0 Assigned ID: 1516 ----- Attempting Submission 1 (Fri Mar 01 15:53:12 GMT 2013) ----- HST Phase I Proposal 1516 (MILONEetalNGC18562013.apt) successfully submitted. ----- Attempting Submission 2 (Mon Mar 04 13:18:19 GMT 2013) ----- 0 ----- Attempting Submission 1 (Wed Jun 26 09:48:22 GMT 2013) ----- ----- Attempting Submission 2 (Thu Nov 14 08:59:34 GMT 2013) ----- no orient with parallel is ok. Multiple stellar populations in the young Large Magellanic Cloud cluster NGC1856 The recent discovery of multiple sequences in the color-magnitude diagram of Galactic globular clusters have demonstrated that star clusters have experienced a complex star-formation history. Apparently, the only way to explain the main sequence splitting appears to be the product of hot CNO burning, including He, which can be enriched up to an astonishingly high Y~0.40. Recent discoveries have demonstrated that the CMDs of a large fraction of intermediate-age clusters in the Magellanic Clouds (~70 %) are not consistent with the simple, single stellar population hypothesis. The conditions under which star clusters experience the formation of multiple generations remain controversial. A breakthrough understanding of the problem can be provided by the young stellar clusters, where second generation of stars may be forming, or just formed. However, these objects have been poorly studied to date. To properly constraint the multipopulation phenomenon, we propose deep UVIS imaging of the ~300 Myrs old LMC star cluster NGC 1856 which, according to a recent study, is the best candidate to host multiple stellar populations. The proposed observations will allow us to accurately measure possible age difference between the stellar populations providing fundamental clues on the formation mechanism. Our simulations of WFC3 performance suggest that our observing strategy allow us to detect a main sequence split caused by an He difference as small as Delta Y ~0.03. This is a proposal aimed at obtaining high accuracy photometry of the MC cluster NGC 1856 in the UV WFC3/UVIS/F336W and optical WFC3/UVIS/F814W bands. RESOLVED STELLAR POPULATIONS 12 false true 0.0 0.0 false false false SUPPORTED STELLAR CLUSTER GLOBULAR CLUSTER This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W /tmp/OPVisit7828657889975175536.xml The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. NGC-1856 - part 1 (Tic-Visit :proposal-id 13379 :visit-id "01" :proposal-version -1 :trans-version "20130919" :date "14-Nov-2013 09:31:49.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13379 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13379 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2724 :al-overhead-at-end 122 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3057 :pcs-gap 0 ) true 1 0 /tmp/OPVisit5912384319480836432.xml The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. NGC-1856 - part 1 (Tic-Visit :proposal-id 13379 :visit-id "02" :proposal-version -1 :trans-version "20130919" :date "14-Nov-2013 09:30:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13379 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13379 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2724 :al-overhead-at-end 122 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3057 :pcs-gap 0 ) true 1 0 /tmp/OPVisit1657311982648673444.xml The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. NGC-1856 - part 1 (Tic-Visit :proposal-id 13379 :visit-id "03" :proposal-version -1 :trans-version "20130919" :date "14-Nov-2013 09:33:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13379 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13379 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2724 :al-overhead-at-end 122 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3057 :pcs-gap 0 ) true 1 0 /tmp/OPVisit7281565724583825746.xml The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. NGC-1856 - part 1 (Tic-Visit :proposal-id 13379 :visit-id "04" :proposal-version -1 :trans-version "20130919" :date "14-Nov-2013 09:34:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13379 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13379 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2724 :al-overhead-at-end 122 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3057 :pcs-gap 0 ) true 1 0