8789( 4) - 04/26/00 16:39 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8789 Version: 4 Check-in Date: 26-Apr-2000 16:37:56 1.Proposal Title: Probing the Outskirts of an Extrasolar Planet: Photometry and Spectroscopy ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO/DD 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Timothy Brown University Corporation For Atmospheric Research CoI: Dr. Adam Burrows University of Arizona N CoI: Dr. David Charbonneau Harvard University N CoI: Dr. Ronald L. Gilliland Space Telescope Science Institute Y CoI: Dr. Robert W. Noyes Harvard University N ------------------------------------------------------------------------------------ 5. Abstract HD 209458 is the first extrasolar planet known to transit the disk of its parent star. HST can provide unique probes of this system for moons, rings and atmospheric composition that are unlikely to be feasible with ground-based observations. Furthermore, we note that since HD 209458 will come out of the solar avoidance zone in mid- April 2000, it will be observable to HST several months before the first decent transits can be followed from the ground. The field of extrasolar planets is one that proceeds with breakneck speed (the entire field is only four years old), and next fall HD 209458 will no doubt be the subject of intensive study. The analysis of the data acquired by this project may be critically important in its own right, and should help significantly to define optimum follow-on observations during the coming year. Timely analysis and publication of the data will clearly be a top priority to the authors of this proposal. HST is thus in a unique position to deliver a wealth of science on this first transiting extrasolar planet early next year. ------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 2] Observations Description ------------------------ The combined technical goals of high precision time series photometry and high signal to noise spectroscopy in and out of transits are simultaneously satisfied by obtaining spectra with the STIS/CCD using the 580.8-638.0 nm setting of G750M. We plan to use the 2 arcsec slit to produce the optimal photometry, which is the primary objective of our proposal. This may result in a small degradation of the spectroscopic resolution, and thus affect our secondary objective, but this should not be an important factor since the alkali metal lines and molecular bands we aim to observe will be broad features. A 60s exposure for the V = 7.65 G0 star HD209458 will yield a peak count level of 51, 000 e-, a S/N per resolution element of 500 over the regions near the Sodium D lines of most interest (near 590 nm), and a total count level of just over 1.6e8 e- which will support time series S/N at a Poisson limit over 10, 000 per readout. Exposures would be cycled every 80s using a subarray of 64 pixels in cross-dispersion. Each HST orbital visibility period (excluding guide star acq or re-acq and occultation) for HD 209458 (RA 22 03 10.77, DEC +18 53 03.5 (2000)) will consist of about 48 minutes, during which 36 spectra with the above characteristics will be obtained. We expect a total of about 20 orbits x 36 exposures per orbit = 720 points in the times series photometry. About 180 of these will be during the inner transit (planet fully on stellar disk), about 82 during planet ingress and egress phases, with the remainder outside of transit. This will yield a Poission limited S/N for the co-added spectra per resolution element of about (250)^(1/2)x500 = 7900 inside transits and (460)^(1/2)x500 = 10700 outside transits. As described above, we have modeled the predicted absorption spectrum: a potentially prominent feature will be the sodium D lines, which should have an amplitude of 1 part in 1000 and a combined width of 2 nm, and thus be detected (or excluded) with a high degree of confidence. Co-adding the pixels of each individually observed spectrum will put our photometric precision at better than 1 part in 10, 000, which will allow us to detect the potential satellites and/or ring structures described above. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- At an expected orbital period in April 2000 of about 96.43 minutes a transit of HD 209458 spans about 1.87 orbits (outer contact points) and 1.33 orbits (inner contact). HD 209458 b has an orbital period P = 3.52433 days, and a time at the center of the transit T_c = 2451430.824 HJD. Satellites of HD 209458 could yield contact times as much as about 0.8 HST orbits before or after the planet ingress and egress times. Therefore we wish to schedule SAA-free orbital blocks of 5 orbits for which the HD 209458 transit will be within 50 minutes of the center of the block. Four such blocks will yield good sampling of times outside the transit, inside the transit and during the times for which satellite ingress and egress could be seen. Since the HD209458 orbital period is 3.52433 days, if a near center SAA-free visit is located for scheduling, then the same will hold at plus and minus a few 7 day intervals (two transit periods). We propose obtaining four visits each of 5 orbits at successive 7 day periods. Since there are 105.26 HST orbital periods in 2 HD 209458 transit periods, observing for four successive visits separated by about 7 days will yield essentially complete phase coverage (with nearly 100% redundancy) of the 8 hour interval centered on the planet transit. The minimum number of orbits to achieve the scientific goals proposed here is three visits of 5 orbits each, and if our request of 20 orbits is too great to be accomodated, we ask that a program consisting of 15 orbits be considered. However, with only three visits of five orbits, there will be several 24 minute portions of the light curve which will be sampled only once. The photometric changes caused by planetary satellites would, in general, occur at different