12544( 6) - 20-Mar-2012 17:12:19 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12544 Version: 6 Check-in Time: 20-Mar-2012 17:12:19 STScI Edit Number: 2 Title Confirming Ultra-cold (Teff < 500K) Brown Dwarf Suspects Identified with WISE ------------------------------------------------------------------------------------ Type Cycle GO 19 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Michael C. Cushing University of Toledo CoI: Dr. J. Davy Kirkpatrick California Institute of Technology N CoI: Dr. Christopher R. Gelino California Institute of Technology N CoI: Dr. Amanda K. Mainzer Jet Propulsion Laboratory N CoI: Mr. Roger L. Griffith Jet Propulsion Laboratory N CoI: Dr. Michael F. Skrutskie The University of Virginia N CoI: Dr. Kenneth A. Marsh California Institute of Technology N ------------------------------------------------------------------------------------ Abstract Despite the spectacular success of wide-field, sky surveys (2MASS, SDSS, and UKIDSS) in uncovering a large population of brown dwarfs in the solar neighborhood, a gap of nearly 400 K remains between the coolest brown dwarfs known (Teff ~ 500 K) and Jupiter (Teff ~ 128 K). Yet it is exactly these cold, low-mass brown dwarfs that are essential to measuring the functional form of the low-mass mass function and determining the lower mass limit of star formation. With atmospheric conditions similar to those of giant planets, cold brown dwarfs are also excellent proxies with which to test the ultracool model atmospheres that are critical to our understanding of exoplanets. One of the primary science goals of the Wide-field Infrared Survey Explorer (WISE), a NASA mission that recently completed a survey of the entire sky at four mid-infrared wavelengths, is to discover a large population of these cool brown dwarfs. As part of a larger followup campaign that involves both ground- and space-based observatories, we were awarded 12 orbits in Cycle 18 (as part of a Cycle 7 Spitzer program) to obtain near-infrared WFC3 grism spectroscopy of twelve of our faintest and reddest, and thus presumably coldest, brown dwarf candidates. We here propose to obtain spectra of an additional four objects that, along with the twelve Cycle 18 targets, constitute the best cold brown dwarf candidates that we have identified in roughly half of the sky. These objects are too faint for spectroscopic verification from the ground so HST/WFC3 observations are the only avenue for confirming their ultracool nature. ------------------------------------------------------------------------------------ Observations Description ------------------------ Proper spectral classification of T dwarfs requires spectra covering at least the 1.1?1.7 ?m wavelength range (see Figure 4). We will therefore use the G141 grism in WFC3 which provides a resolving power of ?/Æ? ?130 over the 1.1?1.7 ?m wavelength range to observe 4 WISE brown dwarf candidates with J > 19.5. We will also obtain F125W imaging of each source in order to establish the wavelength zero-point of the spectra and set the absolute flux level of the resulting spectra. Based on our previous experience with the spectral classification and modeling of late- type T dwarf spectra, we require a minimum S/N of 15 at the FWHM 12544( 6) - 20-Mar-2012 17:12:19 - [ 2] points of the J-band peak and a S/N of 20 for the direct images in order to absolutely flux calibrate the spectrum to 5%. We used the spectrum of the T8 standard 2MASS 0415?0935 and the WFC3 Exposure Time Calculator to estimate the exposure time required to reach the required S/N for each source. Including all overheads (guide star aquisition, instrument, dithers, and buffer dump) we can obtain the required S/N in a single orbit per object so in total we request 4 orbits. All observations will be dithered to aid with the removal of bad/hot pixels. