! File: 5184C.PROP ! Database: PEPDB ! Date: 24-FEB-1994:00:03:57 coverpage: title_1: CURRENT HST IMAGING OF A NEARBY SPIRAL GALAXY sci_cat: GALAXIES & CLUSTERS sci_subcat: NEARBY GALAXIES proposal_for: GO/DD pi_title: DR. pi_fname: WILLIAM pi_lname: SPARKS pi_inst: STSCI pi_country: USA hours_pri: 3.42 num_pri: 1 wf_pc: Y ! end of coverpage abstract: line_1: This proposal is to obtain images of a spiral galaxy in the Virgo line_2: cluster with the HST in its aberrated state. The target is a high line_3: priority Early Release Observation (ERO) target for SMOV observation, line_4: but lacks images taken with WF/PC-1. We can use these data to provide line_5: information on the brightness of the nuclear regions to assist in line_6: planning of the post-refurbishemnt observation, and also to provide a line_7: baseline for comparative presentation, showing both "before" and line_8: "after" images. The proposed observations closely resemble the line_9: anticipated ERO observations, comprising short exposures to image the line_10: nuclear regions and lengthier ones to demonstrate the ability to line_11: observe Cepheid variables at the Virgo cluster. ! ! end of abstract general_form_proposers: lname: SPARKS fname: WILLIAM title: DR. inst: STSCI country: USA esa: N ! lname: GALLAGHER fname: JAY title: DR. mi: S. inst: 3884 country: USA esa: N ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: This proposal is to obtain images of a spiral galaxy in the Virgo cluster with line_2: the HST in its aberrated state. The target is a high priority Early Release line_3: Observation (ERO) target for SMOV observation, but lacks images taken with line_4: WF/PC-1. We can use these data to provide information on the brightness of the line_5: nuclear regions to assist in planning of the post-refurbishemnt observation, line_6: and also to provide a baseline for comparative presentation, showing both line_7: "before" and "after" images. The proposed observations closely resemble the line_8: anticipated ERO observations, comprising short exposures to image the nuclear line_9: regions and lengthier ones to demonstrate the ability to observe Cepheid line_10: variables at the Virgo cluster. line_12: The limited flexibility during SMOV does not allow us the freedom to select line_13: which target is the first observed. It is crucial therefore that images be line_14: available for ALL targets with HST in the present, aberrated state. M100 is the line_15: only high priority ERO target that falls into such a category. The reason it line_16: has not been observed, primarily, is that the Cepheid distance scale problem line_17: has not yet been pushed out to Virgo. This is, of course, the very reason why line_18: we do now wish to observe this galaxy. line_20: A major goal of the Hubble Telescope is to resolve individual stars in galaxies line_21: in the Virgo Cluster. This information is critical to an improved line_22: extragalactic distance scale, and thus determination of the Hubble constant, as line_23: well as to an enhanced understanding of the structures and evolution of ! question: 2 section: 2 line_1: galaxies. We propose to demonstrate the recovery of this capability with WFPC2 line_2: by imaging M100 (NGC 4321), a grand design, two-arm spiral in the Virgo line_3: cluster. M100 not only will offer us a spectacular close-up of the resolved line_4: stellar components across the arms of a large spiral galaxy of the type used to line_5: find distances via the Tully-Fisher method, but also affords us a chance to line_6: probe the poorly understood environment around an actively star-forming line_7: galactic nucleus. line_9: Images of M100 should be obtained in three filters with moderately long line_10: exposures to allow us to construct a color image of the galaxy. In line_11: the post-refurbishment observations, the pointing line_12: can be chosen such that the PC chip observes the nuclear region, while the WF line_13: chips fall along inner and outer spiral arms. We can then demonstrate how the line_14: configuration of WFPC2 can be effectively applied to extragalactic targets. line_15: Results of a three filter exposure can be expected to include measurements of line_16: luminous stellar populations across spiral arms where individual stars will be line_17: resolved, observations of interstellar matter as dark clouds, especially in line_18: