13383( 4) - 28-Jun-2013 16:00:22 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13383 Version: 4 Check-in Time: 28-Jun-2013 16:00:22 STScI Edit Number: 1 Title Measuring the Properties of Dwarf Streams ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Mary E. Putman Columbia University in the City of New Y York CoI: Mr. Joo Heon Yoon Columbia University in the City of New N York CoI: Dr. Jessica Werk University of California - Santa Cruz N CoI: Dr. Gurtina Besla Columbia University in the City of New N York ------------------------------------------------------------------------------------ Abstract We propose to measure the metallicity and ionization conditions of a gaseous stream trailing behind a pair of dwarf galaxies in the local universe. The NGC 4532/DDO 137 system is a clear analog to the Milky Way's massive satellite galaxies, the Large and Small Magellanic Clouds; however, this system is not in close proximity to a massive spiral galaxy. Furthermore, it is the only other dwarf stream for which the metallicity and ionization conditions can be directly measured due to the fortuitous alignment of a bright background QSO with the HI stream. We will use the data to examine the properties and formation mechanisms of such streams and how they differ with environment. Such information can be used to develop a method to discriminate between cold accreting filaments and streams stripped from low mass galaxies at all redshifts. ------------------------------------------------------------------------------------ Observations Description ------------------------ These observations of the QSO probe on the HI stream will use COS in medium resolution mode using the G130M/G160M gratings to obtain the metallicity and ionization conditions of the stream. With COS/G130M and G160M spectra, we will cover a wavelength range of 1150-1775 AA, where Ly-alpha and key strong metal transitions are accessible (OI, CII, CIV, SiII, SiIII, SiIV, NV). The observations will yield moderate S/N ~ 15, high resolution (~15 km/s) spectra for both gratings. The combination of resolution and signal-to-noise is designed to allow us to detect weak Ly-alpha and metal absorption features, W > 50 AA, at 5-sigma (at 1215 AA and 1550 AA, Ly-alpha and CIV, respectively). The sightline was chosen from the Veron-Cetty QSO catalog 13th ed., and cross-matching it with the GALEX database. The GALEX data provide an estimate of the UV flux, with the FUV imaging band covering the range 1344 - 1786 AA (effective wavelength 1516 AA). This GALEX selection has proven to be highly successful, and ensures bright object protection screening. The SDSS images were checked to ensure there were no obvious stars or galaxies interfering with the GALEX flux. 13383( 4) - 28-Jun-2013 16:00:22 - [ 2] We have an a priori expectation from 21-cm HI maps that we will probe N_HI > 10^(18.5) cm^(-2) gas, covering a wide range of absorption lines, similar to those seen in extra-galactic damped Ly-alpha systems. This background probe is also serendipitously bright (m_{FUV}=17.3), allowing us to obtain both G130M and G160M data in only 8 orbits. With sufficient separation from the MW Ly-alpha absorption, damping wings in the Ly-alpha profile will allow us to obtain the necessary HI column density, but as noted we already have a limit on this from the emission line observations. Our previous observations (Yoon et al. 2012), also show we will easily resolve numerous absorbers along a sightline. The acquisition strategy (mirror A vs B) has been chosen using the COS Imaging Acquisition ETC and the Galex FUV fluxes to normalise a variety of input spectra (both flat spectra, and QSO spectra redshifted to the measured QSO redshift). To be conservative, we chose the longest suggested exposure time among the various results, while ensuring count-rate limits are not exceeded. Science exposure times were estimated with the COS spectroscopy ETC. They were broken up to cover two