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12544( 6) - 20-Mar-2012 17:12:19 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 WISE22096+27 STAR, T RA=22H09M5.7300S +/- 0.1", J2000 J=19.6 114 DEC=+27D11'44.00" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 WISE04102+15 STAR, T RA=04H10M22.7200S +/- 0.1", J2000 J=19.5 024 DEC=+15D02'48.55" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 4 WISE09430+36 STAR, T RA=09H43M5.9900S +/- 0.1", J2000 J=19.8 072 DEC=+36D07'23.55" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 6 WISE05351-75 STAR, T RA=05H35M16.8100S +/- 0.5", J2000 V = 35 +/- 5 002 DEC=-75D00'25.27" +/- 0.5" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 12544( 6) - 20-Mar-2012 17:12:19 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 12544( 6) - 20-Mar-2012 17:12:19 - [ 5] Visit: 01 Visit Requirements: ORIENT 282D TO 282 D On Hold Comments: Additional Comments: WISE 0535-75002 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WISE05351-7 WFC3/IR MULTIAC GRISM1024 F140W SAMP-SEQ=SPARS25, NSAMP=4 1 DEF PATTERN 1 1 5002 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 WISE05351-7 WFC3/IR MULTIAC GRISM1024 G141 SAMP-SEQ=SPARS50, NSAMP=12 1 DEF PATTERN 1 2 5002 CUM ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ WISE05351-75002 1 WFC3/IR MULTIAC GRISM102 F140W 1 none none none 1 N/A CUM 4 WISE05351-75002 1 WFC3/IR MULTIAC GRISM102 F140W 2 none none none 1 N/A CUM 4 WISE05351-75002 1 WFC3/IR MULTIAC GRISM102 F140W 3 none none none 1 N/A CUM 4 WISE05351-75002 1 WFC3/IR MULTIAC GRISM102 F140W 4 none none none 1 N/A CUM 4 WISE05351-75002 2 WFC3/IR MULTIAC GRISM102 G141 1 none none none 1 N/A CUM 4 WISE05351-75002 2 WFC3/IR MULTIAC GRISM102 G141 2 none none none 1 N/A CUM 4 WISE05351-75002 2 WFC3/IR MULTIAC GRISM102 G141 3 none none none 1 N/A CUM 4 WISE05351-75002 2 WFC3/IR MULTIAC GRISM102 G141 4 none none none 1 N/A CUM 4 12544( 6) - 20-Mar-2012 17:12:19 - [ 6] Visit: 02 Visit Requirements: ORIENT 12D TO 18 D; ORIENT 39D TO 43 D; ORIENT 88D TO 90 D; ORIENT 96D TO 100 D; ORIENT 168D TO 172 D; ORIENT 192D TO 198 D; ORIENT 219D TO 223 D; ORIENT 268D TO 270 D; ORIENT 276D TO 280 D; ORIENT 348D TO 352 D On Hold Comments: Additional Comments: WISE 04102+15024 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WISE04102+1 WFC3/IR MULTIAC GRISM1024 F140W SAMP-SEQ=SPARS25, NSAMP=4 1 DEF PATTERN 1 1 5024 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 WISE04102+1 WFC3/IR MULTIAC GRISM1024 G141 SAMP-SEQ=SPARS50, NSAMP=11 1 DEF PATTERN 1 2 5024 CUM ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ WISE04102+15024 1 WFC3/IR MULTIAC GRISM102 F140W 1 none none none 1 N/A CUM 4 WISE04102+15024 1 WFC3/IR MULTIAC GRISM102 F140W 2 none none none 1 N/A CUM 4 WISE04102+15024 1 WFC3/IR MULTIAC GRISM102 F140W 3 none none none 1 N/A CUM 4 WISE04102+15024 1 WFC3/IR MULTIAC GRISM102 F140W 4 none none none 1 N/A CUM 4 WISE04102+15024 2 WFC3/IR MULTIAC GRISM102 G141 1 none none none 1 N/A CUM 4 WISE04102+15024 2 WFC3/IR MULTIAC GRISM102 G141 2 none none none 1 N/A CUM 4 WISE04102+15024 2 WFC3/IR MULTIAC GRISM102 G141 3 none none none 1 N/A CUM 4 WISE04102+15024 2 WFC3/IR MULTIAC GRISM102 G141 4 none none none 1 N/A CUM 4 12544( 6) - 20-Mar-2012 17:12:19 - [ 7] Visit: 03 Visit Requirements: ORIENT 8D TO 12 D; ORIENT 37D TO 46 D; ORIENT 71D TO 74 D; ORIENT 81D TO 85 D; ORIENT 149D TO 152 D; ORIENT 188D TO 192 D; ORIENT 217D TO 226 D; ORIENT 251D TO 254 D; ORIENT 261D TO 265 D; ORIENT 329D TO 332 D On Hold Comments: Additional Comments: WISE 09430+36072 