6646( 6) - 02/29/96 15:41 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6646 Version: 6 Check-in Date: 29-Feb-1996 15:37:19 1.Proposal Title: WFPC2 Imaging of Dwarf Spirals ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle STELLAR POPULATIONS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: James Schombert NASA Headquarters CoI: Rachel Pildis Harvard-Smithsonian Center for N Astrophysics CoI: Jo Ann Eder Arecibo Observatory N CoI: Augustus Oemler Observatories of the Carnegie Inst of N Washingtion ------------------------------------------------------------------------------------ 6. Abstract This project proposes to obtain UV and blue WFPC2 images of a new class of galaxies: dwarf spirals. As with most low surface brightness (LSB) galaxies, dwarf spirals have the conflicting properties of very blue mean colors with little evidence of current or past star formation. We propose to resolve, or at least better define, this dilemma with WFPC2 imaging to investigate the nature and extent of the hot component of the stellar population in dwarf spirals. As a newly discovered class of galaxies, very little is known of their origin or evolution. Nothing is known of their UV properties. Their low contrast to the night sky makes them excellent candidates for space imaging. ------------------------------------------------------------------------------------ 6646( 6) - 02/29/96 15:41 - [ 2] Observations Description ------------------------ We propose three filter imaging of 5 targets. The filters we have selected are F255W, F336W (Johnson U) and F439W (Johnson B). To achieve our science goals we require the maximum S/N in the B filter for structure analysis (surface brightness profiles) and sufficient, but lesser S/N in filters F225W and F336W for areal (box) photometry. To achieve a depth of 23 B mag arcsec^-2 (the typical central surface brightness of our dwarfs) with a S/N of 2 per pixel will require approximately 2000 secs. The outer regions of these dwarfs will drop to 30 B mags arcsec^-2; however, there will be thousands of pixels to integrate over for surface photometric information. Although the throughput on the WFPC2 drops for the F225W and F336W regions, the night sky becomes even darker and we anticipate similar exposure times for those filters to achieve reasonable S/N for 2D color analysis. Our observing plan is to break the each orbit up into 4 exposures of 9 mins. Four exposures of 9 mins with 3 mins of overhead and 7 mins of guide star acquisition implies 52 mins of observation (last overhead is during Earth occultation). At the latitudes of these galaxies (all in the Arecibo declination range of 10 to 25), a HST orbit has 53 mins of useful observing. Each filter requires one orbit, thus, 5 objects through 3 filters requires 15 orbits. Our objects were selected for the highest elevation above the ecliptic plane; however, we have selected targets based primarily on their astrophysical interest, and only secondarily on their elevation angle. We request NO CR-SPLIT mode to reduce the overhead since the multiple frames per orbit will suffice for cosmic ray elimination. Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6646( 6) - 02/29/96 15:41 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 D564-15 GALAXY,LOW SURFACE RA=9H 11M 17.99S +/- 1.0", J2000. V = 3265 V = 16.5+/-0.5 BRIGHTNESS,SPIRAL, DEC=17D 10' 6.1" +/- 1.0" SURF(V) = 25.2+/-0.5 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000. 0.0 0.0 0.0 2 D721-5 GALAXY,LOW SURFACE RA=14H 2M 43.7S +/- 1.0", DEC=9D J2000. V = 5795 V = 17.3+/-.5 BRIGHTNESS,SPIRAL, 59' 28.8" +/- 1.0" SURF(V) = 24.8+/-.5 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000. 0.0 0.0 0.0 3 D774-1 GALAXY,LOW SURFACE RA=7H 49M 40.8S +/- 1.0", DEC=6D J2000. V = 4793 V = 14.79+/-0.5 BRIGHTNESS,SPIRAL, 36' 36.3" +/- 1.0" SURF(V) = 24.1+/-0.5 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000. 0.0 0.0 0.0 6646( 6) - 02/29/96 15:41 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 D774-1 WFPC2 IMAGE WF3 F255W CR- 1 600S SEQ 1 NON-INT; LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 D774-1 WFPC2 IMAGE WF3 F336W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 3 D774-1 WFPC2 IMAGE WF3 F439W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 6646( 6) - 02/29/96 15:41 - [ 5] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 D564-15 WFPC2 IMAGE WF3 F255W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 D564-15 WFPC2 IMAGE WF3 F336W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 3 D564-15 WFPC2 IMAGE WF3 F439W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 6646( 6) - 02/29/96 15:41 - [ 6] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 D721-5 WFPC2 IMAGE WF3 F255W CR- 1 600S SEQ 1 NON-INT; LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 D721-5 WFPC2 IMAGE WF3 F336W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 3 D721-5 WFPC2 IMAGE WF3 F439W CR- 1 600S LOW-SKY SPLIT=0.,DITHER - TYPE=LINE,DITHE R-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 6646( 6) - 02/29/96 15:41 - [ 7] Summary Form for Proposal 6646 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0. DITHER-TYPE=LINE DITHER-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1 NON-INT; LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F255W F336W F439W ------------------------------------------------------------------------------------------------------------------------------------ Target Names D774-1 D564-15 D721-5 ------------------------------------------------------------------------------------------------------------------------------------