places in the phase curve as the satellite moves in its orbit. Thus, it is necessary that as much of the phase curve as possible be sampled redundantly so that the subsequent interpretation may be unambiguous. Note: Strictly SAA free time was not granted and we now allow observations each 3.5 days within a six week window. ------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD209458 STAR, G V-IV RA=22H 3M 10.78S +/- 0.01S, J2000 V = 7.65+/-0.05 DEC=18D 53' 3.5" +/- 0.1" B-V = 0.594 Coordinate Source: Comments: Extrasolar planet host star. Coords from Hipp. Input Cat. SAO, GSC within 0.4" 8789( 4) - 04/26/00 16:39 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PERIOD 3.524736 D AND ZERO-PHASE JD2451497.796000 BETWEEN 16-Apr-2000 AND 27-May-2000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD209458 STIS/C ACQ F28X50O MIRROR 1 5.0 S PHASE 0.943 TO 0.963 CD II Comments: CCD peak counts expected are 69, 600 e- ------------------------------------------------------------------------------------------------------------------------------------ 2 WAVE STIS/C ACCUM 52X0.2 G750M 6094 1 DEF CD Comments: Explicit WAVECAL, auto-waves disabled ------------------------------------------------------------------------------------------------------------------------------------ 3 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64 27 60 S MAX DUR 100% CD Comments: Expected peak count level = 50, 800 e-, sum 1.65e8 e- ------------------------------------------------------------------------------------------------------------------------------------ 4 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64, 144 60 S MAX DUR 100% CD WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PERIOD 3.524736 D AND ZERO-PHASE JD2451497.796000 SAME ORIENT AS 01 BETWEEN 16-Apr-2000 AND 27-May-2000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD209458 STIS/C ACQ F28X50O MIRROR 1 5.0 S PHASE 0.943 TO 0.963 CD II Comments: CCD peak counts expected are 69, 600 e- ------------------------------------------------------------------------------------------------------------------------------------ 2 WAVE STIS/C ACCUM 52X0.2 G750M 6094 1 DEF CD Comments: Explicit WAVECAL, auto-waves disabled ------------------------------------------------------------------------------------------------------------------------------------ 3 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64 27 60 S MAX DUR 100% CD ------------------------------------------------------------------------------------------------------------------------------------ 4 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64, 144 60 S MAX DUR 100% CD WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 7] Visit: 03 Visit Priority: Visit Requirements: PERIOD 3.524736 D AND ZERO-PHASE JD2451497.796000 SAME ORIENT AS 01 BETWEEN 16-Apr-2000 AND 27-May-2000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD209458 STIS/C ACQ F28X50O MIRROR 1 5.0 S PHASE 0.943 TO 0.963 CD II Comments: CCD peak counts expected are 69, 600 e- ------------------------------------------------------------------------------------------------------------------------------------ 2 WAVE STIS/C ACCUM 52X0.2 G750M 6094 1 DEF CD Comments: Explicit WAVECAL, auto-waves disabled ------------------------------------------------------------------------------------------------------------------------------------ 3 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64, 27 60 S MAX DUR 100% POS TARG CD CENTERAXIS2=517 0.000, 1.000 ------------------------------------------------------------------------------------------------------------------------------------ 4 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64, 144 60 S MAX DUR 100% POS TARG CD WAVECAL=NO,CENTERAXIS2=517 0.000, 1.000 ------------------------------------------------------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 8] Visit: 04 Visit Priority: Visit Requirements: PERIOD 3.524736 D AND ZERO-PHASE JD2451497.796000 SAME ORIENT AS 01 BETWEEN 16-Apr-2000 AND 27-May-2000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD209458 STIS/C ACQ F28X50O MIRROR 1 5.0 S PHASE 0.943 TO 0.963 CD II Comments: CCD peak counts expected are 69, 600 e- ------------------------------------------------------------------------------------------------------------------------------------ 2 WAVE STIS/C ACCUM 52X0.2 G750M 6094 1 DEF CD Comments: Explicit WAVECAL, auto-waves disabled ------------------------------------------------------------------------------------------------------------------------------------ 3 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64, 27 60 S MAX DUR 100% POS TARG CD CENTERAXIS2=517 0.000, 1.000 ------------------------------------------------------------------------------------------------------------------------------------ 4 HD209458 STIS/C ACCUM 52X2 G750M 6094 GAIN=4,CR-SPLIT=NO,SIZEAXIS2=64, 144 60 S MAX DUR 100% POS TARG CD WAVECAL=NO,CENTERAXIS2=517 0.000, 1.000 ------------------------------------------------------------------------------------------------------------------------------------ 8789( 4) - 04/26/00 16:39 - [ 9] Summary Form for Proposal 8789 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50OII 52X0.2 52X2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters GAIN=4 CR-SPLIT=NO SIZEAXIS2=64 WAVECAL=NO CENTERAXIS2=517 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 3.524736 D AND ZERO-PHASE JD2451497.796000 BETWEEN 16-Apr-2000 AND 27-May-2000 PHASE 0.943 TO 0.963 MAX DUR 100% PERIOD 3.524736 D AND ZERO-PHASE JD2451497.796000 SAME ORIENT AS 01 BETWEEN 16-Apr-2000 AND 27-May-2000 MAX DUR 100% POS TARG 0.000, 1.000 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD209458 WAVE ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6094 ------------------------------------------------------------------------------------------------------------------------------------