We propose to use the high spatial resolution capabilities of Chandra to obtain precise positions for a sample of Gamma-ray bursts (GRBs) with no optical afterglows, where the optical light is supresssed relative to the X-ray flux. These bursts are likely to be highly obscured and may have different environments from the optically bright GRBs. Our Chandra observations will (unlike Swift-XRT positions) allow for the unique identification of a host galaxy. To locate these host galaxies we will follow up our Chandra positions with deep optical and IR observations with HST. The ultimate aim is to understand any differences between the host galaxies of optically dark and bright GRBs, and how these affect the use of GRBs as tracers of starformation and galaxy evolution at high redshift.

We propose to observe a sample of dark GRB host galaxies for bursts discovered by Swift, and subsequently located to sub-arcsecond accuracy via Chandra observations. In each case we will map the SED to provide constraints on photometric redshift and stellar population, as well as morphological information. We utillize both 4 and 6 point dithers (4 for one orbit WFPC2 observations and 6 for two orbits). COSMOLOGY 12 false 0.0 0.0 false false false false false false SUPPORTED GALAXY HIGH REDSHIFT GALAXY This is a new position, now available from Chandra observations J2000 00 00 0.0000 +00 00 0.00 J2000 GALAXY HIGH REDSHIFT GALAXY R-Magnitude: 22.0 +/- 1 J2000 23 56 4.1000 +19 36 24.10 J2000 WFPC2 Imaging No F606W WFPC2 Imaging No F606W WFPC2 Imaging No F606W WFPC2 Imaging No F606W WFPC2 Imaging No F606W NIC3 Imaging No No F160W NIC3 Imaging No No F160W NIC3 Imaging No No F160W NIC3 Imaging No No F160W NIC3 Imaging No No F160W POS-TARG DITHER 0.559017 LINE 0.559017 false false 143.1301 4 26.56505 WFPC2-BOX 1 false POS-TARG DITHER 0.265 LINE 0.187 false false 69.05 4 20.67 ACS-WFC-DITHER-BOX 2 false POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 3 false The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1237617981000 255.03267116126858 (Tic-Visit :proposal-id 11343 :visit-id "G2" :proposal-version -1 :trans-version "20080807" :date "15-Apr-2009 22:10:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 268896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11343 :visit-id "G2" :obset-id "G2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "G2" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2720 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11343 :visit-id "G2" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1237531535000 256.36716423585983 (Tic-Visit :proposal-id 11343 :visit-id "G3" :proposal-version -1 :trans-version "20080807" :date "15-Apr-2009 22:10:45.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 358528 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11343 :visit-id "G3" :obset-id "G3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "G3" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2600 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11343 :visit-id "G3" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1207409112000 223.90966644109903 (Tic-Visit :proposal-id 11343 :visit-id "A1" :proposal-version -1 :trans-version "20080807" :date "15-Apr-2009 22:10:46.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 57424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11343 :visit-id "A1" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "A1" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2735 :al-overhead-at-end 0 :internal-dur-at-end 103 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1205799393000 258.8575655424407 (Tic-Visit :proposal-id 11343 :visit-id "A2" :proposal-version -1 :trans-version "20080807" :date "15-Apr-2009 22:10:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 179264 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11343 :visit-id "A2" :obset-id "A2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "A2" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1250846430000 223.83781249807623 (Tic-Visit :proposal-id 11343 :visit-id "G4" :proposal-version -1 :trans-version "20080807" :date "10-Apr-2009 21:27:04.0" :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 11343 :visit-id "G4" :obset-id "G4" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "G4" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2774 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11343 :visit-id "G5" :proposal-version -1 :trans-version "20090702" :date "25-Aug-2009 18:52:36.0" :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 905248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11343 :visit-id "G5" :obset-id "G5" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "G5" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2624 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11343 :visit-id "G6" :proposal-version -1 :trans-version "20090702" :date "25-Aug-2009 18:52:45.0" :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 905248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11343 :visit-id "G6" :obset-id "G6" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11343 :visit-id "G6" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2624 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) true 1 0