10168( 3) - 05/20/04 09:29 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10168 Version: 3 Check-in Date: 20-May-2004 13:27:39 1.Proposal Title: Spatially Resolved Spectroscopy of HR 4796A's Dust Ring ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 13 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Alycia J. Weinberger Carnegie Institution of Washington CoI: Dr. Aki Roberge Carnegie Institution of Washington N CoI: Dr. Eliot Malumuth Science Systems and Applications, Inc. N CoI: Dr. Glenn Schneider University of Arizona N CoI: Dr. Alfred Schultz Space Telescope Science Institute N CoI: Dr. Murray Silverstone University of Arizona N CoI: Dr. Dean C. Hines Space Science Institute N ------------------------------------------------------------------------------------ 6. Abstract HST's high-contrast capabilities provide exciting imaging of circumstellar debris disks with complex structures. In particular, broad-band imaging using the coronagraphs in NICMOS and STIS has elucidated the disk morphology of HR 4796A exquisitely, but can only provide colors, not detailed compositional information on its dust. With spectra, we will measure the detailed albedo of the disk dust over a large wavelength range and search for interstellar medium-like molecules and water ice. We will also use our spatially resolved spectra for very high angular resolution profiles of the disk width to constrain models for planets circling inside the dust. We have demonstrated in a previous program how to use STIS for spatially resolved disk spectroscopy. We now propose to use our technique to study HR 4796A. ------------------------------------------------------------------------------------ 10168( 3) - 05/20/04 09:29 - [ 2] Observations Description ------------------------ Set of Exposures to Be Performed on HR4796A and a PSF Star : 1) Target aquisition. 2) Peak-up in spatial and spectral directions to precisely determine star location -- required for accurate centering under the fiducial bar. 3) Point-source G750L and G430L spectra taken with the 52X0.2 slit (no fiducial bar) to exactly measure the stellar spectrum -- required for accurate color matching of PSF to target star before PSF subtraction. 4) G750L CCD lamp flat -- required for defringing of STIS CCD data longward of 7500 A. 5) G750L and G430L spectra taken with the 52X0.2F2 slit, star centered under the 0."86 wide fiducial bar -- bar required to reduce the amount of instrumentally scattered stellar light. Real Time Justification ----------------------- NONE Calibration Justification ------------------------- 1) Due to the limited number of PSF observations taken using the STIS fiducial bar, we included time for PSF observations in our phase 1 proposal. The PSF star is brighter than our target star, so it requires less integration time although observed with the same scheme as the target star. 2) For all observations with the G750L grating, we require contemporaneous CCDFLATs for defringing. Additional Comments ------------------- The tight ORIENT constraint puts the slit parallel to the semi-major axis of the inclined HR4796 disk, in order to maximize the amount of disk flux entering the spectrograph and allow good PSF subtraction. ------------------------------------------------------------------------------------ 10168( 3) - 05/20/04 09:29 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HR4796A STAR, A0-A3 V-IV, RA=12H36M1.07S +/- 0.1", DEC=- J2000 V = 5.78 PROTOPLANETARY DISK 39D52'10.0" +/- 0.1" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.00486 -0.024 0.01491 2 HR4748-PSF STAR, B6-B9.5 V-IV RA=12H28M22.49S +/- 0.1", DEC=- J2000 V = 5.45 39D02'28.1" +/- 0.1" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.0025 -0.014 0.00764 10168( 3) - 05/20/04 09:29 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 71.1D TO 73.1 D; ORIENT 251.1D TO 253.1 D; GROUP 01, 02 WITHIN 4.0 Orbits On Hold Comments: Additional Comments: Point-source and fiducial spectra of HR4796A with G705L and G430L. Need to align slit parallel to disk semi-major axis. Disk PA = 27.1 degrees. ORIENT = (27.1, 207.1) + offset angle = (27.1, 207.1) + 45 = (72.1, 252.1) degrees +/- 1.0 degrees. Visits 01 and 02 should be scheduled as close together in time as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HR4796A STIS/CCD ACQ F28X50OII MIRROR ACQTYPE=POINT 1 0.1 S Comments: F28X50OII filter gives S/N = 137 in 0.1s and doesn't saturate (with F28X50LP, brightest pixel saturates in minimum exposure time). ------------------------------------------------------------------------------------------------------------------------------------ 2 HR4796A STIS/CCD ACQ/PEA 0.2X0.05N MIRROR 1 0.2 S K D Comments: Peak-up in x and y required for accurate positioning of star under fiducial bar (short slit peak-up). T_exp = 0.2s with 0.2X0.05ND gives S/N = 246 and does not saturate. ------------------------------------------------------------------------------------------------------------------------------------ 3 HR4796A STIS/CCD ACCUM 52X0.2 G430L 4300 GAIN=1,CR-SPLIT=2 1 0.2 S Comments: Star will not saturate in minimum exposure time (0.1s) and S/N > 30 achieved at all wavelengths. ------------------------------------------------------------------------------------------------------------------------------------ 4 HR4796A STIS/CCD ACCUM 52X0.2F2 G430L 4300 GAIN=1,CR-SPLIT=2 1 1732 S Comments: Brightest pixel in 866s = 866s x 16.7 counts/pix/s = 14462 = 44% full well at GAIN=1. Maximum count rate estimated from 52X0.2F2 observation of HD141653 (A0V star, V = 5.194, file o68m01050_crj.