The differing environments of dark gamma-ray bursts

Please find attached our new submission for 12378, which should specify all the remaining orbits to two bursts (a further observation of GRB 110328A and 2 orbits of observations of GRB 110709B). While we have not specified any specific timing requests, for GRB 110709B it would be ideal if it could be conducted in early November. The reason for this is because this burst is gathering significant interest. It was particularly dark, and possibly "repeated". Chandra observations revealed that there are two sources consistent with the afterglow position from Swift, raising the possibility of a lensed burst. A second Chandra epoch is scheduled for the second week in November. HST observations at roughly the same time would therefore be most valuable. However, we accept that we did not formally ask for timing windows in the phaseI proposal, and so have not implemented any directly in the phase II. We are also aware of the pressues of HST scheduling at present, so and so understand that it may not be possible to accomodate the above request. Please let me know if you have any further questions or need clarifications on anything above. ----- Attempting Submission 1 (Mon Sep 20 14:12:14 GMT 2010) ----- ----- Attempting Submission 2 (Tue Jun 28 14:15:08 GMT 2011) ----- ----- Attempting Submission 3 (Mon Jul 18 12:34:34 GMT 2011) ----- ----- Attempting Submission 4 (Fri Sep 30 16:59:51 GMT 2011) ----- The differing environments of dark gamma-ray bursts Dark gamma-ray bursts (GRBs) -- where the optical emission is apparently suppressed -- can only be reliably localized by their X-ray afterglows. Here we propose to complete a survey using the sensitivity and point spread function of Chandra to precisely pinpoint the GRB locations, and HST to locate and study the host galaxies. Our results to date are suggestive of dark GRBs originating in more luminous and (so far exclusively) merging galaxies. Our increased sample will allow us to make strong statistical statements as to these differences and so elucidate both the nature of dark GRBs, and the relationships between GRBs and both obscured and unobscured star formation.

The aim of this programme is to obtain HST optical and IR observations of the host galaxies of dark GRBs in order to characterize their morphologies and magnitudes in the optical and IR. We will utilize one of two strategies, depending on the outcome of our optical afterglow searches. i) if the searches are unsucessful at finding an afterglow (i.e. show the burst is dark), but do suggest a host galaxy we will obtain WFC3 F606W and F160W observations in a single orbit observation ii) If deep optical observations do not show a candidate host we will observe a single orbit in ACS/F606W and WFC3/F160W to achieve extra depth. For our single orbit two colour observations we will utilize a 3 point dither to provide the best compromise between dithering/cosmic ray rejection and depth. Our full orbit per colour observations will use a standard 4 point dither. 12 false 0.0 0.0 false false false false SUPPORTED EXT-STAR X-RAY TRANSIENT This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 UNIDENTIFIED GAMMA RAY EMITTER J2000 GALAXY HIGH REDSHIFT GALAXY J2000 WFC3/UVIS Imaging No No F606W WFC3/IR Imaging No No F160W WFC3/UVIS Imaging No No F606W WFC3/IR Imaging No No F160W WFC3/UVIS Imaging No No F606W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 4

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POS-TARG DITHER 0.636 LINE false false 3 41.788 WFC3-IR-DITHER-LINE 5

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POS-TARG DITHER 0.145 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE 2

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POS-TARG DITHER DITHER 2 0.135 WFC3-UVIS-MOS-DITH-LINE false true 0.0992 3 46.84 POS-TARG WFC3-UVIS-MOS-DITH-LINE 3.93 6

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The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317401922005 /private/var/folders/S9/S94diLVQHr89dEkE+FrTHE+++TI/-Tmp-/OPVisit6020820579491465409.xml (Tic-Visit :proposal-id 12378 :visit-id "D1" :proposal-version -1 :trans-version "20110811" :date "30-Sep-2011 17:58:41.0" :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 1388512 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12378 :visit-id "D1" :obset-id "D1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12378 :visit-id "D1" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2896 :al-overhead-at-end 0 :internal-dur-at-end 616 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317401926569 /private/var/folders/S9/S94diLVQHr89dEkE+FrTHE+++TI/-Tmp-/OPVisit3484827759764271601.xml 1312437735000 122.03373761766687 (Tic-Visit :proposal-id 12378 :visit-id "D2" :proposal-version -1 :trans-version "20110811" :date "30-Sep-2011 17:58:45.0" :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 2359184 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12378 :visit-id "D2" :obset-id "D2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12378 :visit-id "D2" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3157 :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 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12378 :visit-id "D2" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3272 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317401929163 /private/var/folders/S9/S94diLVQHr89dEkE+FrTHE+++TI/-Tmp-/OPVisit7770734573629901658.xml (Tic-Visit :proposal-id 12378 :visit-id "D3" :proposal-version -1 :trans-version "20110811" :date "30-Sep-2011 17:58:48.0" :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 1388512 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12378 :visit-id "D3" :obset-id "D3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12378 :visit-id "D3" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2899 :al-overhead-at-end 0 :internal-dur-at-end 616 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 1 0 Awaiting Dark GRB position from Chandra The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317401931270 /private/var/folders/S9/S94diLVQHr89dEkE+FrTHE+++TI/-Tmp-/OPVisit5738408233409521322.xml (Tic-Visit :proposal-id 12378 :visit-id "W1" :proposal-version -1 :trans-version "20110811" :date "30-Sep-2011 17:58:50.0" :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 12378 :visit-id "W1" :obset-id "W1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12378 :visit-id "W1" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2840 :al-overhead-at-end 0 :internal-dur-at-end 521 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3249 :pcs-gap 0 ) true 1 0 Awaiting dark GRB trigger The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317401933931 /private/var/folders/S9/S94diLVQHr89dEkE+FrTHE+++TI/-Tmp-/OPVisit8328106041341550267.xml (Tic-Visit :proposal-id 12378 :visit-id "W2" :proposal-version -1 :trans-version "20110811" :date "30-Sep-2011 17:58:53.0" :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 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12378 :visit-id "W2" :obset-id "W2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12378 :visit-id "W2" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2872 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3249 :pcs-gap 0 ) true 1 0 Awaiting dark GRB trigger