Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5434 Report Date: 18-Jul-95:17:22 Version: ********** Check-in Date: ********** 1.Proposal Title: THE STELLAR POPULATION AND STAR FORMING HISTORY OF IZW18 CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO Sub Category STELLAR POPULATIONS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Reginald J. Dufour RICE UNIVERSITY USA (713)527-4939 ------------------------------------------------------------------------------------ 7. Abstract We propose to obtain deep planetary and wide-field camera imagery of IZw18 --the dwarf galaxy which has the lowest known O/H abundance among the several hundred star -forming irregular and blue-compact galaxies studied spectro- scopically during the past decade. Deep imagery with the wide field camera through blue, visual, and red filters of the main body and several components will be used to characterize its stellar population and star formation history. Planetary camera imagery of its "star -bursting" main body will be used to resolve the dense OB associations in its core that are responsible for exciting the ionized gas and its blue-compact nature. Imagery with the wide field camera through Halpha and [OIII] 5007A filters will permit detailed study of the morphology and ionization of the ionized gas surrounding the main body of the galaxy. Since IZw18 is the most extreme example of super metal-poor star-forming dwarf irregular galaxies, and has been used to set the primordial helium abundance, study with the HST should have a significant impact on our understanding of such relatively rare systems which may be the closest thing to a nearby "Holy Grail" of galaxy formation and evolution ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 12.43 par: 0 10. Num targs pri: 3 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5434 PI: Reginald J. Dufour Proposal Title: THE STELLAR POPULATION AND STAR FORMING HISTORY OF IZW18 CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Reginald J. Dufour 3240 USA Donald R. Garnett 2710 USA Gregory A. Shields 3550 USA Evan D. Skillman 2710 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. Four groups of observations of IZw18 are proposed for Cycle 4: 1. WFPC2 (WFC) BVR imagery with the "wide-B" (F450W), "old-V" (F555W), and "wide-R" F702W filters. The "main body" of IZw18 will be centered in the WF3 CCD and the observations should be scheduled at a time when either WF2 or WF4 will have an orientation along PA=312deg relative to WF3. This will enable imagery of components A-C-D-E in two WFC CCDs along the PA=312deg (or 132deg) axis. The imagery will be CR-SPLIT deep (two 2400sec - "half orbit") exposures in order to reach V=28 stars with a S/N of about 10 (see next question). Since the distance of IZw18 is about 10Mpc, corresponding to a distance modulus of (m-M)=30.0, and is essentially unreddened, the brightest stars (Mv=-7 OB stars) are expected to be near V=23 apparent magnitude. 2. WFPC2 (WFC) Halpha and [OIII]5007 imagery with the F658N and F502N filters. HI and Fabry-Perot observations indicate that the gas in and around IZw18 is redshifted by about 750 (+/-70) km/sec. For +750 km/sec the 6562.8A Halpha line will be at 6579.2 (thus a good match for the F658N filter) and the 5006.8A [OIII] line will be at 5019.3A (still in the high transmission part of the F502N filter). This imagery will be used to obtain high resolution maps of the ionized gas in the main body of IZw18 (which extends out over 25 arcsec from the main body in the NE and SW directions). An [OIII]/Halpha ratio map will be constructed which will enable charaterization of the ionization level and sources of this extended emission. As for (1) above, we plan to take two "CR-SPLIT" 2400sec exposures through each filter, hopefully at a time when the corners of the PC are along PA=312 so as to have the longest part of the PC follow the elongations of the galaxy components. 