9789( 3) - 05/19/03 06:42 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9789 Version: 3 Check-in Date: 19-May-2003 06:40:03 1.Proposal Title: The Distance to the Pleiades ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Christopher Johns-Krull Rice University CoI: Dr. Jay Anderson Rice University N ------------------------------------------------------------------------------------ 5. Abstract Despite its fundamental importance to stellar astrophysics, the distance to the Pleiades open cluster remains in great dispute. Main-sequence fitting results in a distance of 132.3 +/- 1.9 pc, while the Hipparcos average parallax for Pleaides member stars gives a distance of 116.4 +/- 2.9 pc. If the Hipparcos distance is to be believed, our current understanding of stellar astrophysics is dramatically incomplete. On the other hand, it has been proposed that the Hipparcos parallax measurement to the Pleiades suffers systematic uncertainties which result in the discrepancy with the main-sequence fitting technique. The question will remain open until an independent distance measurement to the Pleiades cluster is performed. We will use ACS imaging to determine the parallax to the Pleiades to an accuracy of about 1.5%. This will resolve the current controversy over the distance to the cluster once and for all. ------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 2] Observations Description ------------------------ This program is intended to measure the parallax of the Pleiades using pointings at two epochs and supplementing the data with long time baseline ground data to constrain the proper motion. We will observe each field once at parallactic maximum and once at the followingparallactic minimum. Each observation (using the WFC) will last one orbit and will consist of 6 exposures. The exposure times are designed to maximize the signal-to-noise for the cluster stars without saturating them. At the same time, we choose the exposure times to allow the detector to read during the subsequent exposure. This latter requirement means that the exposure time must be 348 seconds or longer, so we choose 350 sec. Using the online ACS exposure time calculator, we verified that this exposure time will not saturate our cluster stars in the F475W filter. We are also taking an exposure through the F814W filter to get color information, and we used the ETC to determine exposure times of 10-15 seconds for our very red stars. The total number of exposures is determined by readout time and other exposure overheads. Using a CR split of 1 indicates that we can fit a total of 6 exposures into each orbit. We will also get good signal for 15 or so reference stars in each field. It is well known that the WFC camera suffers from considerable distortion. Anderson (2003, HST Calibration Workshop, in press) found that there are two major sources of distortion. First is the expected contribution from the OTA, which contains large linear and quadratic terms and some power in the 3rd and the 4th order terms. This OTA distortion is well measured and is the same for all filters. It has been observed to change slightly with breathing (by 0.05 pixel across the chip), but this variation is only present in the low-order terms so that we can easily remove this in our transformations. Another contribution to distortion appears to come from the filter itself. This is a small contribution, typically 0.05 pixel, but varies with a much higher spacial frequency (~200 pixels). This fine-scale distortion must be characterized for each filter by means of a look- up table sampled every ~64 pixels, but it does not appear to change over time, so that once corrected, it will only contribute an error of 0.01 pixel or so to the distortion error. We have these corrections for the two filters we propose to use, F475W and F814W (Anderson 2003). To randomize the fine-scale distortion error, we will take our four exposures of each field at three different pointings, with POS-TARGs of ~200 pixels in x and y. We will take five of the exposures in F475W (the best characterized in terms of distortion) and one in F814W, so that we will have high-accuracy color information for all the stars, member and non-member. Since this is a parallax proposal, we have fairly stringent time constraints. In the comment section of each visit, we give the optimal date for the visit. We also set timing requirements so that the cosine of the parallax angle is within 15% of its maximum possible value. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments 9789( 3) - 05/19/03 06:42 - [ 3] ------------------- ------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIEL STELLAR CLUSTER, OPEN RA=03H47M17.05S +/- 0.1", J2000 V = 18.45+/-0.1 D1A CLUSTER DEC=+24D14'50.67" +/- 0.1" B = 19.96 Coordinate Source: GSC_SURVEY_PLATE Comments: This field contains 5 cluster members. The V and B magnitude for the brightest cluster member is given above. 2 PLEIADESFIEL STELLAR CLUSTER, OPEN RA=03H47M15.39S +/- 0.1", J2000 V = 18.45+/-0.1 D1B CLUSTER DEC=+24D14'47.75" +/- 0.1" B = 19.96 Coordinate Source: GSC_SURVEY_PLATE Comments: This field contains 5 cluster members. The V and B magnitude for the brightest member is given above. 3 PLEIADESFIEL STELLAR CLUSTER, OPEN RA=03H48M12.23S +/- 0.1", J2000 V = 17.1+/-0.1 D2A CLUSTER DEC=+23D59'7.36" +/- 0.1" B = 19.92 Coordinate Source: GSC_SURVEY_PLATE Comments: This field contains 3 cluster members. The V and B magnitude for the brightest is given above. 4 PLEIADESFIEL STELLAR CLUSTER, OPEN RA=03H48M10.54S +/- 0.1", J2000 V = 17.1+/-0.1 D2B CLUSTER DEC=+23D59'3.98" +/- 0.1" B = 19.92 Coordinate Source: GSC_SURVEY_PLATE Comments: This field contains 3 cluster members. The V and B magnitude for the brightest is given above. 5 PLEIADESFIEL STELLAR CLUSTER, OPEN RA=03H48M37.62S +/- 0.1", J2000 V = 20.06+/-0.1 D3A CLUSTER DEC=+24D13'11.41" +/- 0.1" Coordinate Source: GSC_SURVEY_PLATE Comments: This field contains 2 Pleiades cluster members. The V magnitude for the brightest is given above. 6 PLEIADESFIEL STELLAR CLUSTER, OPEN RA=03H48M35.93S +/- 0.1", J2000 V = 20.06+/-0.1 D3B CLUSTER DEC=+24D13'8.55" +/- 0.1" Coordinate Source: GSC_SURVEY_PLATE Comments: This field contains 2 Pleiades cluster members. The V magnitude for the brightest is given above. 