! File: 4369C.PROP ! Database: PEPDB ! Date: 20-FEB-1994:23:34:07 coverpage: title_1: YOUNG GALAXIES AND THE IONIZATION OF THE INTERGALACTIC MEDIUM sci_cat: GALAXIES & CLUSTERS sci_subcat: EVOLUTION/COSMOLOGY proposal_for: GO pi_fname: JAMES pi_mi: D. pi_lname: LOWENTHAL pi_inst: STSCI pi_country: USA hours_pri: 7.00 num_pri: 2 foc: Y funds_length: 12 off_fname: HERVEY off_mi: S. off_lname: STOCKMAN off_title: DEPUTY DIRECTOR off_inst: 3470 off_addr_1: 3700 SAN MARTIN DRIVE off_city: BALTIMORE off_state: MD off_zip: 21218 off_country: USA off_phone: 410-338-4700 ! end of coverpage abstract: line_1: We propose slitless spectroscopic observations with the FOC of two line_2: luminous star-forming galaxies at z~0.4 to determine the amplitude of line_3: their intrinsic Lyman breaks. The opacity to ionizing UV photons of line_4: even the closest starbursts, not to mention the Milky Way, remains line_5: highly uncertain and yet bears directly on such issues as the line_6: ionization source for the Lyman-alpha forest and other QSO line_7: absorption-line systems, the reionization of the early universe, the line_8: strength of the local UV background radiation, and the physical state line_9: of gas in galactic gaseous halos. By obtaining sensitive, line_10: low-resolution spectra covering the redshifted Lyman limit breaks of line_11: two actively star-forming, narrow-emission-line galaxies, we can line_12: directly measure or set limits on the escaping ionizing UV light. We line_13: will extrapolate the results to higher redshifts in an effort to line_14: interpret galaxies at early epochs and to test the hypothesis that line_15: primeval galaxies ionized the IGM at z>3. HST observations are line_16: required for this project due to the starbursts' extreme faintness and line_17: the need for sensitivity near 1300A. We also hope to resolve the line_18: galaxies spatially. ! ! end of abstract general_form_proposers: lname: HECKMAN fname: TIMOTHY mi: M inst: STSCI country: USA ! lname: LEITHERER fname: CLAUS inst: STSCI country: USA esa: Y ! lname: SMITH fname: LINDA inst: UNIVERSITY COLLEGE LONDON country: UNITED KINGDOM esa: Y ! lname: LOWENTHAL fname: JAMES title: PI mi: D. inst: STSCI country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We have selected two narrow-emission line galaxies satisfying the following line_2: criteria: line_3: (1) z>0.35 to shift the Lyman limit break well past geocoronal Ly-a; line_4: (2) u<20.5 and u-b<-0.5 to maximize the detectability of UV light; line_5: and (3) [O II] 3727A Rest Equivalent Width > 20A and FWHM < 300 line_6: km/s, indicative of copious star formation. line_8: We wish to obtain slitless spectra with the FOC operating in objective line_9: prism mode of each galaxy to measure the emergent flux below the Lyman line_10: limit. We require no more exposures than are necessitated by the line_11: spacecraft orbital parameters. line_13: We also require non-dispersed images of each galaxy to establish the line_14: wavelength zero-point of each spectrum, which must be obtained line_15: immediately following the images. For this purpose we have chosen the line_16: F342W filter, which will allow us to compare the morphologies of these line_17: z=0.4 starbursts with those at z=0 studied by Heckman with HST at the line_18: same rest wavelength, ~2500A. This filter also allows us to take line_19: advantage of the FOC's peak sensitivity. line_21: Galaxy z lambda(Lyman break) u u-b line_22: SGP1:10 0.426 1301A 20.14 -0.72 line_23: QNY1:32 0.445 1318 20.37 -0.69 ! question: 4 section: 1 