9983( 4) - 08/07/03 13:04 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9983 Version: 4 Check-in Date: 07-Aug-2003 13:04:06 1.Proposal Title: Hubble Heritage Observations of Ring Galaxy AM0644-741 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO/DD 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Keith Noll Space Telescope Science Institute CoI: Ian Jordan Computer Sciences Corp/STScI N CoI: James Higdon Cornell University N CoI: Howard Bond Space Telescope Science Institute N CoI: Carol Christian Space Telescope Science Institute N CoI: Lisa Frattare Space Telescope Science Institute N CoI: Forrest Hamilton Computer Sciences Corp/STScI Y CoI: Zolt Levay Space Telescope Science Institute N CoI: Tricia Royle Space Telescope Science Institute N 9983( 4) - 08/07/03 13:04 - [ 2] ------------------------------------------------------------------------------------ 5. Abstract Ring galaxies are an aesthetically captivating galactic/inter-galactic phenomenon which HST is exceptionally qualified to observe. AM0644-741, the Lindsay-Shapley ring galaxy, will be observed as part of the Hubble Heritage Project. The Cartwheel galaxy (AM0035-335) is similar in shape and morphology to AM0644-741, but the Cartwheel's ring has a smaller angular scale on the sky and is about 50% further away. With a larger apparent size not completely capturable in a single WFPC2 pointing, about 30% better absolute spatial resolution should be achievable with AM0644-741 compared with the Cartwheel. AM0644-741 and two companion galaxies (including a candidate impactor) fits within a single rough ACS pointing. The ring itself represents a relatively brief but important transient evolutionary stage in only a small fraction of galaxies in the universe. It is believed that rings such as found in AM0035-335 and AM0644-741 are likely produced after a collision between two or more galaxies with a relatively narrow range of encounter velocities, relative masses, and impact parameters. If the encounter is outside of this parameter space, other unique tidal features can be produced, such as tails and mergers. The Cartwheel and AM0644-741 are at roughly similar evolutionary stages. But rings are not uniquely formed from collisions of the type producing the Cartwheel. For example, Hoag's Object represents an apparent ring galaxy likely formed by a different mechanism: complete tidal disruption of a closely orbiting small galaxy around a giant elliptical. In the case of the Cartwheel and the southern ring galaxy AM0644-741, the rings are not entire disrupted galaxies, but probably material from within one of the galaxies which traces the result of a pass-through collision of an intruder galaxy. Indeed, both objects have nearby collision candidates. After passage of the intruder, the remanant velocity of the material is sufficient to continue expansion after closest approach shortly following pass-through, thereby forming a coherent, expanding ring structure. Local conditions in the ring are not the same as before the encounter, so gas and dust resident in the ring can collapse to produce starbursts. If AM0644-741 is so similar to the Cartwheel, then why image it with HST? The aim of the Heritage Project is to provide spectacular HST color images for public release, outreach, and education. AM0644-741 is nearly ideally sized to fit into the ACS/WFC. The Cycle 4 GO 5410 Cartwheel ( http://www.stsci.edu/cgi-bin/get-proposal-info?5410 ) program with WFPC2 was a 3- orbit observation set in only two colors: B (3200 seconds) & I (1800 seconds). Nevertheless, that composite picture has had enduring, wide appeal with the public, and has provided an aesthetic benchmark motivating this target selection. Five orbits in B, V, R, and I with ACS/WFC are to be used to produce a higher signal-to- noise product and provide richer color information at the high angular resolution inherent with HST. ------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 3] Observations Description ------------------------ A five-visit, single orbit per visit observing strategy has been selected to allow the most flexible scheduling opportunities. Within this, a 4-filter, wide-band imaging program includes approximately 2 orbits of integration time in F435W, and approximately 1-orbit in each of F814W, F625W, and F555W to allow the greatest chance of producing a vivid high color contrast composite. The ring galaxy, and its two closeby radial velocity elliptical companions fit compactly within the ACS/WFC field of view at the given orient. The adopted orient maximizes the occupancy of the two companions, although the chip gap passes nearly through the center of the ring. However, this orient allows bleeding from a bright 13.7 magnitude star to extend along a column avoiding the center and surrounding ring of the galaxy, passing through a relatively sparse area outside the main ring. A 4-point dither/POS TARG strategy is used to provide adequate sampling across the inter-chip gap and for transient and instrumental artifact rejection. An alternate orient 180-degrees away from this is possible given a review of the individual target pointings. An orient 90- degrees from that adopted is NOT optimal for production of a photogenic Heritage product due to the subsequent bleeding of the 13.7 magnitude star across the ring and through the galactic nucleus. Four of the single orbit visits are essentially identical in color and integration time, each containing three single exposures: 400 seconds of F814W, 550 seconds of F625W, and 1400 seconds of F435W. Each of these visits will have a different single pointing in the 4-point dither strategy. The fifth visit contains a single orbit of V-band (F555W), with a single exposure at each of the 4 pointings of the previous four visits, allowing a 4-color strategy to optimally fit into a 5-orbit observation set for this target. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AM0644-741 GALAXY, RING RA=6H 43M 16.59S +/- 0.1", DEC=- J2000 B = 21.5+/-0.5 74D 14' 22.23" +/- 0.5", PLATE- ID=0095 Coordinate Source: GSC_SURVEY_PLATE Comments: VTT Generated target from DSS image. 2 AM0644-741- GALAXY, RING RA=6H 43M 11.54S +/- 0.1", DEC=- J2000 B = 21.5+/-0.5 D285 74D 14' 0.7" +/- 0.5", PLATE- ID=0095 Coordinate Source: GSC_SURVEY_PLATE Comments: VTT Generated target from DSS image. 3 AM0644-741- GALAXY, RING RA=6H 43M 19.48S +/- 0.1", DEC=- J2000 B = 21.5+/-0.5 D15 74D 14' 3.19" +/- 0.5", PLATE- ID=0095 Coordinate Source: GSC_SURVEY_PLATE Comments: VTT Generated target from DSS image. 4 AM0644-741- GALAXY, RING RA=6H 43M 21.26S +/- 0.1", DEC=- J2000 B = 21.5+/-0.5 D105 74D 14' 18.29" +/- 0.5", PLATE- ID=0095 Coordinate Source: GSC_SURVEY_PLATE Comments: VTT Generated target from DSS image. 9983( 4) - 08/07/03 13:04 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE ACS-WFC-DITHER-LINE Pattern_Purpose OTHER DITHER Number_Of_Points 2 2 Point_Spacing 3.011 0.146 Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 85.28 47.17 Center_Pattern NO NO ------------------------------------------------------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 6] Visit: 01 Visit Priority: Visit Requirements: ORIENT 10D TO 20D SCHED 60% On Hold Comments: Additional Comments: Alternate places - ORIENT 190-200 with target #1 ORIENT 280-290 with target #2 ORIENT 10-20 with target #3 ORIENT 100-110 with target #4 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 AM0644-741- ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=1 1 400 S D15 C ------------------------------------------------------------------------------------------------------------------------------------ 20 AM0644-741- ACS/WF ACCUM WFC F625W GAIN=1,CR-SPLIT=NO 1 550 S D15 C ------------------------------------------------------------------------------------------------------------------------------------ 30 AM0644-741- ACS/WF ACCUM WFC F435W GAIN=1,CR-SPLIT=NO 1 1400 S D15 C ------------------------------------------------------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 7] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 SCHED 60% 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 AM0644-741- ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=1 1 400 S POS TARG 0.099, 0.107 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 20 AM0644-741- ACS/WF ACCUM WFC F625W GAIN=1,CR-SPLIT=NO 1 550 S POS TARG 0.099, 0.107 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 30 AM0644-741- ACS/WF ACCUM WFC F435W GAIN=1,CR-SPLIT=NO 1 1400 S POS TARG 0.099, 0.107 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 8] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENT AS 01 SCHED 60% 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 AM0644-741- ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=1 1 400 S POS TARG 0.248, 3.001 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 20 AM0644-741- ACS/WF ACCUM WFC F625W GAIN=1,CR-SPLIT=NO 1 550 S POS TARG 0.248, 3.001 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 30 AM0644-741- ACS/WF ACCUM WFC F435W GAIN=1,CR-SPLIT=NO 1 1400 S POS TARG 0.248, 3.001 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 9] Visit: 04 Visit Priority: Visit Requirements: SAME ORIENT AS 01 SCHED 60% 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 AM0644-741- ACS/WF ACCUM WFC F814W CR-SPLIT=NO,GAIN=1 1 400 S POS TARG 0.347, 3.108 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 20 AM0644-741- ACS/WF ACCUM WFC F625W GAIN=1,CR-SPLIT=NO 1 550 S POS TARG 0.347, 3.108 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 30 AM0644-741- ACS/WF ACCUM WFC F435W GAIN=1,CR-SPLIT=NO 1 1400 S POS TARG 0.347, 3.108 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 10] Visit: 05 Visit Priority: Visit Requirements: SAME ORIENT AS 01 SCHED 60% 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 AM0644-741- ACS/WF ACCUM WFC F555W CR-SPLIT=NO,GAIN=1 1 550 S PATTERN 1 10 D15 C ------------------------------------------------------------------------------------------------------------------------------------ 9983( 4) - 08/07/03 13:04 - [ 11] Summary Form for Proposal 9983 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO GAIN=1 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 10D TO 20D SCHED 60% SAME ORIENT AS 01 SCHED 60% POS TARG 0.099, 0.107 POS TARG 0.248, 3.001 POS TARG 0.347, 3.108 PATTERN 1 10 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F625W F435W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AM0644-741-D15 ------------------------------------------------------------------------------------------------------------------------------------