6465( 8) - 12/23/96 10:15 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6465 Version: 8 Check-in Date: 23-Dec-1996 10:11:53 1.Proposal Title: The UV-upturn of super-metal-rich globular clusters ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle STELLAR POPULATIONS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Pascale JABLONKA Observatoire de Meudon, DAEC CoI: Eduardo BICA Universidade Federal do Rio Grande do Sul N CoI: Andre MAEDER Observatoire de Geneve N CoI: Georges MEYLAN European Southern Observatory N CoI: Georges MEYNET Observatoire de Geneve N CoI: Dante MINNITI Lawrence Livermore National Laboratory N ------------------------------------------------------------------------------------ 6. Abstract We propose to use the FOS to look for strong UV upturn in the spectral energy distributions of 6 super-metal-rich star clusters in M31. Our goal is to clarify whether the stellar population responsible for strong UV fluxes in galaxies can also be present in star clusters, i.e., if bluewards of 2500Angstrom, clusters can still be considered as galaxy templates. For this purpose, we have selected clusters with metal enrichment similar to those encountered in the galaxian nuclear regions, where strong UV fluxes are observed. ------------------------------------------------------------------------------------ Observations Description ------------------------ The domain of the G160L grating (LambdaLambda 1200-2500 Angstrom) is well suited to follow the UV rising branch. The 1.0-PAIR aperture corresponds to our needs. Indeed, the M31 clusters have core radii of ~0.1-0.2 arcsec Fusi Pecci et al., 1994, A&A, 284, 349. This implies that this 0.86'' aperture will collect most of the cluster flux, without suffering from field contamination. This PAIR aperture will also allow sky subtraction, although this is more a security check than a real need, since, following the work by O'Connell et al. 1992, ApJ, 395, L45, the UV radiation of field stars at the position of our clusters in M31 should be extremely faint. E.g. G177 is the closest cluster to the M31 nucleus, only 2.31 arcmin away Battistini et al., 1993, A&A, 272, 77; at this distance, the IUT photometry of the background indicates m(1520Angstrom)=25 mag and m(2500Angstrom)=22 mag (O'Connell, private communication). The lowest UV flux detected at ~1500Angstrom\\ for M31 star clusters is ~5 10^-16 erg/s/cm^2/Angstrom\\ Cowley & Burstein, 1988, AJ, 95, 1071; Bohlin et al., 1993, ApJ, 417, 127. Taking this value for G177 shows that the background will be at least 8 and 5 magnitudes below G177 levels, at 1520Angstrom\\ and 2500Angstrom, respectively . In our exposure time calculations, we refer to this minimum flux of 5 10^-16 erg/s/cm^2/Angstrom. We are looking for larger fluxes, consequently, these conservative calculations ensure data good enough to be analyzed in all cases. We shall use the ACCUM (SUB-STEP=4) and OVERSCAN=5 modes. We plan to reach S/N~10 per 2 pixels (half a diode, and ~3.43 Angstrom\\ per bin) at ~ 1500 Angstrom. The inverse sensitivity of G160L at 1500Angstrom\\ is 1.888 10^-14 erg/cm^2/count/Angstrom, and the point source post-COSTAR FOS 1.0-PAIR aperture throughput is 0.92*0.96=0.864. So we get 0.023 count/s/diode from the cluster, well above the dark of being 0.007 count/diode/s. S/N~10 can be reached in 5671 sec per diode, i.e. ~3 hours for our 2-pixels binning, equivalent to 3 orbits per cluster., We have checked, using Dr. M. Rosa (ST-ECF) code, that even for 47 Tuc type clusters (i.e., UV faint and already red in the visible), the redleack contamination will be smaller than 3\\ Our clusters should be in an even more favorable case. In any case, their optical spectra are available for any needed correction. Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6465( 8) - 12/23/96 10:15 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC224-G174 EXT-CLUSTER RA=0H 42M 33.48S +/- 0.2S, J2000 V = 16.30 DEC=41D 17' 32.60" +/- 0.2", B-V = 1.25 PLATE-ID=0738 Comments: Coordinates obtained from special STScI plates 2 NGC224-G177 EXT-CLUSTER RA=0H 42M 34.48S +/- 0.2S, J2000 V = 16.0 DEC=41D 14' 03.28" +/- 0.2", B-V = 1.31 PLATE-ID=0738 3 NGC224-G198 EXT-CLUSTER RA=0H 42M 59.62S +/- 0.2S, J2000 V = 16.0 DEC=41D 19' 19.14" +/- 0.2", B-V = 1.24 PLATE-ID=0738 Comments: Coordinates obtained from special STScI plates 4 NGC224-G170 EXT-CLUSTER RA=0H 42M 32.58S +/- 0.2S, J2000 V = 16.45 DEC=41D 10' 29.48" +/- 0.2", B-V = 1.37 PLATE-ID=0738 Comments: Coordinates obtained from special STScI plates 6465( 8) - 12/23/96 10:15 - [ 2] Visit: 01 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Coordinates need to be remeasured in the full gasp coordinate frame as the DSS for use in Phase II measurements is saturated. Present estimate comes from DSS-CDROM. 