! $Id: 5354,v 9.1 1994/07/27 17:00:17 pepsa Exp $ coverpage: title_1: IMAGING IN THE CRAB NEBULA sci_cat: INTERSTELLAR MEDIUM sci_subcat: SN & SNR proposal_for: GO pi_fname: KRIS pi_lname: DAVIDSON pi_inst: 2710 pi_country: USA pi_phone: 612-624-5711 hours_pri: 11.79 num_pri: 1 wf_pc: Y off_fname: RICK off_lname: DUNN off_title: ASSISTANT DIRECTOR off_inst: 2710 off_addr_1: OFFICE OF RESEARCH AND TECHNOLOGY TRANSFER off_addr_2: ADMINISTRATIVE SERVICES CENTER, UNIVERSITY OF MINNESOTA off_addr_3: 1919 UNIVERSITY AVE. off_city: ST. PAUL off_state: MN off_zip: 55455 off_country: USA off_phone: 612-624-8526 ! end of coverpage abstract: line_1: We propose to obtain two types of WFPC2 images of selected bright line_2: filaments in the Crab Nebula. High-spatial-resolution images of line_3: the brightest visual-wavelength emission lines will provide density line_4: profiles across gas condensations, to improve ionization models line_5: that are used to study chemical composition in this very important line_6: SNR. (The same images are also useful for some other problems.) line_7: Low-spatial-resolution images of UV emission lines will be used to line_8: discover whether any UV-bright spots exist in the Crab Nebula, line_9: possibly caused by additional heating mechanisms or other line_10: circumstances. The proposed images will be used in conjunction line_11: with Cycle 3 FOS results and continuing ground-based observations line_12: and ionization/abundance calculations. The observations proposed line_13: here are essentially similar to those in GO 2340, a Cycle 1 project line_14: that was never done, partly because of the HST's optical defect. ! ! end of abstract general_form_proposers: lname: DAVIDSON fname: KRIS inst: 2710 country: USA ! lname: BLAIR fname: WILLIAM inst: 2380 country: USA ! lname: FESEN fname: ROBERT inst: 1830 country: USA ! lname: HENRY fname: RICHARD inst: 3060 country: USA ! lname: MACALPINE fname: GORDON inst: 2660 country: USA ! lname: UOMOTO fname: ALAN inst: 2380 country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: All of these are WFPC2 exposures targeted in the Crab Nebula -- line_2: - line_3: (1) High spatial resolution: Filters F502N, F656N, F658N, and F673N line_4: to image [OIII], H-alpha, [NII], and [SII]. One image each, except line_5: that each image should be divided into 2 or preferably 3 separate line_6: exposures (see below). Integration time nearly 2 hours per filter. line_7: ...Supplementing these, an image should be made with filter F547M, line_8: to provide underlying continuum background to be removed from the line_9: emission-line images. An exposure time of about an hour is line_10: adequate for the F547M image (divided into 2 or 3 parts). line_11: - line_12: (2) Low spatial resolution UV exploratory image: The main UV image line_13: uses filter F170W to observe CIV 1548 + HeII 1640 + NIII 1750 + CIII line_14: 1908 emission. Total integration time about 2 hours, divided into 2 line_15: separate exposures. Underlying continuum is important here, line_16: necessitating a UV continuum image using either F300W or F336W line_17: (the former is listed in the OSF), with > 0.5-hour integration time. line_18: - line_19: All exposures are at nearly the same target location, EXCEPT that line_20: it is advantageous to shift position by a few pixels between sub- line_21: exposures, so instrumental defects don't always cover the same line_22: parts of the SNR. line_23: - ! question: 3 section: 2 line_1: ---- Note, concerning INSTRUMENT ORIENTATION: ---- line_2: In order to place important Crab Nebula filaments in all three WF line_3: CCD chips simultaneously, the +U3 axis should point approximately line_4: eastward. Because of the Crab's location near the ecliptic, line_5: the HST automatically has the desired orientation