Had to shorten the exposures by 3 sec. each. Overheads must have changed, and now the orbits are too long. Cut exp. 3 on visit 2 as well. ----- Attempting Submission 2 (Thu Feb 18 14:01:29 GMT 2010) ----- HST Phase II Proposal 11711 (11711.apt) successfully submitted. ----- Attempting Submission 3 (Thu Feb 18 14:26:25 GMT 2010) ----- A Definitive Distance to the Coma Core Ellipticals As the richest galaxy cluster in the local universe (cz < 10,000 km/s), the Coma cluster continues to serve as the standard of comparison for numerous studies of galaxy properties and scaling relations in clusters. The central importance of Coma has been recognized with two recent HST large programs: a Treasury survey to study the dwarf galaxy population by imaging 82 different ACS/WFC pointings, and a program to measure Cepheid distances to two spiral galaxies projected within the Coma core region. An accurate distance to the Coma core is essential for comparing the galaxy luminosities and sizes to nearby galaxies in Virgo and Fornax, while an accurate peculiar velocity is needed for correctly tying to more distant clusters. However, experience dictates that Cepheid distances to clusters must be carefully verified against accurate measurements to the dominant early-type population, especially for such an unprecedented effort as the Coma Cepheid search (the completion of which remains uncertain). We propose to measure highly accurate (3-4% internal error per galaxy) SBF distances to the two giant Coma core ellipticals. The reliability of the SBF method with the ACS/WFC has been repeatedly demonstrated, and it is so efficient that it requires only 3% of the number of orbits dedicated to the two current large Coma programs. The precise ACS SBF Coma core distance will also provide a good constraint on the Coma peculiar velocity, thus improving the accuracy of comparisons to distant clusters. Finally, our program will answer some longstanding puzzles surrounding the rich globular cluster population in the core of this archetypal galaxy cluster.
We will target the two giant galaxies, NGC4874 and NGC4889, that define the core of the Coma cluster and measure their distances using the SBF method in the F814W bandpass of the ACS/WFC. S/N calculations show that we need at least four orbits in F814W to measure a reliable SBF signal. In addition, calibration of the SBF measurement to an absolute scale requires an accurate galaxy color. We will use F475W for the second bandpass, and thus calibrate the F814W SBF magnitude using F475W-F814W. To measure an accurate color for the SBF calibration requires one additional orbit with F475W, or five orbits in total per galaxy for the SBF observations. Another goal of our program is to obtain an accurate census of the globular cluster population and its color distribution. To obtain reasonably accurate colors at the peak of the GCLF requires at least 2 orbits of F475W integration, in addition to the deep F814W observations dictated by the SBF requirements. Thus, the total requirement to carry out our science program is four orbits in F814W and two orbits in F475W per galaxy. We can use one orbit's worth of archival ACS/WFC F475W data on NGC4874 for our purposes, reducing our total program to 11 orbits. We also have coordinated parallels with WFC3. For the NGC4889 observations (visits 2 and 3), we will place the WFC3/IR aperture on NGC4874 and image the latter galaxy in parallel in the F110W and F160W bandpasses. For the NGC4874 primary observations (visit 1), we will image a random parallel field with the F475X and F600LP bandpasses of WFC3/UVIS (it is not possible to image NGC4889 in parallel because the necessary orientation cannot be scheduled). UNRESOLVED STELLAR POPULATIONS AND GALAXY STRUCTURE 12 false 0.0 0.0 false false false false false false SUPPORTED GALAXY ELLIPTICAL This object was generated by the targetselector and retrieved from the NED database. J2000 12 59 35.7000 +27 57 34.00 J2000 GALAXY ELLIPTICAL This object was generated by the targetselector and retrieved from the NED database. J2000 13 00 8.1000 +27 58 37.00 J2000 ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W POS-TARG DITHER 1.5 LINE false false 3 85.28 ACS-WFC-DITHER-LINE 1 false POS-TARG DITHER DITHER 3 0.275 pattern & subpattern define a 4x3 grid of pointings. LINE false false 1.5 4 0.0 POS-TARG ACS-WFC-DITHER-LINE 85.28 2 true The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1267180511000 227.4518013 (Tic-Visit :proposal-id 11711 :visit-id "01" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 18:02:03.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 8594624 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11711 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11711 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2932 :al-overhead-at-end 21 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "01" :orbit-number 2 :pcs-time 195 :si-vis-utilization 3072 :al-overhead-at-end 21 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "01" :orbit-number 3 :pcs-time 195 :si-vis-utilization 3072 :al-overhead-at-end 8 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "01" :orbit-number 4 :pcs-time 195 :si-vis-utilization 3072 :al-overhead-at-end 8 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "01" :orbit-number 5 :pcs-time 195 :si-vis-utilization 3072 :al-overhead-at-end 8 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) true 5 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /private/tmp/OPVisit4063792707231141640.xml (Tic-Visit :proposal-id 11711 :visit-id "02" :proposal-version -1 :trans-version "20091209" :date "18-Feb-2010 09:25:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 8389296 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11711 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11711 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2923 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2985 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2946 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2946 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11711 :visit-id "02" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2946 :al-overhead-at-end 0 :internal-dur-at-end 808 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 5 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /private/tmp/OPVisit4392722196083040990.xml (Tic-Visit :proposal-id 11711 :visit-id "03" :proposal-version -1 :trans-version "20091209" :date "18-Feb-2010 09:00:12.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1636064 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11711 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11711 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2923 :al-overhead-at-end 0 :internal-dur-at-end 1055 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 1 0