The nature of short duration gamma-ray bursts (SGRBs) represents one of the great unsolved mysteries of astrophysics today. While a favoured model for their origin is in the merger of two compact objects (e.g. neutron stars) this lacks a smoking gun to date. However, these mergers are expected to create r-process elements and radioactive nickel, visible as a faint, fast transient in the days following the burst, a so-called kilonova. Recent calculations suggest much energy comes out in the near-infrared in the days following the initial burst. Here we propose for such a search in the burst GRB 130603B, the first short-GRB to have a firm redshift established directly from the afterglow. At z~0.3 the faint transient is expected to peak a few days after the burst at a H-band magnitude of ~25. Only HST has the sensitivity to detect this source, and the resolution to cleanly resolve it within its host galaxy. Our modest observations will locate, or place strong constraints on the nature of any radioactive transient associated with an prime SGRB, and may finally solve the mystery of the origin of SGRBs. If found, it will also establish that there is an alternative, un-beamed electromagnetic counterpart to binary neutron star mergers, which will have great value in the future in localising gravitational wave sources. We propose to obtain two visits of observations, targetted at GRB 130603B in two filters, one in the optical (F606W) and one in the infrared (F160W). These observations will map the evolution of the SED of the GRB with time to levels much fainter than possible from the ground, and effectively remove host galaxy contamination. In each filter we will obtain a single orbit of observation split across a 4 point dither pattern. We will place the target in ACS at the CTE1 aperture to minimize any CTE effects, in the IR it will be placed at the standard aperture close to the chip centre. We ask for visits 1 and 2 to be scheduled as soon as possible. Visits 3 and 4 should then follow several weeks later. HOT STARS Default false false false false false SUPPORTED UNIDENTIFIED GAMMA RAY EMITTER STAR FORMING REGION X-RAY EMITTER J2000 J2000 ACS/WFC Imaging No No F606W WFC3/IR Imaging No No F140W WFC3/IR Imaging No No F140W ACS/WFC Imaging No No F606W POS-TARG DITHER 0.265 LINE 0.187 false false 69.05 4 20.67 ACS-WFC-DITHER-BOX 1 false POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 2 false Timing link suitability includes constraints ([A2 After W1 by 20.0 to 40.0 days] [W2 After W1 by 20.0 to 40.0 days]) The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. 1371090498000 112.49087892168308 (Tic-Visit :proposal-id 13497 :visit-id "W1" :proposal-version -1 :trans-version "20130502" :date "10-Jun-2013 17:47:49.0" :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 1044528 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13497 :visit-id "W1" :obset-id "W1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13497 :visit-id "W1" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2840 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. 1371078270000 110.0 (Tic-Visit :proposal-id 13497 :visit-id "A1" :proposal-version -1 :trans-version "20130502" :date "10-Jun-2013 21:27:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1136896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13497 :visit-id "A1" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13497 :visit-id "A1" :orbit-number 1 :pcs-time 241 :si-vis-utilization 2910 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([W2 After W1 by 20.0 to 40.0 days]) The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13497 :visit-id "W2" :proposal-version -1 :trans-version "20130502" :date "10-Jun-2013 17:47:52.0" :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 1044528 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13497 :visit-id "W2" :obset-id "W2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13497 :visit-id "W2" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2840 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([A2 After W1 by 20.0 to 40.0 days]) The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13497 :visit-id "A2" :proposal-version -1 :trans-version "20130502" :date "10-Jun-2013 21:27:27.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1136896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13497 :visit-id "A2" :obset-id "A2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13497 :visit-id "A2" :orbit-number 1 :pcs-time 241 :si-vis-utilization 2910 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) false 1 0