3. WFPC2 (PC) BVR imagery of the main body of IZw18 through the F439W, F555W, and F675W filters. The region to be centered in PC1 is the brightest core of the two main body associations (which are separated by 5.5"). The objective here is to reap the maximum spatial resolution of HST at some sacrifice of limiting magnitude in order to separate OB stars in IZw18 as much as possible. (CoI Garnett notes that a proprietory Cycle 2 WFC F220W image shows very dense clustering of OB stars in the NW component and we need maximum resolution to resolve these stars). We further choose F439W instead of F450W to supress the surrounding nebulosity as much as possible (a similar argument holds for F555W compared to F606W). We use F675W for R because it is the best calibrated. 4. FOS/RD spectra with G190H and G570H gratings with the 1.0-PAIR-B aperture in order to obtain and accurate measurement of the CIII]1909, SiIII]1883,92, OIII]1660,66 UV lines and optical tie-in with Halpha for exactly the same aperture. This, in conjunction with our optical spectra, will enable very accurate ratios of C:N:O:Si:H to be determined in this most metal-poor of star forming galaxies known. Our exposures are based on a previous G190H spectrum of IZw18 (3200sec) for which the aperture (1" circle) slightly missed the best postion. We expect to attain a S/N of about 6 for CIII]. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The proposed observations make fundamental use of the recovered high resolution image quality of the HST expected to be available for Cycle 4. In the section 2 discussion we noted the multi-component nature of IZw18 and the ever more interesting structures that become apparent with increasing sub-arcsecond resolution. For an assumed distance of 10Mpc for IZw18 (based on a mean Vr=+759 km/sec and Ho=75), 1 arcsecond corresponds to 48pc and (m-M)=30 suggests that the most luminous O stars will have V=23 (just at the limit of ground-based imagery). Therefore, using HST (limiting V~28 and resolution <0.1") we would expect to be able to study the brightest stars and surrounding emission nebulosities in the main body and possibly also the brightest stars and resolve the Halpha emission "knot" in component C to the NW. Our proposed WFC BVR imagery should detect stars as faint as about 28.5 (Mv=-1.5) corresponding to intermediate mass stars on the red-giant "tip" of evolution -thus enabling some evaluation of the existence of an intermediate or older age population in this chemically youngest of the star-forming galaxies known. The proposers have a demonstrated history of imagery and spectroscopy work on IZw18 in spectroscopy with the IUE (UV), McDonald, and MMT telescopes. We have published emission- line Halpha-[OIII]- [SII] imagery from Palomar, unpublished UBVRI imagery from McDonald, and unpublished Fabry-Perot imaging spectroscopy from CFHT available for enhanced use and interpretation of the HST imagery and spectroscopic observations proposed here. VLA HI maps of the galaxy have also been published for comparison with the optical-HST results. We propose using the F450W, F555W, and F702W filters with the WFC in order to reach the faintest stars possible for investment in spacecraft time. We performed calculations for V=23.0 (Mv=-7) and V=28.0 (Mv=-2) B0 stars in IZw18 using the instructions and data in the 1993 March WFPC2 Instrument Handbook. The signal-to-noise calculated for a single 2400sec "half- orbit" integration for the V=23 star was found to be (B,V,R) = (850,670,430) [Assuming a 23.3 mag/arcsec2 