14215( 2) - 06-Jul-2015 15:59:53 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14215 Version: 2 Check-in Time: 06-Jul-2015 15:59:53 STScI Edit Number: 0 Title The pristine globular cluster population of the primordial relic galaxy NGC1277 ------------------------------------------------------------------------------------ Type Cycle GO 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ignacio Trujillo Instituto de Astrofisica de Canarias Y CoI: Dr. Michael A. Beasley Instituto de Astrofisica de Canarias N CoI: Dr. Ryan Leaman Max Planck Institute for Astronomy N CoI: Dr. Mireia Montes Yale University N ------------------------------------------------------------------------------------ Abstract Galaxy mass assembly is driven dually by in-situ star formation and mergers, though which modes dominate in galaxies of different mass and at different epochs is poorly understood. These bimodal processes are thought to be mirrored in the formation mechanisms for ancient red and blue globular clusters (GC) present in massive galaxies. Whereas the red GCs are theorized to form in situ together with the core of the massive galaxy, the blue subpopulation is expected to have an external accreted origin. This scenario, however, continues presently untested. The proposed observations (2 orbits in the g and z filters using the ACS camera) will provide a direct test of this accretion hypothesis by characterizing the GC population of a massive galaxy that has survived untouched since its early assembly at z>2: NGC1277. If the accretion scenario is correct, the GC color distribution of NGC1277 will be unimodal (having only red GCs). This result would provide direct constraints on the early accretion and assembly of massive galaxies in the early universe. ------------------------------------------------------------------------------------ Observations Description ------------------------ Filter choices and photometric depth: To conduct our observations, we are asking for one orbit each in the ACS F475W (g475) and F850LP (z850) bands to image NGC1277 and its GC system. Based on its declination, NGC~1277 is visible for 57 minutes in each orbit - with overheads the total integration time on source is ~2400s. The ACS ETC suggests that with one orbit, we will reach the GC luminosity function turnover magnitude of r~26.3 with S/N~10 - allowing us to obtain the necessary number of GCs, and with sufficient photometric precision to characterize the color distribution. ------------------------------------------------------------------------------------ 14215( 2) - 06-Jul-2015 15:59:53 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-1277 GALAXY, ELLIPTICAL RA=03H19M53.5605S +/- 1", J2000 V = 13 +/- 0.1 DEC=+41D34'49.53" +/- 1" Reference Frame: Other: SIMBAD Extended: YES Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 14215( 2) - 06-Jul-2015 15:59:53 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Line_Spacing 0.187 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Angle_Between_Sides 69.05 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 14215( 2) - 06-Jul-2015 15:59:53 - [ 4] Visit: 01 Visit Requirements: ORIENT 215D TO 240 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-1277 ACS/WFC ACCUM WFC F475W 1 500 S PATTERN 1 1 see below (2280 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-1277 ACS/WFC ACCUM WFC F850LP 1 500 S PATTERN 1 2 see below (2432 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-1277 1 ACS/WFC ACCUM WFC F475W 1 none none none 1 570.0 S NGC-1277 1 ACS/WFC ACCUM WFC F475W 2 none none none 1 570.0 S NGC-1277 1 ACS/WFC ACCUM WFC F475W 3 none none none 1 570.0 S NGC-1277 1 ACS/WFC ACCUM WFC F475W 4 none none none 1 570.0 S NGC-1277 2 ACS/WFC ACCUM WFC F850LP 1 none none none 2 608.0 S NGC-1277 2 ACS/WFC ACCUM WFC F850LP 2 none none none 2 608.0 S NGC-1277 2 ACS/WFC ACCUM WFC F850LP 3 none none none 2 608.0 S NGC-1277 2 ACS/WFC ACCUM WFC F850LP 4 none none none 2 608.0 S 14215( 2) - 06-Jul-2015 15:59:53 - [ 5] Summary Form for Proposal 14215 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 215D TO 240 D, PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F475W, F850LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-1277 ------------------------------------------------------------------------------------------------------------------------------------