9773( 5) - 07/10/03 12:52 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9773 Version: 5 Check-in Date: 10-Jul-2003 12:51:08 1.Proposal Title: Ram Pressure Stripping in the Virgo Spiral NGC 4522 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Jeffrey D. Kenney Yale University ------------------------------------------------------------------------------------ 5. Abstract We propose to image in BVI with HST ACS/WFC the highly inclined Virgo cluster spiral galaxy NGC 4522, which is perhaps the nearest and clearest case of a galaxy whose interstellar medium (ISM) is being actively stripped by the pressure of the intracluster medium (ICM). High resolution HST B-I mages of dust in the ISM will show important details of the interaction, such as what happens to giant molecular clouds in the interaction, how rapidly and cleanly disks are stripped, and whether star formation is triggered by ICM pressure. We will identify extraplanar star clusters which formed in the stripped gas, and from their ages and spatial distribution constrain the stripping history of NGC 4522. Only with the spatial resolution of HST can we map dust features down to the few pc scale of GMCs, and clearly identify stars clusters. In-depth study of this galaxy should provide new insight into the physical processes which occur in ICM-ISM interactions, and give us greater understanding of galaxy evolution in clusters of all types and at all redshifts. ------------------------------------------------------------------------------------ 9773( 5) - 07/10/03 12:52 - [ 2] Observations Description ------------------------ We plan to observe the Virgo spiral galaxy NGC 4522 with ACS/WFC in 3 bands: BVI. 3 orbits in B, 1 each in VI. The galaxy is nearly edge-on, and Virgo cluster is nearby, so the galaxy will extend a bit beyond the 202" ACS field of view. The center of the field is to be offset by 21" NW from the nucleus of the galaxy, so that we get good coverage of the NW extraplanar region, where HI and Halpha gas is detected, and where we wish to search for star clusters. The nucleus is intended to go in WF2, and most of the NW extraplanar region is to go in WF1. The input coordinates given are the offset position from the nucleus. The center of the field could be shifted by as much as 10" in any direction, if necessary. e.g to find guidestars. We would like an orientation which puts the NW region (about PA 335 on the sky) approximately (within 40 deg) along the Yaxis, so have chosen ORIENTAT = 297 to 17 degrees. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9773( 5) - 07/10/03 12:52 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4522 GALAXY, SPIRAL RA=12H33M38.64S +/- 1.0", J2000 V = SURF(V) = 21+/-0.5 DEC=+09D10'42.2" +/- 1.0" 2300.0 Coordinate Source: Other_Source: vla radio continuum Comments: globular clusters at peak of GCLF in this galaxy should have V=24 9773( 5) - 07/10/03 12:52 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 3.011 Coordinate_Frame POS-TARG Pattern_Orient 85.28 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 9773( 5) - 07/10/03 12:52 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 297.0D TO 17.0 D 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 NGC4522 ACS/WF ACCUM WFCENTE F814W CR-SPLIT=NO 1 756 S PATTERN 1 1 C R ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4522 ACS/WF ACCUM WFCENTE F606W CR-SPLIT=NO 1 786 S PATTERN 1 2 C R ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 1 none none none 1 tbd 01 1 2 none none none 1 tbd 01 1 3 none none none 1 tbd 01 2 1 none none none 2 tbd 01 2 2 none none none 2 tbd 01 2 3 none none none 2 tbd 9773( 5) - 07/10/03 12:52 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 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 NGC4522 ACS/WF ACCUM WFCENTE F435W CR-SPLIT=2 1 2452 S PATTERN 1 1 C R ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 02 1 1 none none 1 1 tbd 02 1 1 none none 2 1 tbd 02 1 2 none none 1 2 tbd 02 1 2 none none 2 2 tbd 02 1 3 none none 1 3 tbd 02 1 3 none none 2 3 tbd 9773( 5) - 07/10/03 12:52 - [ 7] Summary Form for Proposal 9773 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 297.0D TO 17.0 D PATTERN 1 1 PATTERN 1 2 SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F606W F435W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4522 ------------------------------------------------------------------------------------------------------------------------------------