sky background and 7e-/pixel readout noise]. For a V=28.0 B0 star, the S/N expected on a 2400sec exposure is about (B,V,R) = (8,7,4) [But note that the S/N on the B (F450W) drastically drops for redder stars, such as G-K-M giants and supergiants]. A CR-SPLIT PAIR of 2400sec exposures would therefore result in quite accurate BVR color-magnitude diagrams down to V=28+ -- which is necessary to characterize the stellar population and ages in IZw18. Given the discovery of a very concentrated cluster of stars in the main body NW "core", result in quite accurate BVR color-magnitude diagrams down to V=28+ -- which is necessary to characterize the stellar population and ages in IZw18. Given the discovery of a very concentrated cluster of stars in the main body NW "core", we propose taking CR-SPLIT PAIRED 1200sec eposures with PC1 of WFPC2 of this region through the F439W ("B" - but avoiding the high transmission of the F450W filter at Hbeta-[OIII] around 4800-5100A from the bright core nebulosity), F555W (the narrower "V" F569W transmits the same as F555W at Halpha), and F702W "R". Compared to the WFC imagery above, we loose about a factor of 3-4 in photons detected, but gain a factor of 2 in spatial resolution--which may be essential to resolving the "core cluster" stars. Nonetheless, calculations suggest for a V=27.0 B0 star, the S/N on a 1200sec exposure will be about >5 in all passbands (the limiting factor will be background and crowding confusion around the core). Imagery of diffuse Halpha and [OIII]5007 (redshifted) emission poses a different set of problems. From Dufour & Hester (1990) and our higher- resolution CFHT imagery, the brightest knot in the main body of IZw18 has a measured surface brightness of 1.53E-14 ergs/cm-2/sec/arcsec2 and a 5007/6563 ratio of 0.6. From the WFPC2 manual, the F658N+OTA throughput at 6580.3A is 0.105 and for F502N+OTA at 5020.2A is 0.038. Correspondingly, the number of detected photons per sec per square arcsec is expected to be 24 for Halpha and 3.9 for [OIII]. These will be distributed (in an unknown fashion) in some 100 WFC2 pixels. Correspondingly, in a 2400sec exposure we would expect to have about 57,000 photoelectrons (or 8200 DN) detected at Halpha and about 9,400 (1340 DN) detected in [OIII] in a 10X10 pixel area. For the case of a very concentrated semi-stellar source, we correspondingly would have a high S/N of >100 for Halpha and >30 for [OIII]. Finally, we note that as part of the Cycle 2 program GO-3840, we obtained a 3200sec G190H/RD FOS spectrum of a position near the NW core of IZw18. This spectrum shows CIII]1909A and possibly SiIII]1883-92A lines but the offset position missed the brightest NW HII region core. Therefore, the S/N is lower than expected and we have received permission from STScI to "re-attempt" to take this spectrum with the 1" square aperture and an improved astrometric position. In addition, we propose to take a G570H spectrum for precise UV-optical tie-in for the location corresponding to the highest surface brightness HII region in IZw18. Page 4 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. We would like to schedule the WFC2 imagery to occur at a date such that the position angle of the centers of WF2 or WF4 is 312 (+/- 10) degrees -or 122 (+/- 10) degrees relative to the center of WFC3 (where the main body of the galaxy will be centered). Any of these four possible orientations will permit the more distant components (C-D-E) across the boundary of the WFC3 CCD into the field of WFC2 or WFC4 CCD. Each of these four orientations occur about 3 months apart and have about 20-day windows in time, so scheduling such would likely not be too tight. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None are anticipated to be needed. