! $Id: 5386,v 4.1 1994/07/27 17:23:19 pepsa Exp $ coverpage: title_1: STELLAR POPULATIONS OF THE LEO II DWARF SPHEROIDAL GALAXY sci_cat: COOL STARS sci_subcat: STELLAR POPULATIONS proposal_for: GO pi_fname: KENNETH pi_mi: J pi_lname: MIGHELL pi_inst: COLUMBIA UNIVERSITY pi_country: USA pi_phone: 212-854-6899 hours_pri: 4.08 num_pri: 1 wf_pc: Y off_fname: BETH off_lname: ISRAEL off_title: ASSOC. DIRECTOR off_inst: 1770 off_addr_1: OFFICE OF PROJECTS AND GRANTS off_addr_2: 405 LOW MEMORIAL LIBRARY off_addr_3: COLUMBIA UNIVERSITY off_city: NEW YORK off_state: NY off_zip: 10027 off_country: USA off_phone: 212-854-6851 ! end of coverpage abstract: line_1: We propose to obtain deep V and I photometry of the Leo II dwarf spheroidal line_2: galaxy using the WFPC2 and the F555W and F791 filters. We will produce a deep line_3: HR diagram of this Local Group galaxy which will be analyzed to determine its line_4: age and star formation history. This galaxy has luminous carbon stars and an line_5: anomalously red horizontal branch which indicates the presence of at least some line_6: intermediate age stars, and suggests that Leo II is younger than the Draco and line_7: Ursa Minor dwarf spheroidals. ! ! end of abstract general_form_proposers: lname: MIGHELL fname: KENNETH mi: J inst: 1770 country: USA ! lname: RICH fname: R. MICHAEL inst: 1770 country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: Leo II has a distance modulus (m-M)=21.85 (Demers & Harris 1983). An line_2: intermediate-age turnoff would occur at V=25; an old trunoff at V=26. line_3: We seek (V-I) color errors less than 0.30 mag for a F0 star at V=27. line_4: A 4800 second exposure in F555W gives S/N=7.9 and a 4800 second exposure line_5: in F791W gives S/N=5.1. The combined color error is 0.28 mag. line_7: Filter: F555W has QT_integral = 0.0250 line_8: Star: V=27, F0 star has AB_V=0.030 (average of 500 and 600 nm) line_9: Stellar flux: I=(2.5E+11)*(QT_integral)*10**(-0.4(V+AB_V))=0.096 e/sec line_10: Sky: WF -> V=27.1 (Leo II is near the ecliptic), AB_V = 0.035 line_11: Sky flux: B=(2.5E+11)*(QT_integral)*10**(-0.4(V+AB_V))=0.087 e/sec line_12: Total Exposure: T=4800 sec line_13: S/N correction: C=0.261 (WF Center & Corner, avgerage of 400 and 800 nm) line_14: S/N=I*SQRT((T*C)/(B+I))= 7.9 in 4800 sec line_16: Filter: F791W has QT_integral = 0.0169 line_17: Star: V=27, F0 star has AB_V=0.080 (800 nm) line_18: Stellar flux: I=(2.5E+11)*(QT_integral)*10**(-0.4(V+AB_V))=0.062 e/sec line_19: Sky: WF -> V=27.1 (Leo II is near the ecliptic), AB_V = -0.55 line_20: Sky flux: B=(2.5E+11)*(QT_integral)*10**(-0.4(V+AB_V))=0.101 e/sec line_21: Total Exposure: T=4800 sec line_22: S/N correction: C=0.226 (WF Center & Corner, 800 nm) line_23: S/N=I*SQRT((T*C)/(B+I))= 5.1 in 4800 sec ! question: 3 section: 2 line_1: line_2: We will take 2x80 sec exposures with ATD-GAIN=15 and 4x1200 sec exposures with line_4: ATD-GAIN=7 for both filters (F555W and F791W). The short high-gain exposures line_5: increase the dynamic range of the long low-gain exposures. line_7: We would like all the exposures to be taken together as one group with only line_8: interruptions due to Earth occultations (GROUP 1-4 NO GAP). We would like line_9: all exposures to be made at the same position in the sky with the same line_10: telescope roll angle (SAME POS FOR 2-4 AS 1). Each 1200 second exposure will line_11: be split in half (CR-SPLIT=0.5) to minimize cosmic-ray contamination. ! question: 4 section: 1 line_1: See answer to question 4.a. on the HST Cycle 4 proposal general form. ! question: 5 section: 1 line_1: ! question: 6 section: 1 line_1: ! ! question: 8 section: 1 line_1: ! question: 9 section: 1 line_1: See answer to question 9. on the HST Cycle 4 proposal general form. ! question: 10 section: 1 line_1: See answer to question 10. on the HST Cycle 4 proposal general form. ! !end of general form text general_form_address: lname: MIGHELL fname: KENNETH mi: J category: PI inst: 1770 addr_1: DEPT. OF ASTRONOMY addr_2: COLUMBIA UNIVERSITY addr_3: 538 WEST 120TH STREET city: NEW YORK state: NY zip: 10027 country: USA phone: 212-854-6899 telex: MIGHELL@FIGARO.PHYS.COLUMBIA.EDU ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: LEO-II descr_1: E, 308 pos_1: RA = 11H 13M 32.00S +/- 0.10S, pos_2: DEC = +22D 09' 30" +/- 0.10" equinox: 2000.0 comment_1: POSITION CHOSEN TO AVOID BRIGHT comment_2: STAR NEAR THE CENTER OF THE GALAXY fluxnum_1: 1 fluxval_1: V=12.4 fluxnum_2: 2 fluxval_2: B-V=1.0 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: LEO-II config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F555W num_exp: 2 time_per_exp: 80S s_to_n: 7.9 s_to_n_time: 4800S fluxnum_1: 1 priority: 1 param_1: ATD-GAIN=15, CR-SPLIT=NO req_1: CYCLE 4; PCS MODE F; ! linenum: 2.000 targname: LEO-II config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F555W num_exp: 4 time_per_exp: 1200S s_to_n: 7.9 s_to_n_time: 1200S fluxnum_1: 1 priority: 1 param_1: ATD-GAIN=7, param_2: CR-SPLIT=0.5, param_3: CR-TOLERANCE=0.0 req_1: CYCLE 4; PCS MODE F; ! linenum: 3.000 targname: LEO-II config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F814W num_exp: 2 time_per_exp: 80S s_to_n: 5.1 s_to_n_time: 4800S fluxnum_1: 1 priority: 1 param_1: ATD-GAIN=15, param_2: CR-SPLIT=NO, req_1: CYCLE 4; PCS MODE F; ! linenum: 4.000 targname: LEO-II config: WFPC2 opmode: IMAGE aperture: PC1 sp_element: F814W num_exp: 4 time_per_exp: 1200S s_to_n: 5.1 s_to_n_time: 4800S fluxnum_1: 1 priority: 1 param_1: ATD-GAIN=7, param_2: CR-SPLIT=0.5, param_3: CR-TOLERANCE=0.0 req_1: CYCLE 4; PCS MODE F; req_2: GROUP 1-4 NO GAP; req_3: SAME POS FOR 2-4 AS 1; ! ! end of exposure logsheet ! No scan data records found