5907( 0) - 07/18/95 18:34 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5907 Version: ********** Check-in Date: ********** 1.Proposal Title: Colour magnitude diagrams of two super- metal-rich globular clusters in M31 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Stellar Populations GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Pascale JABLONKA Observatoire de Meudon, DAEC CoI: Terry BRIDGES Institute of Astronomy, Cambridge N CoI: Andre MAEDER Observatoire de Geneve N CoI: Georges MEYLAN European Southern Observatory N CoI: Georges MEYNET Observatoire de Geneve N CoI: Ata SARAJEDINI Kitt Peak National Observatory N ------------------------------------------------------------------------------------ 6. Abstract We propose to observe one of the most metal-rich globular cluster ever found, G177, recently identified in M31. We wish to take deep images in V and I bands, taking advantage of the high spatial resolution and red sensitivity of the Planetary Camera of WFPC2/HST, in order to build their colour-magnitude diagrams. With respect to the outstanding properties of G177, we will address the questions of its metallicity, both in absolute scale, by confrontation with theoretical stellar evolutionary tracks, and in relative scale, by comparison with coeval observations of two other clusters, G1 and G170, used as standards. The data we propose to obtain would provide essential input for theories of stellar evolution, star formation history, and models of star cluster and galaxy formation. ------------------------------------------------------------------------------------ 5907( 0) - 07/18/95 18:34 - [ 2] Observations Description ------------------------ We plan to reach V~eq 26, with signal-to-noise ratio ~ 10 for unambiguous detection with good enough photometry in the CMDs. Our 3 clusters split into two classes: G170, and G177, whose positions relatively close to the center of M31 induce a rather high value of the sky surface brightness (~ 18.5 -- 19 Vmag arcsec^-2), and G1 which has a sky surface brightness ~ 22 Vmag arcsec^-2 since it is located far from the center of the galaxy. For G170, and G177, we plan to integrate about 1.5 hours in both F555W (V) and F814W (I) filters. This would produce about 4 orbits per cluster, with an optimized division in exposures which would provide a good orbit packing, while allowing of course for the GS acquisition and the readout overheads. For G1, we plan to integrate only 1/2 hour in both F555W (V) and F814W (I) filters. This would produce 2 orbits, with an optimized division in exposures which would provide a good orbit packing, while allowing for the GS acquisition and the readout overheads. Due to the multiplicity of exposures, cosmic-ray splits would not be necessary. The PC chip will be centered on the target clusters, for maximum spatial resolution there. The PC will be oriented to maximize the scientific output of the three surrounding WFC chips. Real Time Justification ----------------------- We need sub-pixel shifts in between frames. Because HST is undersampled, even by the PC, it becomes important to deal with this problem in our program. We have designed a program of exposures shifted by +/- 5.5 pixels. This will enable us to regain the sampling of the PC images required for high precision photometry. None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5907( 0) - 07/18/95 18:34 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC224-G1 EXT-CLUSTER RA=0H 32M 46.535S +/- 0.2S, J2000 V=13.70 B-V=0.86 V-I=0.93 SURF(V)=13.5 DEC=39D 34' 41.13" +/- 0.2", PLATE-ID=0738 2 NGC224-G177 EXT-CLUSTER RA=0H 42M 34.349S +/- 0.2S, J2000 V=16.05 B-V=1.27 DEC=41D 14' 02.04" +/- 0.2", PLATE-ID=0738 3 NGC224-G170 EXT-CLUSTER RA=0H 42M 32.426S +/- 0.2S, J2000 V=16.45 B-V=1.23 DEC=41D 10' 33.92" +/- 0.2", PLATE-ID=0738 Comments: the real coordinates of G170 are RA=0H 42M 32.093S +/- 0.2S, DEC=41D 10' 28.92" +/- 0.2" but we will shift it on the CCD by 5" to the north and 5" to the east in order to avoid a close bright star. 5907( 0) - 07/18/95 18:34 - [ 4] Visit: 01 Visit Requirements: PCS MODE F 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 NGC224-G1 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 2 400S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G1 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 2 500S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G1 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 2 500S POS TARG 0.25047,-0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G1 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 2 600S POS TARG 0.25047,-0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 5907( 0) - 07/18/95 18:34 - [ 5] Visit: 02 Visit Requirements: PCS MODE F 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 NGC224-G177 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 2 1100S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G177 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 2 1300S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G177 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 2 1300S POS TARG 0.25047,-0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G177 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 2 1300S POS TARG 0.25047,-0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC224-G177 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 1 1300S POS TARG 0.25047,0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC224-G177 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 1 1300S POS TARG 0.25047,0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 5907( 0) - 07/18/95 18:34 - [ 6] Visit: 03 Visit Requirements: PCS MODE F ORIENT 260D TO 280D On Hold Comments: Additional Comments: A bright star nearby to be avoided by given orientation: offset angle of 45D and target position angle of 225D+/-10D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC224-G170 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 2 1100S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G170 WFPC2 IMAGE PC1 F814W CR-SPLIT=NO 2 1300S POS TARG -0.25047,0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G170 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 2 1300S POS TARG 0.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G170 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO 2 1300S POS TARG -0.25047,0.25047 ------------------------------------------------------------------------------------------------------------------------------------ 5907( 0) - 07/18/95 18:34 - [ 7] Summary Form for Proposal 5907 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Stellar Populations ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE F POS TARG 0.0,0.0 POS TARG 0.25047,-0.25047 POS TARG 0.25047,0.25047 PCS MODE F ORIENT 260D TO 280D POS TARG -0.25047,0.25047 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC224-G1 NGC224-G177 NGC224-G170 ------------------------------------------------------------------------------------------------------------------------------------