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Program GO-2416: "Imagery and Spectroscopy of Super Metal Poor Galaxies" PI: Dufour; CoIs common to this proposal: Skillman Program GO-3589: "High Resolution Parallel Imagery of Diffuse Objects in the Magellanic Clouds"; CoI common to this proposal: Garnett Program GO-3591: "Massive Stars in Starburst Galaxies"; CoI common to this proposal: Garnett Program GO-3840: "The Abundances and Time Evolution of Carbon, Nitrogen, and Oxygen in Star Forming Galaxies"; PI: Skillman; CoIs common to this proposal: Dufour, Garnett Program GO-4276: "The Abundance and Evolution of Carbon in the Spiral Galaxy NGC 2403: Cycle 3 Medium"; PI: Garnett; CoIs common to this proposal: Dufour, Skillman Program GO-4382: "HST Imagery and Spectroscopy of the Dusty SMC H II Region N88A: Cycle 3 High"; PI: Dufour; CoIs common to this proposal: Garnett, Skillman Program GO-4383: "UV Spectroscopy of Two Very C-Poor Halo Planetary Nebulae: Cycle 3 Medium"; CoI common to this proposal: Dufour Program GO-4385: "Ultra-Violet Spectroscopy of the Orion Nebula: Cycle 3 High"; Co-I common to this proposal: Dufour Program GO- 4497: "High Resolution Parallel Imagery of Diffuse Objects in the Magellanic Clouds"; CoI common to this proposal: Garnett GO-2416: An imaging and spectroscopic study of the nearby extreme low-mass dwarf irregular galaxy GR 8 (DDO 155), to study the stellar population and the morphology and composition of the ionized gas. WFC (F336W, F439W, F555W, F702W, F785LP, F502N, & F656N) and FOC/48 (F150W) images of the nearby low luminosity irregular galaxy GR8 were successfully obtained during Cycle 1. The wide-band WFC and FOC imagery came out very well, resolving numerous OB and red supergiants throughout GR8 for the first time (compared to previous ground- based studies). Broad-band photometry of the visible stars as faint as R=24.5 revealed a pattern of migrating star formation across this galaxy. The FOC imagery indicated that the two brightest stars "in GR8" are likely foreground objects. The FOS spectroscopy of one of the faint H II regions (obtained in 1993 February) displayed weak C III] emission and little else. Two poster papers on these results have been presented at AAS meetings and two at the 1993 March "Tex-Mex IV" meeting in Austin (for which summary papers will be published in Revista Mex. de Astron. y Astrof. in late 1993). Dufour is currently preparing a paper on the WFC photometry results for submission to the Astronomical Journal. "The Star Formation History of GR8 From HST Imagery," R.J. Wyatt and R.J. Dufour, Rev. Mex. Astr. Ap., 23, in press. "HST FOC/48 UV Imagery of GR8," B. Patterson, R.J. Wyatt, and R.J.Dufour, Rev. Mex. Astr. Ap., 23, in press. Page 5 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Dufour has in place at Rice a 19inch color Sparcstation 2GX with 64MBy of memory, 3GBy of hard disks, a 5GBy exabyte 8mm tape drive, and CD-rom reader. Installed on this machine and others in the department is a full IRAF-STDAS implimentation and other software such as DAOPHOT, SUPERMONGO, MATHEMATICA, etc. for astronomical data analysis. The university cost-shared in the purchase of much of this equipment. There also a color X-station etherneted to the Sparcstation for 2nd-party color graphics. Our department has another 7 UNIX and VMS based modern workstations and a color/B&W 35mm hardcopy camera system etherneted to these machines. The PI also has a 2nd year graduate student pursuing his M.S. thesis study on HST-related programs (Orion Nebula and SMC HII regions) as well as a postdoctoral fellow, Dr. Don Walter. The university cost shares in graduate student support. Skillman and Garnett have comparable