throughout the line_6: period January--April of any year. Thus, although the desired line_7: orientation is specified by an ORIENT special requirement in our line_8: observing plan, we expect this to be an "easy" requirement because line_9: it matches the nominal spacecraft orientation anyway, if the line_10: observations are done in the time period mentioned above. line_11: (The requested orientation is not absolutely essential for this line_12: project, but it is very desirable.) ! question: 4 section: 1 line_1: Theoretical models predict that a typical gas condensation in the line_2: Crab Nebula should have ionization structure with a scale size of line_3: the order of 0.2". Based on experience with many excellent line_4: photographs and CCD frames of the Crab, we know that ground-based line_5: images are inadequate for studying this structure. Because the line_6: surface brightnesses are low, deconvolution is difficult and line_7: speckle interferometry is impossible. The HST/WFPC2 appears to line_8: be the only available instrument that can provide adequate spatial line_9: resolution for this type of target. line_10: - line_11: In addition to high-spatial-resolution images at visual wavelengths, line_12: we also need exploratory UV images in order to discover whether line_13: UV-bright spots exist in the Crab nebula. UV images made with line_14: ASTRO/UIT had exposure times that were too short for this purpose line_15: by a factor of the order of 100. The combination of larger line_16: collecting area and longer possible exposure time makes HST/WFPC2 line_17: more suitable for this purpose. No other existing instrument is line_18: adequate. Even with HST/WFPC2, the effective spatial resolution line_19: in UV images of the Crab will be about 1", limited by S/N. line_20: (The FOC is unsuitable for this purpose because its post-COSTAR line_21: field size is too small.) ! question: 5 section: 1 line_1: There is no direct special scheduling requirement per se, line_2: but we think that the period January -- April is best line_3: for this program (in any year). The reason is based on line_4: spacecraft orientation, as follows: The Crab Nebula is line_5: somewhat larger than the WFPC2 field, and a particular instrument line_6: orientation range is desirable in order to image important line_7: nebular filaments in all three WFC chips simultaneously. line_8: The desired orientation is achieved if the +U3 (anti-solar) axis line_9: points approximately toward PA = 90 deg, i.e., if the Sun is due line_10: west of the target. Since the Crab Nebula is near the ecliptic, line_11: and passes behind the Sun in mid-June, the orientation requirement line_12: is satisfied during most of the January--April time period. line_13: As stated in question 3, this "special requirement" is highly line_14: desirable but not absolutely essential to the project. ! question: 6 section: 1 line_1: ---- None, so far as we know. ---- ! ! question: 8 section: 1 line_1: Two techniques that we hope to employ are worth mentioning line_2: (these both appear easy to do): line_3: (1) We wish to make sure that each of the three WFC chips line_5: includes an important Crab Nebula filament region, all line_6: at once. This requires a particular instrument orientation. line_7: We hope and expect that this "special requirement" is an line_8: easy one, for reasons outlined in questions 3 and 5. line_9: (2) Routinely, each 1-to-2 hour WFPC2 image will actually be two line_10: or three sub-exposures. We prefer that the instrument be moved line_11: slightly (by just a few pixels) between sub-exposures, so that line_12: fixed instrument defects do not fall in the same target line_13: locations in all of the sub-exposures. ! question: 9 section: 1 line_1: GO 2338, "Spectroscopy of ... Eta Carinae", KD was