0 Assigned ID: 949 ----- Attempting Submission 1 (Fri Apr 07 21:48:45 GMT 2017) ----- 0 ----- Attempting Submission 1 (Thu Jul 20 20:07:47 GMT 2017) ----- HST Phase II Proposal 15087 (targetconfirmation.apt) successfully submitted. Receipt: # 15087-1 ----- Attempting Submission 5 (Tue Sep 26 22:57:10 GMT 2017) ----- Star Cluster Populations of Interacting Dwarf Galaxies We propose high spatial resolution optical, UV, and narrowband Ha imaging of 6 nearby pairs of dwarf galaxies with enhanced star formation likely driven by a dwarf-dwarf interaction. Dwarf-dwarf interactions dominate galaxy interactions at all redshifts, making this environment essential to our understanding of galaxy assembly and star formation throughout the universe. However, little is known about how galaxy mergers proceed at low mass. The high resolution observations proposed here will resolve individual star clusters (a goal not currently possible from the ground) to explore the role of tidal interactions in triggering clumpy star formation and in promoting the formation of massive star clusters in low metallicity environments. This mode of cluster formation was likely dominant during early galaxy assembly, and the extent to which star formation is clumped is predicted to play a role in the extent to which feedback impacts the interstellar medium. Our sample of isolated dwarf-dwarf interactions offers the only opportunity for a high resolution view of this mode of cluster formation outside the influence of a massive galaxy host. We aim to obtain WFC3/UVIS broadband optical (F621M and F814W), UV (F336W), and narrowband (F665N) imaging for 6 interacting dwarf pairs to resolve individual star clusters and thus determine accurate ages, masses, and distributions. The medium-band F621M images will be used to subtract the continuum to measure Ha fluxes from the (redshifted) narrowband F665N images, in addition to providing an additional data point on the SED. One WFC3/UVIS field of view can be used to observe both dwarfs simultaneously for 5 of the 6 target pairs, but the remaining pair will require two fields of view. To detect clusters of Mstar ~ 10^4 Msun as old as 100 Myr at the distance of our pairs (20-40 Mpc), we set our sensitivity requirement using the magnitudes predicted for clusters of that mass and age by Starburst99 models. Starburst99 predicts an absolute V band magnitude of -10.5. To achieve S/N ratios of 40-50 for this magnitude, the ETC determines that we can reach this level of sensitivity in ~25, 9, 4, and 4 minutes of integration time in the Ha (F665N), U (F336W), mediumband (F621M), and I (F814W) broadband respectively at a distance of 20 Mpc which we then scale to the distances of our dwarf pairs. By combining the narrowband Ha and broadband I observations into one orbit (per individual dwarf or dwarf pair) and by combining the broadband U and mediumband optical observations into a second orbit, we have 10-15 minutes remaining per orbit for overhead (including an estimate of 6 minutes to acquire and an additional 0.5 minutes per dither). To make our program as efficient as possible, we place no constraints on the timing or the roll angle of the observations. These are not coordinated observations. Galaxies and the IGM 6 false false true false false false false SUPPORTED GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 J2000 GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 J2000 GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 J2000 GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 J2000 GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 J2000 GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 J2000 GALAXY AMORPHOUS IRREGULAR INTERACTING GALAXY STAR FORMING REGION J2000 WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F621M WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F665N The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of merging dwarf galaxies that fit into one chip (UVIS2). We opt for a C4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. The merging system fits easily within the chip so all orientation angles are acceptable. (Tic-Visit :proposal-id 15087 :visit-id "01" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:05.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3217 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2943 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3217 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of merging dwarf galaxies that fit into one chip (UVIS2). We opt for a C4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. The merging system fits easily within the chip so all orientation angles are acceptable. (Tic-Visit :proposal-id 15087 :visit-id "13" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "13" :obset-id "13" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "13" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3217 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "13" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2943 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3217 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of dwarf galaxies that span both chips. We opt for a B4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. At some orient angles, the chip gap falls across either of our pair members so we avoid those. (Tic-Visit :proposal-id 15087 :visit-id "03" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:12.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2864 :al-overhead-at-end 123 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3225 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2958 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3225 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of dwarf galaxies that span both chips. We opt for a B4 (4-point) dither pattern for the longest exposure in filter F657N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. At some orient angles, the chip gap falls across either of our pair members so we avoid those. (Tic-Visit :proposal-id 15087 :visit-id "16" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:17.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "16" :obset-id "16" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "16" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2844 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3260 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "16" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2958 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3260 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of dwarf galaxies that span both chips. We opt for a B4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. At some orient angles, the chip gap falls across either of our pair members so we avoid those. dm1225+50-VISIT2 is a duplicate of dm1225+50-VISIT1. (Tic-Visit :proposal-id 15087 :visit-id "05" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3001 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3393 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "05" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3123 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3393 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of dwarf galaxies that span both chips. We opt for a B4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. At some orient angles, the chip gap falls across either of our pair members so we avoid those. dm1225+50-VISIT2 is a duplicate of dm1225+50-VISIT1. (Tic-Visit :proposal-id 15087 :visit-id "14" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:22.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "14" :obset-id "14" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "14" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3001 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3393 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "14" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3123 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3393 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of dwarf galaxies that span both chips. We opt for a B4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. At some orient angles, the chip gap falls across either of our pair members so we avoid those. dm1237+18-VISIT2 is a duplicate of dm1237+18-VISIT1. 1518211877000 272.32521008663196 (Tic-Visit :proposal-id 15087 :visit-id "08" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "08" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3216 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "08" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2973 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3216 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image the pair of dwarf galaxies that span both chips. We opt for a B4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. At some orient angles, the chip gap falls across either of our pair members so we avoid those. dm1237+18-VISIT2 is a duplicate of dm1237+18-VISIT1. (Tic-Visit :proposal-id 15087 :visit-id "15" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:28.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "15" :obset-id "15" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "15" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3216 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "15" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2973 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3216 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image a single dwarf galaxy that is a member of a pair and that fits into one chip (UVIS2). We opt for a C4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. The dwarf fits within the chip so all orientation angles are acceptable. (Tic-Visit :proposal-id 15087 :visit-id "10" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "10" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3205 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "10" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2958 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3205 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We aim to image a single dwarf galaxy that is a member of a pair and that fits into one chip (UVIS2). We opt for a C4 (4-point) dither pattern for the longest exposure in filter F665N, a WFC3-UVIS-DITHER-LINE-3PT (3-point) dither pattern for the medium length exposure in filter F336W, and a WFC3-UVIS-DITHER-LINE (2-point) dither pattern for the shortest length exposures in filters F621M and F814W to minimize overhead. The dwarf fits within the chip so all orientation angles are acceptable. 1527790963000 248.5449419113557 (Tic-Visit :proposal-id 15087 :visit-id "11" :proposal-version -1 :trans-version "20170613" :date "26-Sep-2017 15:53:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3176256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15087 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15087 :visit-id "11" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 121 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3205 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15087 :visit-id "11" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2958 :al-overhead-at-end 122 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3205 :pcs-gap 0 ) false 2 0