROIDAL DEC=+33D35'1.34" Reference Frame: Other: NED Comments: Faintest targets have V~28-29. A few foreground stars with V~13 ------------------------------------------------------------------------------------------------------------------------------------ 2 CVN-I-DSPH-2 GALAXY, DWARF RA=13H28M2.0601S, J2000 V = 19 +/- 1 SPHEROIDAL DEC=+33D33'30.88" Reference Frame: Other: NED Comments: Faintest targets have V~28-29. A few foreground stars with V~13 ------------------------------------------------------------------------------------------------------------------------------------ 15476( 4) - 14-Dec-2018 15:54:14 - [ 4] Visit: 01 Visit Requirements: ORIENT 15D TO 215 D; ORIENT 270D TO 320 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1269 S POS TARG 0.0, 0.0; PAR 2 1 (1269 S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS F606W 1 1229 S S see below (1320 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1260 S POS TARG 0.148, 0.086; 1 (1260 S) PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS F606W 1 1229 S S see below (1270 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 60 S (60 POS TARG 0.222, 0.240; 1 S) PAR 6 WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY WFC3/UVI ACCUM UVIS F606W FLASH=10 1 60 S (60 S S) ------------------------------------------------------------------------------------------------------------------------------------ 7 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1240 S POS TARG 0.222, 0.240; 1 (1240 S) PAR 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY WFC3/UVI ACCUM UVIS F606W 1 1230 S S see below (1250 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1280 S POS TARG 0.074, 0.154; 1 (1280 S) PAR 10 WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY WFC3/UVI ACCUM UVIS F606W 1 1300 S S see below (1366 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CVN-I-DSPH-1 1 ACS/WFC ACCUM WFC F606W none none none none 1 N/A 15476( 4) - 14-Dec-2018 15:54:14 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ANY 2 WFC3/UVI ACCUM UVIS F606W none none none none 1 1320.0 S S CVN-I-DSPH-1 3 ACS/WFC ACCUM WFC F606W none none none none 1 N/A ANY 4 WFC3/UVI ACCUM UVIS F606W none none none none 1 1270.0 S S CVN-I-DSPH-1 5 ACS/WFC ACCUM WFC F606W none none none none 2 N/A ANY 6 WFC3/UVI ACCUM UVIS F606W none none none none 2 N/A S CVN-I-DSPH-1 7 ACS/WFC ACCUM WFC F606W none none none none 2 N/A ANY 8 WFC3/UVI ACCUM UVIS F606W none none none none 2 1250.0 S S CVN-I-DSPH-1 9 ACS/WFC ACCUM WFC F606W none none none none 2 N/A ANY 10 WFC3/UVI ACCUM UVIS F606W none none none none 2 1366.0 S S 15476( 4) - 14-Dec-2018 15:54:14 - [ 6] Visit: 02 Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1269 S POS TARG 0.0, 0.0; PAR 2 1 (1269 S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS F814W 1 1229 S S (1229 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1260 S POS TARG 0.148, 0.086; 1 (1260 S) PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS F814W 1 1229 S S (1229 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 60 S (60 POS TARG 0.222, 0.240; 1 S) PAR 6 WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY WFC3/UVI ACCUM UVIS F814W FLASH=10 1 60 S (60 S S) ------------------------------------------------------------------------------------------------------------------------------------ 7 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1240 S POS TARG 0.222, 0.240; 1 (1240 S) PAR 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY WFC3/UVI ACCUM UVIS F814W 1 1230 S S (1230 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1280 S POS TARG 0.074, 0.154; 1 (1280 S) PAR 10 WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY WFC3/UVI ACCUM UVIS F814W 1 1300 S S (1300 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CVN-I-DSPH-1 1 ACS/WFC ACCUM WFC F814W none none none none 1 N/A ANY 2 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S CVN-I-DSPH-1 3 ACS/WFC ACCUM WFC F814W none none none none 1 N/A ANY 4 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S 15476( 4) - 14-Dec-2018 15:54:14 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CVN-I-DSPH-1 5 ACS/WFC ACCUM WFC F814W none none none none 2 N/A ANY 6 WFC3/UVI ACCUM UVIS F814W none none none none 2 N/A S CVN-I-DSPH-1 7 ACS/WFC ACCUM WFC F814W none none none none 2 N/A ANY 8 WFC3/UVI ACCUM UVIS F814W none none none none 2 N/A S CVN-I-DSPH-1 9 ACS/WFC ACCUM WFC F814W none none none none 2 N/A ANY 10 WFC3/UVI ACCUM UVIS F814W none none none none 2 N/A S 15476( 4) - 14-Dec-2018 15:54:14 - [ 8] Visit: 03 Visit Requirements: ORIENT 1D TO 240 D; ORIENT 300D TO 359 