PI, results line_2: will be subm for publ late 1993. line_3: GO 2416, "Imagery and spectroscopy of super metal poor galaxies", line_4: KD was a CoI. line_5: GO 3815, "UV observations of Hubble-Sandage Variables...", line_6: KD is a CoI. Observations started but not completed yet. line_7: GTO 4831, "Imaging and Spectrophotometry of Seyfert Nuclei", line_8: AU is a CoI. line_9: GTO 4909, "Polarization Imaging of the Jet in Markarian 463", line_10: AU is PI. Publ in AJ 105, 1308 (1993). line_11: GO 4356, "Imaging and Spectroscopy in the Crab Nebula", line_12: same roster of investigators as this present proposal; line_13: obs not done yet. line_14: GO 4509, "A Spectroscopic Map of ... Eta Carinae", KD is PI; line_15: obs not done yet. line_16: ...Note that GO 4356 is Cycle 3 FOS spectroscopy of the Crab Nebula, line_17: part of the same overall project as this proposal. ! question: 10 section: 1 line_1: In most cases, the normal computer and data-analysis facilities, etc. line_2: GMM is obtaining relevant ground-based spectroscopy of the Crab the line_3: the McGraw-Hill Observatory (in which both Michigan and Dartmouth are line_4: participants), and we hope that additional ground-based imaging can be line_5: obtained there also, in support of the HST imaging proposed here. line_6: Students from some of our institutions will be involved in the data line_7: reduction and analysis, but we don't know the details yet because line_8: they depend on the availability of appropriate students. ! !end of general form text general_form_address: lname: DAVIDSON fname: KRIS category: PI inst: 2710 addr_1: ASTRONOMY DEPT. addr_2: UNIVERSITY OF MINNESOTA addr_3: 116 CHURCH ST. SE city: MINNEAPOLIS state: MN zip: 55455 country: USA phone: 612-624-5711 telex: KD@EA.SPA.UMN.EDU ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC1952-BRTFIL name_2: CRAB_NEBULA-BRTFIL descr_1: G,506,922,925,926,927 pos_1: RA = 5H 34M 29.2S +/- 0.1S, pos_2: DEC = +22D 00' 50.0" +/- 1.0" equinox: J2000 comment_1: BRT FILAMENT REGION IN CRAB NEB, comment_2: TO BE IMAGED IN WF3; WF2 AND WF4 comment_3: WILL IMAGE OTHER FILAMENTS. comment_4: EMISSION-LINE BRIGHTNESSES REFER comment_5: TO SMALL GAS CONDENSATIONS. comment_6: EMISSION LINES 6584 AND 6724 comment_7: ARE ABOUT AS BRIGHT AS 6563. comment_8: VALUE FOR 1640 HERE IS REALLY comment_9: THE SUM OF EMIS LINES 1549+1640+ comment_10: 1908, IN A VERY BRT BLOB. fluxnum_1: 1 fluxval_1: SURF(V) = 20.0 +/- 1.0 fluxnum_2: 2 fluxval_2: SURF-LINE(6563) = 1.0 +/- 0.7 E-15 fluxnum_3: 3 fluxval_3: W-LINE(6563) = 5.0 +/- 1.0 fluxnum_4: 4 fluxval_4: SURF-LINE(5007) = 2.0 +/- 1.3 E-15 fluxnum_5: 5 fluxval_5: W-LINE(5007) = 5.0 +/- 1.0 fluxnum_6: 6 fluxval_6: SURF-LINE(1640) = 1.0 +/- 0.5 E-15 fluxnum_7: 7 fluxval_7: W-LINE(1640) = 5.0 +/- 1.0 fluxnum_8: 8 fluxval_8: SURF-CONT(3000) = 2.5 +/- 1.5 E-17 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 11.000 sequence_1: DEFINE sequence_2: TRIPLE-IM targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: # num_exp: 1 time_per_exp: 2000S s_to_n: 10 fluxnum_1: 2 fluxnum_2: 3 fluxnum_3: 4 fluxnum_4: 5 priority: # param_1: CR-SPLIT=NO, param_2: CLOCKS=YES req_1: CYCLE 4 / 11-13; req_2: GROUP 11-13 NO GAP; req_3: ORIENT 87D +/- 8D / 11-13; req_4: POS TARG -0.6,-0.6 comment_1: ORIENT REQ ENSURES THAT IMPORTANT comment_2: FILAMENTS ARE IMAGED IN WF2, WF4 comment_3: AS WELL AS WF3. THIS SPEC REQ comment_4: IS NOT DIFFICULT, SEE QUESTIONS comment_5: 3 AND 5 IN THE GENERAL FORM. comment_6: SEE ALSO COMMENT FOR LINE 12. ! linenum: 12.000 sequence_1: DEFINE sequence_2: TRIPLE-IM targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: # num_exp: 1 time_per_exp: 2300S s_to_n: 10 fluxnum_1: 2 fluxnum_2: 3 fluxnum_3: 4 fluxnum_4: 5 priority: # param_1: CR-SPLIT=NO, param_2: CLOCKS=YES req_1: POS TARG -0.6, -0.6 comment_1: LINES 11,12,13 ARE ALIKE EXCEPT comment_2: FOR THEIR POS TARG VALUES. THIS comment_3: PROCEDURE IS A FANCIER FORM OF comment_4: CR-SPLIT. comment_5: S/N REFERS TO ONE PIXEL, ONE EXP. comment_6: SEE COMMENTS FOR LINE 11. ! linenum: 13.000 sequence_1: DEFINE sequence_2: TRIPLE-IM targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: # num_exp: 2 time_per_exp: 2300S s_to_n: 10 fluxnum_1: 2 fluxnum_2: 3 fluxnum_3: 4 fluxnum_4: 5 priority: # param_1: CR-SPLIT=NO, param_2: CLOCKS=YES req_1: POS TARG +0.6,+0.6 comment_1: SEE COMMENTS FOR LINES 11 AND 12. ! linenum: 101.000 sequence_1: USE sequence_2: TRIPLE-IM sp_element: F656N priority: 1 comment_1: H-ALPHA EMISSION LINE IMAGE ! linenum: 102.000 sequence_1: USE sequence_2: TRIPLE-IM sp_element: F658N priority: 3 comment_1: [NII] EMISSION LINE IMAGE ! linenum: 103.000 sequence_1: USE sequence_2: TRIPLE-IM sp_element: F502N priority: 3 comment_1: [OIII] EMISSION LINE IMAGE ! linenum: 104.000 sequence_1: USE sequence_2: TRIPLE-IM sp_element: F673N priority: 3 comment_1: [SII] EMISSION LINE IMAGE ! linenum: 111.000 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F547M num_exp: 2 time_per_exp: 800S s_to_n: 16 fluxnum_1: 1 priority: 4 param_1: CR-SPLIT=NO, param_2: CLOCKS=YES req_1: CYCLE 4 / 111-114; req_2: GROUP 111-114 NO GAP; req_3: ORIENT 87D +/- 8D / 111-114; req_4: POS TARG -0.6,-0.6 comment_1: SEE COMMENT FOR LINE 11. comment_2: LINES 111-114 ARE ALIKE comment_3: EXCEPT FOR POS TARG -- THEY comment_4: ARE LIKE A CR-SPLIT WITH A comment_5: SLIGHT INSTRUMENT MOVEMENT comment_6: BETWEEN SUB-EXPOSURES. ! linenum: 114.000 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F547M num_exp: 2 time_per_exp: 1000S s_to_n: 16 fluxnum_1: 1 priority: 4 param_1: CR-SPLIT=NO, param_2: CLOCKS=YES req_1: POS TARG +0.6,+0.6 comment_1: SEE COMMENTS FOR LINE 111. ! linenum: 201.000 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F170W num_exp: 1 time_per_exp: 2000S s_to_n: 5 fluxnum_1: 1 priority: 2 param_1: CR-SPLIT=NO param_2: SUM=2X2, param_3: CLOCKS=YES req_1: CYCLE 4 / 201-204; req_2: GROUP 201-204 NO GAP; req_3: ORIENT 87D +/- 8D / 201-204; req_4: POS TARG -0.6,-0.6 comment_1: UV EMIS LINES IMAGED IN LINES comment_2: 201-202. FOR UV IMAGING HERE, comment_3: S TO N REFERS TO 1 ARCSEC, NOT comment_4: 1 PIXEL. LINES 201 AND 202 ARE comment_5: ALIKE EXCEPT POS TARG, SEE comment_6: COMMENTS FOR LINES 111 AND 11. ! linenum: 201.500 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F170W num_exp: 1 time_per_exp: 2300S s_to_n: 5 fluxnum_1: 1 priority: 2 param_1: CR-SPLIT=NO param_2: SUM=2X2, param_3: CLOCKS=YES req_1: POS TARG -0.6,-0.6 comment_1: UV EMIS LINES IMAGED IN LINES comment_2: 201-202. FOR UV IMAGING HERE, comment_3: S TO N REFERS TO 1 ARCSEC, NOT comment_4: 1 PIXEL. LINES 201 AND 202 ARE comment_5: ALIKE EXCEPT POS TARG, SEE comment_6: COMMENTS FOR LINES 111 AND 11. ! linenum: 202.000 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F170W num_exp: 2 time_per_exp: 2300S s_to_n: 5 fluxnum_1: 1 priority: 2 param_1: CR-SPLIT=NO param_2: SUM=2X2, param_3: CLOCKS=YES req_1: POS TARG +0.6,+0.6 comment_1: SEE COMMENTS FOR LINE 201. ! linenum: 203.000 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F300W num_exp: 1 time_per_exp: 1000S s_to_n: 20 fluxnum_1: 1 priority: 2 param_1: CR-SPLIT=NO, param_2: SUM=2X2, param_3: CLOCKS=YES req_1: POS TARG -0.6,-0.6 comment_1: UV CONTINUUM IMAGED IN LINES comment_2: 203-204. SEE COMMENTS FOR comment_3: LINE 201. ! linenum: 204.000 targname: NGC1952-BRTFIL config: WFPC2 opmode: IMAGE aperture: WF3-FIX sp_element: F300W num_exp: 1 time_per_exp: 1000S s_to_n: 20 fluxnum_1: 1 priority: 2 param_1: CR-SPLIT=NO, param_2: SUM=2X2, param_3: CLOCKS=YES req_1: POS TARG +0.6,+0.6 comment_1: SEE COMMENTS FOR LINE 203. ! ! end of exposure logsheet ! No scan data records found