the inner regions of the galaxy, a census of star clusters, and a first look at line_19: the distributions of stars and gas (via dust lanes) near the nucleus. ! question: 2 section: 3 line_1: Excellent ground-based data are available for this galaxy; e.g. see the Sandage line_2: and Bedke Atlas for a continuum photograph. In addition Gallagher has narrow line_3: band images in the Halpha line taken under good seeing conditions, which show a line_4: the bright nucleus is surrounded by four arms which extend to a ring that line_5: divides the nuclear zone from the main spiral features. ! question: 3 section: 1 line_1: Short description of proposed observations line_3: We propose to obtain BV and R images, both very short images taken to explore line_4: the nuclear regions and assess the brightness levels there, and also lengthier line_5: exposures of order one orbit per filter which, post-refurbishment, should be line_6: adequate to detect Cepheids at the distance of Virgo. line_8: We use a POS TARG to place the nucleus of the galaxy closer to the pyramid and line_9: in the same position as it would be if we were observing with the PC on WFPC2. ! question: 4 section: 1 line_1: (a) Justify the need for the capabilities if HST. line_3: It is obvious that if aberrated HST images are to be compared to unaberrated line_4: ones, real data are infinitely preferable to simulated aberrated data, which is line_5: the only viable alternative. line_7: (b) Justify the amount of exposure time. line_10: We propose to obtain BV and R images, both very short images taken to explore line_11: the nuclear regions and assess the brightness levels there, and also lengthier line_12: exposures of order one orbit per filter which, post-refurbishment, should be line_13: adequate to detect Cepheids at the distance of Virgo. We calculate that half of line_14: the flux within a 10 arcsec aperture, as observed from the ground, is coming line_15: from a point source at the nucleus, it would saturate in 100s, 15s and 10s line_16: respectively for B,V and R. This is highly conservative - much or all of the line_17: flux is likely to be extended, however it is essential that we check with these line_18: observations. In addition to mimic Cepheid data, we require of order one orbit line_19: per filter. ! question: 5 section: 1 line_1: Special Scheduling line_3: It is imperative if this target is to be used during SMOV for the ERO program line_4: that the observations be obtained as soon as possible. ! question: 6 section: 1 line_1: Special calibrations line_3: None ! question: 7 section: 1 line_1: Data reduction and analysis line_3: The data will be extremely useful in allwing us to exercise the machinery line_4: we will use to process real ERO data. The techniques of using full true color line_5: and mosaicing to reproduce wfpc2-like images will be used. ! !end of general form text general_form_address: lname: Sparks fname: William title: Dr. category: PI inst: STScI addr_1: 3700 San Martin city: BALTIMORE state: MD zip: 21218 country: USA phone: 410-338-4827 telex: 410-338-1592 from_date: 21-MAR-88 to_date: 21-MAR-98 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC4321 name_2: M100 descr_1: E,301 pos_1: RA=12H 20M 23S +/- 0.5S, pos_2: DEC=+16D 6' 0" +/- 1.0" equinox: 1950 fluxnum_1: 1 fluxval_1: B=10.0 fluxnum_2: 2 fluxval_2: B-V=0.5 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 sequence_1: DEFINE sequence_2: SPIM targname: NGC4321 config: WFC opmode: IMAGE aperture: WF2-FIX sp_element: # num_exp: 2 time_per_exp: 1S fluxnum_1: 1 priority: 1 param_1: CR-SPLIT=NO, param_2: PRE-FLASH=NO req_1: CYCLE 3; req_2: POS TARG +22,-22 comment_1: INTENDED TO MOVE TARGET CLOSER comment_2: TO PYRAMID. ! linenum: 10.000 sequence_1: USE sequence_2: SPIM sp_element: F555W time_per_exp: X10 ! linenum: 11.000 sequence_1: USE sequence_2: SPIM sp_element: F439W time_per_exp: X60 ! linenum: 12.000 sequence_1: USE sequence_2: SPIM sp_element: F702W time_per_exp: X5 ! linenum: 20.000 sequence_1: USE sequence_2: SPIM sp_element: F555W time_per_exp: X900 ! linenum: 21.000 sequence_1: USE sequence_2: SPIM sp_element: F439W time_per_exp: X900 ! linenum: 22.000 sequence_1: USE sequence_2: SPIM sp_element: F702W time_per_exp: X600 ! linenum: 23.000 sequence_1: USE sequence_2: SPIM sp_element: F702W time_per_exp: X600 ! ! end of exposure logsheet ! No scan data records found