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-G174 FOS/BL ACQ/PEA 4.3 MIRROR SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3, 1 8.4 S ONBOARD ACQ FOR 2 K SEARCH-SIZE-X=1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G174 FOS/BL ACQ/PEA 1.0-PAI MIRROR SCAN-STEP-Y=0.61,SCAN-STEP-X=0.61 1 8.4 S ONBOARD ACQ FOR 3 K R ,SEARCH-SIZE-Y=2,SEARCH-SIZE-X=6 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G174 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-Y=0.17,SCAN-STEP-X=0.17 1 32 S ONBOARD ACQ FOR 4 K IR ,SEARCH-SIZE-Y=5,SEARCH-SIZE-X=5 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G174 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC224-G174 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC224-G174 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC224-G174 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6465( 8) - 12/23/96 10:15 - [ 3] Visit: 02 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Coordinates need to be remeasured in the full gasp coordinate frame as the DSS for use in Phase II measurements is saturated. Present estimate comes from DSS-CDROM. 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 FOS/BL ACQ/PEA 4.3 MIRROR SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3, 1 8.4 S ONBOARD ACQ FOR 2 K SEARCH-SIZE-X=1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G177 FOS/BL ACQ/PEA 1.0-PAI MIRROR SCAN-STEP-Y=0.61,SCAN-STEP-X=0.61 1 8.4 S ONBOARD ACQ FOR 3 K R ,SEARCH-SIZE-Y=2,SEARCH-SIZE-X=6 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G177 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-Y=0.17,SCAN-STEP-X=0.17 1 32 S ONBOARD ACQ FOR 4 K IR ,SEARCH-SIZE-Y=5,SEARCH-SIZE-X=5 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6465( 8) - 12/23/96 10:15 - [ 4] Visit: 03 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Coordinates need to be remeasured in the full gasp coordinate frame as the DSS for use in Phase II measurements is saturated. Present estimate comes from DSS-CDROM. 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 FOS/BL ACQ/PEA 4.3 MIRROR SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3, 1 8.4 S ONBOARD ACQ FOR 2 K SEARCH-SIZE-X=1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G177 FOS/BL ACQ/PEA 1.0-PAI MIRROR SCAN-STEP-Y=0.61,SCAN-STEP-X=0.61 1 8.4 S ONBOARD ACQ FOR 3 K R ,SEARCH-SIZE-Y=2,SEARCH-SIZE-X=6 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G177 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-Y=0.17,SCAN-STEP-X=0.17 1 32 S ONBOARD ACQ FOR 4 K IR ,SEARCH-SIZE-Y=5,SEARCH-SIZE-X=5 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC224-G177 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6465( 8) - 12/23/96 10:15 - [ 5] Visit: 04 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-G170 FOS/BL ACQ/PEA 4.3 MIRROR SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3, 1 8.4 S ONBOARD ACQ FOR 2 K SEARCH-SIZE-X=1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G170 FOS/BL ACQ/PEA 1.0-PAI MIRROR SCAN-STEP-Y=0.61,SCAN-STEP-X=0.61 1 8.4 S ONBOARD ACQ FOR 3 K R ,SEARCH-SIZE-Y=2,SEARCH-SIZE-X=6 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC224-G170 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-Y=0.17,SCAN-STEP-X=0.17 1 32 S ONBOARD ACQ FOR 4 K IR ,SEARCH-SIZE-Y=5,SEARCH-SIZE-X=5 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC224-G170 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC224-G170 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC224-G170 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC224-G170 FOS/BL ACCUM 1.0-PAI G160L 1 2520 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6465( 8) - 12/23/96 10:15 - [ 6] Summary Form for Proposal 6465 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-Y=1.23 SEARCH-SIZE-Y=3 SEARCH-SIZE-X=1 SEARCH-SIZE-X=6 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=2 SEARCH-SIZE-Y=5 SCAN-STEP-X=0.61 SCAN-STEP-X=0.17 SCAN-STEP-Y=0.61 SCAN-STEP-Y=0.17 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE F ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G160L ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC224-G174 NGC224-G177 NGC224-G170 ------------------------------------------------------------------------------------------------------------------------------------