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 HR4796A STIS/CCD ACCUM 52X0.2 G750L 7751 GAIN=1,CR-SPLIT=2 1 0.2 S Comments: Star will not saturate in minimum exposure time (0.1s) and S/N > 30 achieved at all wavelengths. ------------------------------------------------------------------------------------------------------------------------------------ 6 CCDFLAT STIS/CCD ACCUM 52X0.2 G750L 7751 2 DEF Comments: CCDFLAT taken with 52X0.2 slit for better defringing of extended-source spectra (narrower slit would be better for defringing point-source spectra). Do 2 iterations for cosmic-ray rejection. ------------------------------------------------------------------------------------------------------------------------------------ 10168( 3) - 05/20/04 09:29 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 7 HR4796A STIS/CCD ACCUM 52X0.2F2 G750L 7751 GAIN=1,CR-SPLIT=4 1 2416.8 S Comments: Brightest pixel in 604.2s = 604.2s x 28.9 counts/pix/s = 17461 = 53% full well at GAIN=1. Maximum count rate estimated from 52X0.2F2 observation of HD141653 (A0V star, V = 5.194, file o68m010b0_crj.fits). ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 none none none none 1 tbd 01 2 none none none none 1 tbd 01 3 none none none 1 1 tbd 01 3 none none none 2 1 tbd 01 4 none none none 1 1 tbd 01 4 none none none 2 1 tbd 01 5 none none none 1 2 tbd 01 5 none none none 2 2 tbd 01 6 none none 1 none 2 tbd 01 6 none none 2 none 2 tbd 01 7 none none none 1 2 tbd 01 7 none none none 2 2 tbd 01 7 none none none 3 2 tbd 01 7 none none none 4 2 tbd 10168( 3) - 05/20/04 09:29 - [ 6] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Point-source and fiducial spectra of HR4748-PSF with G705L and G430L. Have to start a new visit since the angle between HR4796 and HD4748 is 1.6 degrees. No orientation constraint for observations. Visits 01 and 02 should be scheduled as close together as possible (GROUP WITHIN constraint given on visit 01). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HR4748-PSF STIS/CCD ACQ F28X50OII MIRROR ACQTYPE=POINT 1 0.1 S Comments: F28X50OII filter gives S/N = 160 to 197 in 0.1s and doesn't saturate (with F28X50LP, brightest pixel saturates in minimum exposure time). ------------------------------------------------------------------------------------------------------------------------------------ 2 HR4748-PSF STIS/CCD ACQ/PEA 0.2X0.05N MIRROR 1 0.2 S K D Comments: Peak-up in x and y required for accurate positioning of star under fiducial bar (short slit peak-up). T_exp = 0.2s with 0.2X0.05ND gives S/N = 287 to 300 and does not saturate. ------------------------------------------------------------------------------------------------------------------------------------ 3 HR4748-PSF STIS/CCD ACCUM 52X0.2 G430L 4300 GAIN=1,CR-SPLIT=2 1 0.2 S Comments: Star will not saturate in minimum integration time (0.1s) and S/N > 30 achieved at all wavelengths. ------------------------------------------------------------------------------------------------------------------------------------ 4 HR4748-PSF STIS/CCD ACCUM 52X0.2F2 G430L 4300 GAIN=1,CR-SPLIT=2 1 456 S Comments: PSF star is 0.33 mag = 1.355 times brighter than HR4796. Brightest pixel in 228s image = 228s x 22.6 counts/pix/s = 5152.8 = 16% full well at GAIN=1. Maximum count rate estimated from 52X0.2F2 observation of HD141653 (A0V star, V = 5.194, file o68m01050_crj.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 HR4748-PSF STIS/CCD ACCUM 52X0.2 G750L 7751 GAIN=1,CR-SPLIT=2 1 0.2 S Comments: Star will not saturate in minimum integration time (0.1s) and S/N > 30 achieved at all wavelengths. ------------------------------------------------------------------------------------------------------------------------------------ 10168( 3) - 05/20/04 09:29 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 CCDFLAT STIS/CCD ACCUM 52X0.2 G750L 7751 2 DEF Comments: CCDFLAT taken with 52X0.2 slit for better defringing of extended-source spectra (narrower slit would be better for defringing point-source spectra). Do 2 iterations for cosmic-ray rejection. ------------------------------------------------------------------------------------------------------------------------------------ 7 HR4748-PSF STIS/CCD ACCUM 52X0.2F2 G750L 7751 GAIN=1,CR-SPLIT=2 1 638 S Comments: PSF star is 0.33 mag = 1.355 times brighter than HR4796. Brightest pixel in 319s image = 319s x 38.9 counts/pix/s = 12409 = 38% full well at GAIN=1. Maximum count rate estimated from 52X0.2F2 observation of HD141653 (A0V star, V = 5.194, file o68m010b0_crj.fits). ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 02 1 none none none none 1 tbd 02 2 none none none none 1 tbd 02 3 none none none 1 1 tbd 02 3 none none none 2 1 tbd 02 4 none none none 1 1 tbd 02 4 none none none 2 1 tbd 02 5 none none none 1 1 tbd 02 5 none none none 2 1 tbd 02 6 none none 1 none 1 tbd 02 6 none none 2 none 1 tbd 02 7 none none none 1 1 tbd 02 7 none none none 2 1 tbd 10168( 3) - 05/20/04 09:29 - [ 8] Summary Form for Proposal 10168 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50OII 0.2X0.05ND 52X0.2 52X0.2F2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=2 GAIN=1 CR-SPLIT=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 71.1D TO 73.1 D; ORIENT 251.1D TO 253.1 D; GROUP 01, 02 WITHIN 4.0 Orbits ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430L G750L ------------------------------------------------------------------------------------------------------------------------------------ Target Names HR4796A CCDFLAT HR4748-PSF ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4300 7751 ------------------------------------------------------------------------------------------------------------------------------------