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1269 S POS TARG 0.0, 0.0; PAR 2 2 (1269 S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS F606W 1 1229 S S see below (1320 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1260 S POS TARG 0.148, 0.086; 2 (1260 S) PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS F606W 1 1229 S S see below (1270 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 60 S (60 POS TARG 0.222, 0.240; 2 S) PAR 6 WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY WFC3/UVI ACCUM UVIS F606W FLASH=10 1 60 S (60 S S) ------------------------------------------------------------------------------------------------------------------------------------ 7 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1240 S POS TARG 0.222, 0.240; 2 (1240 S) PAR 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY WFC3/UVI ACCUM UVIS F606W 1 1230 S S see below (1250 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 CVN-I-DSPH- ACS/WFC ACCUM WFC F606W 1 1280 S POS TARG 0.074, 0.154; 2 (1280 S) PAR 10 WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY WFC3/UVI ACCUM UVIS F606W 1 1300 S S see below (1366 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CVN-I-DSPH-2 1 ACS/WFC ACCUM WFC F606W none none none none 1 N/A 15476( 4) - 14-Dec-2018 15:54:14 - [ 9] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ANY 2 WFC3/UVI ACCUM UVIS F606W none none none none 1 1320.0 S S CVN-I-DSPH-2 3 ACS/WFC ACCUM WFC F606W none none none none 1 N/A ANY 4 WFC3/UVI ACCUM UVIS F606W none none none none 1 1270.0 S S CVN-I-DSPH-2 5 ACS/WFC ACCUM WFC F606W none none none none 2 N/A ANY 6 WFC3/UVI ACCUM UVIS F606W none none none none 2 N/A S CVN-I-DSPH-2 7 ACS/WFC ACCUM WFC F606W none none none none 2 N/A ANY 8 WFC3/UVI ACCUM UVIS F606W none none none none 2 1250.0 S S CVN-I-DSPH-2 9 ACS/WFC ACCUM WFC F606W none none none none 2 N/A ANY 10 WFC3/UVI ACCUM UVIS F606W none none none none 2 1366.0 S S 15476( 4) - 14-Dec-2018 15:54:14 - [ 10] Visit: 04 Visit Requirements: SAME ORIENT AS 03 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1269 S POS TARG 0.0, 0.0; PAR 2 2 (1269 S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS F814W 1 1229 S S (1229 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1260 S POS TARG 0.148, 0.086; 2 (1260 S) PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS F814W 1 1229 S S (1229 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 60 S (60 POS TARG 0.222, 0.240; 2 S) PAR 6 WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY WFC3/UVI ACCUM UVIS F814W FLASH=10 1 60 S (60 S S) ------------------------------------------------------------------------------------------------------------------------------------ 7 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1240 S POS TARG 0.222, 0.240; 2 (1240 S) PAR 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY WFC3/UVI ACCUM UVIS F814W 1 1230 S S (1230 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 CVN-I-DSPH- ACS/WFC ACCUM WFC F814W 1 1280 S POS TARG 0.074, 0.154; 2 (1280 S) PAR 10 WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY WFC3/UVI ACCUM UVIS F814W 1 1300 S S (1300 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CVN-I-DSPH-2 1 ACS/WFC ACCUM WFC F814W none none none none 1 N/A ANY 2 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S CVN-I-DSPH-2 3 ACS/WFC ACCUM WFC F814W none none none none 1 N/A ANY 4 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S 15476( 4) - 14-Dec-2018 15:54:14 - [ 11] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CVN-I-DSPH-2 5 ACS/WFC ACCUM WFC F814W none none none none 2 N/A ANY 6 WFC3/UVI ACCUM UVIS F814W none none none none 2 N/A S CVN-I-DSPH-2 7 ACS/WFC ACCUM WFC F814W none none none none 2 N/A ANY 8 WFC3/UVI ACCUM UVIS F814W none none none none 2 N/A S CVN-I-DSPH-2 9 ACS/WFC ACCUM WFC F814W none none none none 2 N/A ANY 10 WFC3/UVI ACCUM UVIS F814W none none none none 2 N/A S 15476( 4) - 14-Dec-2018 15:54:14 - [ 12] Summary Form for Proposal 15476 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS, WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=10 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 15D TO 215 D, ORIENT 1D TO 240 D, ORIENT 270D TO 320 D, ORIENT 300D TO 359 D, PAR 10 WITH 9, PAR 2 WITH 1, PAR 4 WITH 3, PAR 6 WITH 5, PAR 8 WITH 7, POS TARG 0.0, 0.0, POS TARG 0.074, 0.154, POS TARG 0.148, 0.086, POS TARG 0.222, 0.240, SAME ORIENT AS 01, SAME ORIENT AS 03 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ANY, CVN-I-DSPH-1, CVN-I-DSPH-2 ------------------------------------------------------------------------------------------------------------------------------------