! File: 2691C.PROP ! Database: PEPDB ! Date: 17-FEB-1994:10:20:06 coverpage: title_1: PRECISION PARALLAXES OF CEPHEIDS AND RR LYRAES USING THE WF/PC sci_cat: STELLAR POPULATIONS sci_subcat: ASTROMETRY proposal_for: GO longterm: 1 pi_title: DR. pi_fname: DOUGLAS pi_mi: K. pi_lname: DUNCAN pi_inst: STSCI pi_country: USA pi_phone: 301-338-4935 keywords_1: STARS: CEPHEIDS, ASTROMETRY, PARALLAXES. hours_pri: 2.50 num_pri: 1 wf_pc: X time_crit: X funds_amount: 95662 funds_length: 24 off_fname: PETER off_lname: STOCKMAN off_title: ASS. DIRECTOR off_inst: SPACE TELESCOPE SCIENCE INSTITUTE. off_addr_1: 3700 SAN MARTIN DRIVE off_city: BALTIMORE, off_state: MD off_zip: 21218 off_country: USA off_phone: 301-338-4700 off_telex: 684-9101 ! end of coverpage abstract: line_1: A new technique using the WF/PC should allow astrometric positions to be line_2: determined with an accuracy of 0.0002 arcsec 0.2 m.a.s. from two PC frames. line_3: We propose an initial test of the technique. line_14: Our new technique involves trailing HST during exposures to help alleviate the line_15: problem of undersampling inherent in the WF/PC. line_17: Once our technique of precision astrometry is proven, it line_20: should have numerous applications. ! ! end of abstract general_form_proposers: lname: GILLILAND fname: RONALD mi: L. inst: STSCI country: USA ! lname: VAN BUREN fname: DAVE inst: CANADIAN INST. FOR THEORETICAL ASTROPHYSICS country: CANADA ! lname: DUNCAN fname: DOUGLAS title: P.I. mi: K. inst: STSCI country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: Description of observations: line_2: This is a test of precision astrometry capability of WF/PC. line_3: In this case we observe a rich field of 14th magnitude stars line_4: in the globular cluster 47 Tuc. Goal is simply to measure line_5: the separation of all stars in the field of view in one line_6: dimension. In order to increase signal-to-noise, and obviate line_7: problems due to undersampling of the point-spread-function line_8: the images are trailed over about 75 pixels. The trailing line_9: is done at an angle of 35 degrees with respect to CCD coords line_10: to provide trails that are not degenerate in pixel sampling. line_11: In a science experiment to measure parallax, the trailing line_12: would be done perpendicular to the ecliptic, so that parallax line_13: offsets would be normal to the trails. Observations would line_14: be taken at epochs to maximize parallax displacements. line_15: For this test the trail direction in celestial coords is line_16: arbitrary. We require several independent observations to line_17: determine precision with which separation of trails can be line_18: measured. The TAC report requested that observations cover line_19: a solar UV flood of WF/PC as this might alter the shape of line_20: the chip -- this drives time critical aspect of these line_21: observations. ! question: 4 section: 0 line_1: Only HST will have the capability of pursuing this program. line_2: We should attain precisions a factor of 5 better than is now line_3: contemplated from the ground. While images obtained with line_4: ground-based observations can be centroided to the requisite line_5: sub-milli-arcsec level (with trailing and high S/N exposures) line_6: the atmosphere introduces offsets of apparent position which line_7: cannot be controlled to the accuracy we propose to measure. line_8: HST will provide relative image separations unaffected by the line_9: atmosphere. The large aperture of HST is required to reach line_10: high signal-to-noise on stars of mV = 17-18. Only at this line_11: level can an adequate number of background stars of similar line_12: magnitude be found. ! question: 5 section: 0 line_1: Spacecraft time required is primarily driven by the overhead line_2: components for this test experiment. We need guided line_3: exposures at two different S/N to allow identification of line_4: all stars in the field (required for subsequent analysis of line_5: trail separation) -- we request a total of three. line_6: The remaining exposures are all to generate trailed images, line_7: a sufficient number over two epochs have been requested