central wavelengths and multiple FP-POS and extended to fully pack the orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 13383( 4) - 28-Jun-2013 16:00:22 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ123235. GALAXY, QSO RA=12H32M35.8200S +/- 0.1", J2000 V = 16.57 m_FUV=17.31 82+060310.0 DEC=+06D03'9.97" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 13383( 4) - 28-Jun-2013 16:00:22 - [ 4] Visit: 01 Visit Requirements: 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 SDSSJ123235 COS/NUV ACQ/IMA PSA MIRRORB 1 42.9 S GS ACQ SCENARIO BASE1B3 .82+060310. GE (42.9 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ123235 COS/FUV TIME-TA PSA G130M 1291 FP-POS=1, BUFFER-TIME=2985 1 1157 S .82+060310. G (1157 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ123235 COS/FUV TIME-TA PSA G130M 1291 FP-POS=2, BUFFER-TIME=2985 1 1157 S .82+060310. G (1157 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ123235 COS/FUV TIME-TA PSA G130M 1309 FP-POS=3, BUFFER-TIME=3105 1 1402 S .82+060310. G (1402 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ123235 COS/FUV TIME-TA PSA G130M 1309 FP-POS=4, BUFFER-TIME=3105 1 1402 S .82+060310. G (1402 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 6 SDSSJ123235 COS/FUV TIME-TA PSA G160M 1589 FP-POS=1, BUFFER-TIME=8644 1 2900 S .82+060310. G see below 0 (2945 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 SDSSJ123235 COS/FUV TIME-TA PSA G160M 1589 FP-POS=2, BUFFER-TIME=8644 1 2900 S .82+060310. G see below 0 (2947 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ123235.82+0603 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 10.0 GE SDSSJ123235.82+0603 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 10.0 G SDSSJ123235.82+0603 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 10.0 G SDSSJ123235.82+0603 4 COS/FUV TIME-TA PSA G130M 1309 none none none none 2 N/A 10.0 G 13383( 4) - 28-Jun-2013 16:00:22 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ123235.82+0603 5 COS/FUV TIME-TA PSA G130M 1309 none none none none 2 N/A 10.0 G SDSSJ123235.82+0603 6 COS/FUV TIME-TA PSA G160M 1589 none none none none 3 2945.0 S 10.0 G SDSSJ123235.82+0603 7 COS/FUV TIME-TA PSA G160M 1589 none none none none 4 2947.0 S 10.0 G 13383( 4) - 28-Jun-2013 16:00:22 - [ 6] Visit: 02 Visit Requirements: 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 SDSSJ123235 COS/NUV ACQ/IMA PSA MIRRORB 1 42.9 S GS ACQ SCENARIO BASE1B3 .82+060310. GE (42.9 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ123235 COS/FUV TIME-TA PSA G160M 1589 FP-POS=1, BUFFER-TIME=8644 1 2400 S .82+060310. G see below 0 (2414 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ123235 COS/FUV TIME-TA PSA G160M 1611 FP-POS=2, BUFFER-TIME=9274 1 2900 S .82+060310. G see below 0 (2947 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ123235 COS/FUV TIME-TA PSA G160M 1611 FP-POS=3, BUFFER-TIME=9274 1 2900 S .82+060310. G see below 0 (2947 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ123235 COS/FUV TIME-TA PSA G160M 1611 FP-POS=4, BUFFER-TIME=9274 1 2900 S .82+060310. G see below 0 (2947 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ123235.82+0603 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 10.0 GE SDSSJ123235.82+0603 2 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 2414.0 S 10.0 G SDSSJ123235.82+0603 3 COS/FUV TIME-TA PSA G160M 1611 none none none none 2 2947.0 S 10.0 G SDSSJ123235.82+0603 4 COS/FUV TIME-TA PSA G160M 1611 none none none none 3 2947.0 S 10.0 G SDSSJ123235.82+0603 5 COS/FUV TIME-TA PSA G160M 1611 none none none none 4 2947.0 S 10.0 G 13383( 4) - 28-Jun-2013 16:00:22 - [ 7] Summary Form for Proposal 13383 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=2985, BUFFER-TIME=3105, BUFFER-TIME=8644, BUFFER-TIME=9274, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ123235.82+060310.0 ------------------------------------------------------------------------------------------------------------------------------------