color workstations and software in place at the University of Minnesota for the analysis of HST imagery and spectroscopy data and nebular model analysis. Shields has a variety of computational facilities at UT-Austin for his theoretical nebular modeling and analysis studies ------------------------------------------------------------------------------------ 11. Address Information Name: REGINALD J. DUFOUR Category: PI Institution: 3240 Address: SPACE PHYSICS AND ASTRONOMY RICE UNIVERSITY P. O. BOX 1892 City: HOUSTON State: TX Zip Code: 77251 Country: USA Telephone: 713 527 4944 Telex (or e-mail): RJD@RICE.EDU ------------------------------------------------------------------------------------ Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5434 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 IZW18- E,307 RA = 09H 34M 02.04S +/- J2000 V = +759 1 V=28.0, TYPE=B0V, E(B-V)=0.1 MAINBODY 0.05S, 2 SURF-LINE(6563) = 1.5 E-14 MARK116 DEC = +55D 14' 28.01" +/- 3 SURF-LINE(5007) = 9.0 E-15 0.1" Comments: THIS IS A DWARF IRREGULAR GALAXY BRIGHTEST STARS ARE AT V=23 ------------------------------------------------------------------------------------------------------------------------------------ 2 IZW18-NWHIIR H,503 RA-OFF = -4.25S +/- 0.03S, J2000 V = +759 EXT 1 SURF-LINE(6563) = 1.5 E-14 MARK116 DEC-OFF = -9.5" +/- 0.5", BKG 2 SURF-LINE(5007) = 9.0 E-15 FROM 3 3 SURF-LINE(1909) = 2.1 E-15 Comments: THIS IS THE BRIGHTEST HALPHA BLOB CIRCULAR WITH FWHM APPROX 0.5" ------------------------------------------------------------------------------------------------------------------------------------ 3 OFFSET-STAR A,138 RA = 09H 34M 06.29S +/- J2000 V = 0 1 V=15.4, B-V=+0.6, TYPE=G2V 0.03S, DEC = +55D 14' 37.5" +/- 0.5" Comments: THIS IS THE OFFSET STAR FOR THE IZW18- NWHIIR FOS SPECTRA PROPER MOTION UNKNOWN ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5434 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IZW18- WFPC2 IMAGE WF3-FIX F702W CR-SPLIT=NO 1 1800S 4 1 1 CYCLE 4 MAINBODY ORIENT 267D +/- 10D / 1.0-1.2 SEQ 1.0-1.2 NO GAP Comments: ORIENTATION FOR MB CENTERED IN WF3 GALAXY EXTENSIONS AT PA=312D IN WF2 THREE OTHER ORIENTATIONS POSSIBLE: - ORIENT=357D PUTS EXTENSIONS IN WF4 -ORIENT=87D WITH MAINBODY IN WF2 OK -ORIENT=177D WITH MAINBODY IN WF4 OK ------------------------------------------------------------------------------------------------------------------------------------ 1.1 IZW18- WFPC2 IMAGE WF3-FIX F450W CR-SPLIT=NO 2 2300S 8 1 1 CYCLE 4 MAINBODY Comments: ORIENTATION FOR MB CENTERED IN WF3 GALAXY EXTENSIONS AT PA=312D IN WF2 THREE OTHER ORIENTATIONS POSSIBLE: - ORIENT=357D PUTS EXTENSIONS IN WF4 -ORIENT=87D WITH MAINBODY IN WF2 OK -ORIENT=177D WITH MAINBODY IN WF4 OK ------------------------------------------------------------------------------------------------------------------------------------ 1.2 IZW18- WFPC2 IMAGE WF3-FIX F555W CR-SPLIT=NO 2 2300S 7 1 1 CYCLE 4 MAINBODY Comments: ORIENTATION FOR MB CENTERED IN WF3 GALAXY EXTENSIONS AT PA=312D IN WF2 THREE OTHER ORIENTATIONS POSSIBLE: - ORIENT=357D PUTS EXTENSIONS IN WF4 -ORIENT=87D WITH MAINBODY IN WF2 OK -ORIENT=177D WITH MAINBODY IN WF4 OK ------------------------------------------------------------------------------------------------------------------------------------ 1.3 IZW18- WFPC2 IMAGE WF3-FIX F702W CR-SPLIT=NO 2 1800S 4 1 1 CYCLE 4 MAINBODY ORIENT 267D +/- 10D / 1.3-1.5 SEQ 1.3-1.5 NO GAP Comments: ORIENTATION FOR MB CENTERED IN WF3 GALAXY EXTENSIONS AT PA=312D IN WF2 THREE OTHER ORIENTATIONS POSSIBLE: - ORIENT=357D PUTS EXTENSIONS IN WF4 -ORIENT=87D WITH MAINBODY IN WF2 OK -ORIENT=177D WITH MAINBODY IN WF4 OK ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5434 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1.4 