line_1: HST is required for these observations because we need access to line_2: spectral regions just longward of geocoronal Lyman-alpha, but we also line_3: need high sensitivity for the detection of the low flux levels line_4: expected (F(lambda)~10e-16 erg/sec/cm^2/A at 1300A), so space-based line_5: observations are necessary but IUE is not a viable possibility. line_7: Furthermore, although our targets were originally discovered because they line_8: appeared unresolved in ground-based images, we expect that HST should line_9: be capable of resolving some basic morphological details. ! question: 7 section: 1 line_1: We will bin the spectra spatially and spectrally to enhance the line_2: signal-to-noise ratio. In the spatial direction, 40% of the light is line_3: contained within about 11 pixels, so we will sum pixels on line_4: approximately that scale, while in the spectral direction, we will bin line_5: essentially the entire spectrum between the short-wavelength line_6: sensitivity cutoff near 1200A and the (redshifted) Lyman limit near line_7: 1300A, comparing it to an equal spectral segment from above the Lyman line_8: limit. ! !end of general form text general_form_address: lname: LOWENTHAL fname: JAMES mi: D. category: PI inst: STScI addr_1: 3700 SAN MARTIN DRIVE city: BALTIMORE state: MD zip: 21218 country: USA phone: 410-516-5101 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: SGP1-10 descr_1: E,318 pos_1: RA=00H 55M 49.0S +/- 0.08S, pos_2: DEC=-28D 32' 08.6" +/-1" equinox: 1950.0 pos_epoch_bj: J pos_epoch_yr: 1990.00 rv_or_z: Z = 0.426 fluxnum_1: 1 fluxval_1: U=20.14 +/- 0.5 fluxnum_2: 2 fluxval_2: U-B=-0.72 +/- 0.5 ! targnum: 2 name_1: QNY1-32 descr_1: E,318 pos_1: RA=12H 34M 02.8S +/- 0.07S, pos_2: DEC=-00D 20' 53.4" +/- 1.0" equinox: 1950.0 pos_epoch_bj: J pos_epoch_yr: 1990.00 fluxnum_1: 1 fluxval_1: U=20.37 +/- 0.5 fluxnum_2: 2 fluxval_2: U-B=-0.69 +/-0.5 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 101.000 targname: SGP1-10 config: FOC/96 opmode: IMAGE aperture: 256X1024 sp_element: F342W num_exp: 1 time_per_exp: 900S priority: 1 req_1: CYCLE 3; req_2: POS TARG +0.0,-5.0; req_3: SEQ 101-102 NO GAP; comment_1: UNDISPERSED IMAGE FOR WAVELENGTH comment_2: CALIBRATION OF EXPOSURE 102. comment_3: IF NO GUIDE STAR PAIR IS AVAILABLE, comment_4: SINGLE GUIDE STAR IS ACCEPTABLE. ! linenum: 102.000 targname: SGP1-10 config: FOC/96 opmode: IMAGE aperture: 256X1024 sp_element: PRISM1 wavelength: 1140-5660 num_exp: 1 time_per_exp: 11700S priority: 1 req_1: CYCLE 3; req_2: POS TARG +0.0,-5.0; req_3: SEQ 101-102 NO GAP; comment_1: SPECTRUM OF GALAXY comment_2: IMAGED IN EXPOSURE 101 comment_3: IF NO GUIDE STAR PAIR IS AVAILABLE, comment_4: SINGLE GUIDE STAR IS ACCEPTABLE. ! linenum: 103.000 targname: QNY1-32 config: FOC/96 opmode: IMAGE aperture: 256X1024 sp_element: F342W num_exp: 1 time_per_exp: 900S priority: 1 req_1: CYCLE 3; req_2: POS TARG +0.0,-5.0; req_3: SEQ 103-104 NO GAP; comment_1: UNDISPERSED IMAGE FOR WAVELENGTH comment_2: CALIBRATION OF EXPOSURE 104. comment_3: IF NO GUIDE STAR PAIR IS AVAILABLE, comment_4: SINGLE GUIDE STAR IS ACCEPTABLE. ! linenum: 104.000 targname: QNY1-32 config: FOC/96 opmode: IMAGE aperture: 256X1024 sp_element: PRISM1 wavelength: 1140-5660 num_exp: 1 time_per_exp: 11700S priority: 1 req_1: CYCLE 3; req_2: POS TARG +0.0,-5.0; req_3: SEQ 103-104 NO GAP; comment_1: SPECTRUM OF GALAXY comment_2: IMAGED IN EXPOSURE 103 comment_3: IF NO GUIDE STAR PAIR IS AVAILABLE, comment_4: SINGLE GUIDE STAR IS ACCEPTABLE. ! ! end of exposure logsheet ! No scan data records found