Assigned ID: 217 ----- Attempting Submission 1 (Thu Feb 24 23:06:48 GMT 2011) ----- This is a resubmission of our phase II proposal, id 12602. This version now includes parallel observations with ACS WFC F606 and F814. The exposure times have been adjusted to accommodate the additional buffer readouts. ----- Attempting Submission 1 (Wed Jul 06 16:42:10 GMT 2011) ----- ----- Attempting Submission 2 (Thu Jul 07 21:38:49 GMT 2011) ----- We propose to use ultra-deep near-infrared imaging with WFC3 in M4 to explore the very lowest mass domain in this globular cluster. We expect to detect the first brown dwarfs in globular clusters, and in fact perhaps the first PopII BDs anywhere. In doing so, we will also explore the hydrogen-burning limit and determine the mass-luminosity relationship around the stellar/sub-stellar border of the main sequence. In addition we will search the cluster white dwarfs for evidence of infrared excess which could herald the presence of a planetary disk or planets themselves. This ultra-deep near-IR data set will allow us to test fundamental physical predictions quantitatively for the first time. This will have important consequences for many astrophysical aspects from stellar structure and evolution, to planet formation in the early Universe, to ages, formation and evolution of GCs.

The observations will be obtained using a dither pattern so that the PSF will be well sampled. For our WFC3-IR observations, we chose a WFC3-IR-DITHER-BOX-MIN to best sample the PSF, and for our WFC3-UVIS observations we chose a combination of WFC3-UVIS-GAP-LINE and WFC3-UVIS-LINE-3PT to step over the gap between the two UVIS CCD and to sample the PSF with a 3 point dither. We split our observations into 2 visits with 4 orbits each. The first visit will be spend on 2 orbits F110W followed by 2 orbits on F390W. The first two orbits in F110W will be done with a NSAMP14 SPARS50 and the four point dither pattern. The third and forth orbit will be spent on F390W, with 911 or 922 sec individual exposure times, once on each of the three dither positions (3 exposures per orbit). The second visit will consist of 4 orbits on F160W observations, again with the WFC3-IR-DITHER-BOX-MIN to best sample the PSF, and with the same NSAMP14 SPARS50. Our deep near-IR data will be matched to the already existing optical HST ACS WFC data sets. Thus, we want to have our WFC3 IR observations within the field of view of the existing ACS WFC data, but we also want to avoid the bulk of bright stars that will be saturated in our images. The best orientation angles are thus between 30 - 65 degree or between 290 - 330 degree. The parallel observations will be done with ACS WFC F606W (2 orbits) and ACS WFC F814W (6 orbits). RESOLVED STELLAR POPULATIONS 12 false 0.0 0.0 false false false false SUPPORTED STELLAR CLUSTER GLOBULAR CLUSTER J2000 J2000 WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/UVIS Imaging No No F390W POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 1 false POS-TARG MOSAIC DITHER 3 2.414 WFC3-UVIS-DITHER-LINE-3PT false true 0.135 2 85.759 POS-TARG WFC3-UVIS-GAP-LINE 46.84 2 true 1310074500137 /tmp/OPVisit3557743218979828189.xml The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12602 :visit-id "01" :proposal-version -1 :trans-version "20110509" :date "07-Jul-2011 22:34:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 7800720 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12602 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12602 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2840 :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 12602 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2840 :al-overhead-at-end 0 :internal-dur-at-end 65 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12602 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 116 :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 12602 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3034 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 4 0 1310074450925 /tmp/OPVisit5103083633292151640.xml The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12602 :visit-id "02" :proposal-version -1 :trans-version "20110509" :date "07-Jul-2011 22:34:10.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 8725760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12602 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12602 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2840 :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 12602 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2840 :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 12602 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2840 :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 12602 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2840 :al-overhead-at-end 0 :internal-dur-at-end 851 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 4 0