IZW18- WFPC2 IMAGE WF3-FIX F502N CR-SPLIT=NO 2 2300S 1 3 1 CYCLE 4 MAINBODY Comments: ORIENTATION FOR MB CENTERED IN WF3 GALAXY EXTENSIONS AT PA=312D IN WF2 THREE OTHER ORIENTATIONS POSSIBLE: - ORIENT=357D PUTS EXTENSIONS IN WF4 -ORIENT=87D WITH MAINBODY IN WF2 OK -ORIENT=177D WITH MAINBODY IN WF4 OK ------------------------------------------------------------------------------------------------------------------------------------ 1.5 IZW18- WFPC2 IMAGE WF3-FIX F658N CR-SPLIT=NO 2 2300S 2 2 1 CYCLE 4 MAINBODY Comments: ORIENTATION FOR MB CENTERED IN WF3 GALAXY EXTENSIONS AT PA=312D IN WF2 THREE OTHER ORIENTATIONS POSSIBLE: - ORIENT=357D PUTS EXTENSIONS IN WF4 -ORIENT=87D WITH MAINBODY IN WF2 OK -ORIENT=177D WITH MAINBODY IN WF4 OK ------------------------------------------------------------------------------------------------------------------------------------ 2.1 IZW18- WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 2 600S 3 1 2 CYCLE 4 MAINBODY ORIENT 132D +/- 20D / 2.1-2.3 SEQ 2.1-2.3 NO GAP NON-INT Comments: ORIENTATION FOR MB CENTERED IN PC1 GALAXY EXTENSIONS AT PA=312D IN WF3 ------------------------------------------------------------------------------------------------------------------------------------ 2.2 IZW18- WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 2 1000S 3 1 2 CYCLE 4 MAINBODY NON-INT Comments: ORIENTATION FOR MB CENTERED IN PC1 GALAXY EXTENSIONS AT PA=312D IN WF3 ------------------------------------------------------------------------------------------------------------------------------------ 2.3 IZW18- WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 2 1000S 2 1 2 CYCLE 4 MAINBODY NON-INT Comments: ORIENTATION FOR MB CENTERED IN PC1 GALAXY EXTENSIONS AT PA=312D IN WF3 ------------------------------------------------------------------------------------------------------------------------------------ 3 OFFSET-STAR FOS/RD ACQ/ 4.3 MIRROR 1 18.8S 10 1 3 CYCLE 4 BINARY GROUP 3.0,3.1,3.2 NO GAP ONBOARD ACQ FOR 3.1-3.2 Comments: THIS IS THE V=15.4 OFFSET STAR FIELD IS CLEAR OF NEBULOSITY NO COMPARABLY BRIGHT STARS NEARBY ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5434 [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3.1 IZW18- FOS/RD ACCUM 1.0- G570H STEP- 1 300S 15 1 3 CYCLE 4 NWHIIR PAIR-B PATT=SINGLE GROUP 3.0,3.1,3.2 NO GAP Comments: THIS IS THE BRIGHTEST HII BLOB IN THE GALAXY, FWHM=0.5" SINGLE SPECTRUM TO BE TAKEN IN 1.0" SQUARE APERTURE "B" ------------------------------------------------------------------------------------------------------------------------------------ 3.2 IZW18- FOS/RD ACCUM 1.0- G190H STEP- 1 3600S 6 3 3 CYCLE 4 NWHIIR PAIR-B PATT=SINGLE GROUP 3.0,3.1,3.2 NO GAP Comments: THIS IS THE BRIGHTEST HII BLOB IN THE GALAXY, FWHM=0.5" SINGLE SPECTRUM TO BE TAKEN IN 1.0" SQUARE APERTURE "B" ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5434 [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO STEP-PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 12.43 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ORIENT 267D +/- 10D / 1.0-1.2; SEQ 1.0-1.2 NO GAP CYCLE 4 ORIENT 267D +/- 10D / 1.3-1.5; SEQ 1.3-1.5 NO GAP ORIENT 132D +/- 20D / 2.1-2.3; SEQ 2.1-2.3 NO GAP; NON-INT GROUP 3.0,3.1,3.2 NO GAP; ONBOARD ACQ FOR 3.1-3.2 GROUP 3.0,3.1,3.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F702W F450W F555W F502N F658N F439W F675W MIRROR G570H G190H ------------------------------------------------------------------------------------------------------------------------------------ Target Names IZW18-MAINBODY MARK116 IZW18-NWHIIR OFFSET-STAR ------------------------------------------------------------------------------------------------------------------------------------