line_8: to allow a determination of measurement precision. line_9: Independent trails at two different positions on the PC chips line_10: are used to determine the level of chip nonuniformity, and line_11: its potential impact on this project. line_12: In 47 Tuc the horizontal branch is at 14th mag, with the line_13: brightest stars being two magnitudes brighter. We have two line_14: constraints: 1) want to reach S/N a little better than 100 line_15: for the common 14th mag objects, 2) need to keep count rate line_16: in central pixels of brightest objects well under 80,000 cts line_17: to avoid any charge bleeding problems. At an exposure time line_18: of 0.4s (guided, or average per pixel in a trailed image) line_19: the S/N over full image will be about 135, with maximum cts line_20: per pixel of brightest stars at 43,000. This will produce line_21: ideal conditions for the test. At 0.4s per pixel exposure line_22: a trail over 75 pixels requires a 30s exposure. ! question: 6 section: 1 line_1: Observations must all be taken with stars at precisely line_2: the same positions (includes roll angle) on the chip. line_3: The TAC request that we sample two epochs before and after line_4: a solar UV flood coupled with need for same roll angle, line_5: requires that first set of observations be taken within line_6: one week before a UV flood, and the second set taken within line_7: one week following the UV flood. line_8: We need good flat fielding, of order S/N=200, for all of our line_9: F555W exposures. We request that sufficient calibration line_10: exposures for cycle 1 be scheduled by the Institute such that line_11: this goal is met. ! question: 7 section: 0 line_1: We anticipate the 2-D CCD image data set will first be line_2: carefully reduced for overscan, bias, preflash, dark and line_3: flat-field. The primary reduction step for each frame will line_4: be to determine the relative separation of the program star line_5: trail with respect to each background star trail. The trails line_6: will in general be at an angle to the CCD rows and columns. line_7: Since the trail length is < 10% of CCD size, the trails line_8: generally will not overlap in the trail direction. Each line_9: trail (line segment) can be characterized by: x,y position, line_10: length and slope. The length and slope will be determined as line_11: a common global parameter for all trails in an exposure (if line_12: necessary length and slope could be generalized to a template line_13: curve common to each trail). The x,y position (in CCD row, line_14: columns) will be set for each trail by a full point-spread- line_15: function fit over the about 5x75 pixels involved. This can line_16: be thought of as performing a full simulation of each trail, line_17: using both analytic and empirical information on the PSF, line_18: with the x,y position adjusted via non-linear least-squares line_19: until an optimal match occurs with each trail. The two line_20: parameters x,y carry useful information only on the normal line_21: separation between line segments, not true 2-D position of line_22: stars on sky -- orthogonal trailing required for latter. ! !end of general form text general_form_address: lname: DUNCAN fname: DOUGLAS mi: K. title: DR. category: PI inst: SPACE TELESCOPE SCIENCE INSTITUTE addr_1: 3700 SAN MARTIN DRIVE city: BALTIMORE state: MD zip: 21218 country: USA ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC0104 name_2: 47TUC descr_1: STAR CLUSTER; GLOBULAR CLUSTER pos_1: RA=00H 23M 58.00S +/-5.00S, pos_2: DEC=-72D 3' 14.4" +/-5.00" equinox: 1984 pos_epoch_bj: B pos_epoch_yr: 1984.00 comment_1: WE HAVE ONLY ONE FIELD. comment_2: LOCATION IN FIRST ACQUISITION comment_3: DOES NOT NEED TO BE BETTER comment_4: THAN +/- 5". IN SUBSEQUENT comment_5: ACQUISITION POSITIONING SHOULD comment_6: BE AS CLOSE TO ORIGINAL comment_7: AS POSSIBLE. fluxnum_1: 1 fluxval_1: V=14 +/- 3 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 0.4S s_to_n: 100 s_to_n_time: 0.4S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: GROUP 1-4 WITHIN 7D; req_2: ORIENT 25D +/- 0D FROM NOMINAL / 1-4.5; req_3: CYCLE 1 / 1-8; ! linenum: 2.