9789( 3) - 05/19/03 06:42 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% ORIENT 74.0D TO 76.0 D BETWEEN 14-JAN-2004:00:00:00 AND 19-MAR-2004:00:00:00 On Hold Comments: Additional Comments: The optimal date for this observation in Feb. 15, 2004. The visit should be made as close to that date as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIE ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=2, 1 15 S POS TARG -20,-1.6 LD1A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 2 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -20,-1.6 LD1A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -10,-0.8 LD1A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 0, 0 LD1A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 10, 0.8 LD1A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 20, 1.6 LD1A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% ORIENT 254.0D TO 256.0 D BETWEEN 15-JUL- 2003:00:00:00 AND 17-SEP-2003:00:00:00 On Hold Comments: Additional Comments: The optimal date for this observation is Aug. 16, 2003. The visit should be made as close to that date as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIE ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=2, 1 15 S POS TARG -20,-1.6 LD1B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 2 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -20,-1.6 LD1B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -10,-0.8 LD1B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 0, 0 LD1B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 10, 0.8 LD1B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 20, 1.6 LD1B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 7] Visit: 03 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% ORIENT 74.0D TO 76.0 D BETWEEN 14-JAN-2004:00:00:00 AND 19-MAR-2004:00:00:00 On Hold Comments: Additional Comments: The optimal date for this observation is Feb. 15, 2004. The visit should be made as close to that date as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIE ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=2, 1 10 S POS TARG -20,-1.6 LD2A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 2 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -20,-1.6 LD2A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -10,-0.8 LD2A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 0, 0 LD2A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 10, 0.8 LD2A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 20, 1.6 LD2A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 8] Visit: 04 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% ORIENT 254.0D TO 256.0 D BETWEEN 15-JUL- 2003:00:00:00 AND 17-SEP-2003:00:00:00 On Hold Comments: Additional Comments: The optimal date for this observation is Aug. 16, 2003. The visit should be made as close to that date as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIE ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=2, 1 10 S POS TARG -20,-1.6 LD2B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 2 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -20,-1.6 LD2B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -10,-0.8 LD2B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 0, 0 LD2B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 10, 0.8 LD2B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 20, 1.6 LD2B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 9] Visit: 05 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% ORIENT 74.0D TO 76.0 D BETWEEN 14-JAN-2004:00:00:00 AND 19-MAR-2004:00:00:00 On Hold Comments: Additional Comments: The optimal date for this observation is Feb. 15, 2004. The visit should be made as close to that date as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIE ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=2, 1 15 S POS TARG -20,-1.6 LD3A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 2 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -20,-1.6 LD3A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -10,-0.8 LD3A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 0, 0 LD3A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 10, 0.8 LD3A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 20, 1.6 LD3A C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 10] Visit: 06 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% ORIENT 254.0D TO 256.0 D BETWEEN 15-JUL- 2003:00:00:00 AND 17-SEP-2003:00:00:00 On Hold Comments: Additional Comments: The optimal date for this observation is Aug. 16, 2003. The visit should be made as close to that date as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLEIADESFIE ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=2, 1 15 S POS TARG -20,-1.6 LD3B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 2 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -20,-1.6 LD3B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG -10,-0.8 LD3B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 0, 0 LD3B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 10, 0.8 LD3B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6 PLEIADESFIE ACS/WF ACCUM WFC F475W CR-SPLIT=NO,GAIN=2, 1 350 S POS TARG 20, 1.6 LD3B C COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ 9789( 3) - 05/19/03 06:42 - [ 11] Summary Form for Proposal 9789 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO GAIN=2 COMPRESSION=DEF ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE SCHED 30% ORIENT 74.0D TO 76.0 D BETWEEN 14-JAN-2004 00 00 00 AND 19-MAR-2004 00 00 00 POS TARG -20,-1.6 POS TARG -10,-0.8 POS TARG 0, 0 POS TARG 10, 0.8 POS TARG 20, 1.6 PCS MODE FINE SCHED 30% ORIENT 254.0D TO 256.0 D BETWEEN 15-JUL-2003 00 00 00 AND 17-SEP-2003 00 00 00 PCS MODE FINE SCHED 30% ORIENT 74.0D TO 76.0 D BETWEEN 14-JAN-2004 00 00 00 AND 19-MAR-2004 00 00 00 PCS MODE FINE SCHED 30% ORIENT 254.0D TO 256.0 D BETWEEN 15-JUL-2003 00 00 00 AND 17-SEP-2003 00 00 00 PCS MODE FINE SCHED 30% ORIENT 74.0D TO 76.0 D BETWEEN 14-JAN-2004 00 00 00 AND 19-MAR-2004 00 00 00 PCS MODE FINE SCHED 30% ORIENT 254.0D TO 256.0 D BETWEEN 15-JUL-2003 00 00 00 AND 17-SEP-2003 00 00 00 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F475W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PLEIADESFIELD1A PLEIADESFIELD1B PLEIADESFIELD2A PLEIADESFIELD2B PLEIADESFIELD3A PLEIADESFIELD3B ------------------------------------------------------------------------------------------------------------------------------------