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WISE09430+3 WFC3/IR MULTIAC GRISM1024 F140W SAMP-SEQ=SPARS25, NSAMP=5 1 DEF PATTERN 1 1 6072 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 WISE09430+3 WFC3/IR MULTIAC GRISM1024 G141 SAMP-SEQ=SPARS50, NSAMP=11 1 DEF PATTERN 1 2 6072 CUM ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ WISE09430+36072 1 WFC3/IR MULTIAC GRISM102 F140W 1 none none none 1 N/A CUM 4 WISE09430+36072 1 WFC3/IR MULTIAC GRISM102 F140W 2 none none none 1 N/A CUM 4 WISE09430+36072 1 WFC3/IR MULTIAC GRISM102 F140W 3 none none none 1 N/A CUM 4 WISE09430+36072 1 WFC3/IR MULTIAC GRISM102 F140W 4 none none none 1 N/A CUM 4 WISE09430+36072 2 WFC3/IR MULTIAC GRISM102 G141 1 none none none 1 N/A CUM 4 WISE09430+36072 2 WFC3/IR MULTIAC GRISM102 G141 2 none none none 1 N/A CUM 4 WISE09430+36072 2 WFC3/IR MULTIAC GRISM102 G141 3 none none none 1 N/A CUM 4 WISE09430+36072 2 WFC3/IR MULTIAC GRISM102 G141 4 none none none 1 N/A CUM 4 12544( 6) - 20-Mar-2012 17:12:19 - [ 8] Visit: 04 Visit Requirements: ORIENT 13D TO 15 D; ORIENT 40D TO 41 D; ORIENT 46D TO 47 D; ORIENT 51D TO 52 D; ORIENT 135D TO 136 D; ORIENT 141D TO 142 D; ORIENT 193D TO 195 D; ORIENT 220D TO 221 D; ORIENT 226D TO 227 D; ORIENT 231D TO 232 D; ORIENT 315D TO 316 D; ORIENT 321D TO 322 D On Hold Comments: Additional Comments: WISE 22094+27114 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WISE22096+2 WFC3/IR MULTIAC GRISM1024 F140W SAMP-SEQ=SPARS25, NSAMP=4 1 DEF PATTERN 1 1 7114 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 WISE22096+2 WFC3/IR MULTIAC GRISM1024 G141 SAMP-SEQ=SPARS50, NSAMP=11 1 DEF PATTERN 1 2 7114 CUM ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ WISE22096+27114 1 WFC3/IR MULTIAC GRISM102 F140W 1 none none none 1 N/A CUM 4 WISE22096+27114 1 WFC3/IR MULTIAC GRISM102 F140W 2 none none none 1 N/A CUM 4 WISE22096+27114 1 WFC3/IR MULTIAC GRISM102 F140W 3 none none none 1 N/A CUM 4 WISE22096+27114 1 WFC3/IR MULTIAC GRISM102 F140W 4 none none none 1 N/A CUM 4 WISE22096+27114 2 WFC3/IR MULTIAC GRISM102 G141 1 none none none 1 N/A CUM 4 WISE22096+27114 2 WFC3/IR MULTIAC GRISM102 G141 2 none none none 1 N/A CUM 4 WISE22096+27114 2 WFC3/IR MULTIAC GRISM102 G141 3 none none none 1 N/A CUM 4 WISE22096+27114 2 WFC3/IR MULTIAC GRISM102 G141 4 none none none 1 N/A CUM 4 12544( 6) - 20-Mar-2012 17:12:19 - [ 9] Summary Form for Proposal 12544 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures GRISM1024 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=11, NSAMP=12, NSAMP=4, NSAMP=5, SAMP-SEQ=SPARS25, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 12D TO 18 D, ORIENT 135D TO 136 D, ORIENT 13D TO 15 D, ORIENT 141D TO 142 D, ORIENT 149D TO 152 D, ORIENT 168D TO 172 D, ORIENT 188D TO 192 D, ORIENT 192D TO 198 D, ORIENT 193D TO 195 D, ORIENT 217D TO 226 D, ORIENT 219D TO 223 D, ORIENT 220D TO 221 D, ORIENT 226D TO 227 D, ORIENT 231D TO 232 D, ORIENT 251D TO 254 D, ORIENT 261D TO 265 D, ORIENT 268D TO 270 D, ORIENT 276D TO 280 D, ORIENT 282D TO 282 D, ORIENT 315D TO 316 D, ORIENT 321D TO 322 D, ORIENT 329D TO 332 D, ORIENT 348D TO 352 D, ORIENT 37D TO 46 D, ORIENT 39D TO 43 D, ORIENT 40D TO 41 D, ORIENT 46D TO 47 D, ORIENT 51D TO 52 D, ORIENT 71D TO 74 D, ORIENT 81D TO 85 D, ORIENT 88D TO 90 D, ORIENT 8D TO 12 D, ORIENT 96D TO 100 D, PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140W, G141 ------------------------------------------------------------------------------------------------------------------------------------ Target Names WISE04102+15024, WISE05351-75002, WISE09430+36072, WISE22096+27114 ------------------------------------------------------------------------------------------------------------------------------------