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 4 time_per_exp: 78S s_to_n: 100 s_to_n_time: 30S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: SPATIAL SCAN SINGLE-EXP; req_2: SAME ORIENT FOR 2-4.2 AS 1; req_3: SAME POS FOR 2-8 AS 1 ! linenum: 3.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 3 time_per_exp: 78S s_to_n: 100 s_to_n_time: 30S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: SPATIAL SCAN SINGLE-EXP ! linenum: 4.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 80S s_to_n: 100 s_to_n_time: 260S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO, param_3: READ=NO req_1: SPATIAL SCAN;SEQ 4-4.2 NON-INT; req_2: SEQ 4-5 comment_1: SEQ 4-5 (AND AFTER 4 ON LINE 5) MAY comment_2: BE DELETED IF TRANS BREAKS ON THIS, comment_3: BUT CHANGE THE GROUP 1-4 TO SEQ 1-5 comment_4: ON LINE 1. ! linenum: 4.100 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 80S s_to_n: 100 s_to_n_time: 260S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO, param_3: READ=NO req_1: SPATIAL SCAN; req_2: POS TARG -5.404,9.190 comment_1: DELTA = 1.893,-2.703 ! linenum: 4.200 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 80S s_to_n: 100 s_to_n_time: 260S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO, param_3: READ=YES req_1: SPATIAL SCAN; req_2: POS TARG -8.107, 7.297 comment_1: DELTA = 4.596, -0.810 ! linenum: 4.300 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 80S s_to_n: 100 s_to_n_time: 260S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO, param_3: READ=NO req_1: SPATIAL SCAN; req_2: SEQ 4.3-4.5 NON-INT; ! linenum: 4.400 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 80S s_to_n: 100 s_to_n_time: 260S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO, param_3: READ=NO req_1: SPATIAL SCAN; req_2: POS TARG -5.404,9.190 comment_1: DELTA = 1.893,-2.703 ! linenum: 4.500 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 80S s_to_n: 100 s_to_n_time: 260S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO, param_3: READ=YES req_1: SPATIAL SCAN; req_2: POS TARG -8.107, 7.297 comment_1: DELTA = 4.596, -0.810 ! linenum: 5.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 2.0S s_to_n: 250 s_to_n_time: 2.0S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: AFTER 4.2 BY 45D; req_2: SAME ORIENT FOR 5-8 AS 1; comment_1: SEE COMMENTS ON LINE 4 ! linenum: 6.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 4 time_per_exp: 78S s_to_n: 100 s_to_n_time: 30S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: SPATIAL SCAN SINGLE-EXP; req_2: GROUP 6-7 WITHIN 7D; req_3: AFTER 5 ! linenum: 7.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 3 time_per_exp: 78S s_to_n: 100 s_to_n_time: 30S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: SPATIAL SCAN SINGLE-EXP; req_2: SEQ 7-8 ! linenum: 8.000 targname: NGC0104 config: PC opmode: IMAGE aperture: ALL sp_element: F555W wavelength: 5479 num_exp: 1 time_per_exp: 2.0S s_to_n: 250 s_to_n_time: 2.0S fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=15, param_2: CR-SPLIT=NO req_1: AFTER 7 ! ! end of exposure logsheet scan_data: line_list: 2, 6 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 3.3000 sides_angle: 0.0000 number_lines: 1 scan_rate: 0.0423 first_line_pa: 35.0000 scan_frame: S/C len_offset: 0.0000 wid_offset: 0.0000 ! line_list: 3, 7 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 3.3000 sides_angle: 0.0000 number_lines: 1 scan_rate: 0.0423 first_line_pa: 35.0000 scan_frame: S/C len_offset: 0.0000 wid_offset: 2.2000 ! line_list: 4, 4.3 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 3.3000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.0423 first_line_pa: 35.0000 scan_frame: S/C len_offset: 0.0000 wid_offset: 0.0000 ! line_list: 4.1,4.4 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 3.3000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.0423 first_line_pa: 125.0000 scan_frame: S/C len_offset: 0.0000 wid_offset: 0.0000 ! line_list: 4.2,4.5 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 3.3000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.0423 first_line_pa: 215.0000 scan_frame: S/C len_offset: 0.0000 wid_offset: 0.0000 ! ! end of scan data