Assigned ID: 1029 ----- Attempting Submission 1 (Sat Feb 27 01:03:10 GMT 2010) ----- PI Adrienne Cool will be out of email contact July 4-10. Please cc all correspondence to CoI's Cohn, Lugger, and Anderson, who will handle any questions that arise this week. Cohn and Lugger have a copy of the APT file and can make any necessary changes. ----- Attempting Submission 1 (Sat Jul 03 21:08:55 GMT 2010) ----- Helium-core White Dwarfs and Cataclysmic Variables in NGC 6752: New Clues to the Dynamical Evolution of Globular Clusters We propose to search for binary stars containing white dwarfs in the post-core-collapse globular cluster NGC 6752 whose unusual dynamical status has yet to be fully explained. Using F435W, F625W and F658N filters with ACS/WFC, our search will be sensitive to double-degenerate binaries of the type we have recently uncovered in NGC 6397, which contain helium-core white dwarfs (WDs) paired with probable heavy carbon-oxygen WDs. We will use He WDs found in NGC 6752 to set new constraints on binary populations in the cluster and, by comparing them to those in NGC 6397, illuminate the role of binaries in the dynamical history of both clusters. The proposed H-alpha imaging will also enable us to search for optical counterparts of numerous as-yet unidentified X-ray sources in our deep Chandra imaging; these are likely to be a mixture of cataclysmic variables (CVs), active binaries, and millisecond pulsars. We will determine whether NGC 6752 harbors a class of very faint CVs as have been recently found in the field and in NGC 6397. Those in NGC 6397 have been interpreted as an old population that formed near the cluster center and migrated outward as it aged, in contrast to the bright young CVs that reside close to the center. We will test for a similar pattern of spatial distribution with CV magnitude in NGC 6752.
This program uses ACS/WFC as the primary SI to observe the central regions of the globular cluster NGC 6752. WFC3/UVIS is used in parallel to obtain images of six different fields in the outer regions of the cluster. We have divided the 12-oribt program into six 2-orbit visits, each at a different ORIENT, in order to align the parallels with archival data (so that proper motions, required for our science goals, can be measured). Within each 2-orbit visit, the WFC exposures consist of 1 short (10s) and 2 long (360s) exposures in F625W, 1 short (10s) and 2 long (380s) exposures in F435W, and 4 long (724-820s) exposures in F658N. The exposure times for the shorts in the broad-band filters are chosen to minimize saturation of HB and RGB stars while providing S/N>~100 for stars that just saturate in the long exposures. Within each 2-orbit visit, the UVIS exposures consist of 4 long exposures in F625W and 4 long exposures in F438W. We have packed exposures into the orbits in such a way as to make the sets of exposures with a given filter as close to equal in length as possible. Constraints resulting from varying overheads, buffer dumps, etc, are such that the match is good to about 15%. We use the WFCENTER aperture in order to obtain the best possible overlap between WFC images that will be taken at the six different ORIENTs. For the first orbit of each visit, POSTARG values are chosen so that the cluster core (radius ~ 10") will lie entirely on WFC1 (Y shift of -9"). In the second orbit, we place the entire core on the other side of the chip gap (on WFC2) using a Y shift of +13.5". Within each orbit, we use two dither positions. The second is offset from the first by (dx, dy) = (3.5, 4.5) WFC pixels. The resulting shift in the parallel exposures will be (dx, dy) = (1.42, -7.37) according to our calculations. This will provide the best possible sampling of the PSF in WFC and reasonably good sampling in UVIS as well. We found this to be the best combination that involved shifts of at least 1.5 and no more than 4.5 WFC pixels. Our science goals require that the parallel exposures coincide with existing archival data. This requirement is the primary driver for the choices of ORIENTs for the six visits. A secondary consideration is that we want the diffraction spikes to appear at different angles in each visit (offsets >8-10 degrees) in order to maximize the number of stars that we can measure well in the complete dataset. In choosing ORIENT ranges for each visit we have carefully considered these factors as well as the degree to which widening the range increases the number of days in which the visit is schedulable. Results are shown below: visit field ORIENT days 1 A 314-317 9 2 B 284 14 3 E 111-118 4 4 F 78-80 21 5 G 55 36 6 H 36 20 We note that the optimum ORIENT for field E (118D) results in 0 schedulable days. We have extended the range in the one direction that increases schedulability according to APT, by as far as we could without excessive loss of overlap with archival data. RESOLVED STELLAR POPULATIONS 12 false 0.0 0.0 false false false false false false SUPPORTED STELLAR CLUSTER GLOBULAR CLUSTER Center coordinate as determined by Ryan Gosbury from Sarajedini ACS images. Agrees well with Ferraro et al. 2003 from WFPC2 images and Harris catalog. J2000 19 10 51.7800 -59 58 54.70 J2000 ACS/WFC Imaging No No F435W ACS/WFC Imaging No No F625W ACS/WFC Imaging No No F658N C:\Documents and Settings\cool\My Documents\RESEARCH\PROPOSALS\hst\cycle18\6752\PHASEII\OP-cache\GO-12254_phaseII_FINAL-v01.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12254 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "02-Jul-2010 20:58:44.0" :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 5152224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12254 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12254 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3178 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12254 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0 C:\Documents and Settings\cool\My Documents\RESEARCH\PROPOSALS\hst\cycle18\6752\PHASEII\OP-cache\GO-12254_phaseII_FINAL-v02.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12254 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "02-Jul-2010 20:59:13.0" :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 5152224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12254 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12254 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3178 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12254 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0 C:\Documents and Settings\cool\My Documents\RESEARCH\PROPOSALS\hst\cycle18\6752\PHASEII\OP-cache\GO-12254_phaseII_FINAL-v03.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12254 :visit-id "03" :proposal-version -1 :trans-version "20100505" :date "02-Jul-2010 21:00:11.0" :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 5152224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12254 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12254 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3178 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12254 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0 C:\Documents and Settings\cool\My Documents\RESEARCH\PROPOSALS\hst\cycle18\6752\PHASEII\OP-cache\GO-12254_phaseII_FINAL-v04.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12254 :visit-id "04" :proposal-version -1 :trans-version "20100505" :date "02-Jul-2010 21:00:29.0" :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 5152224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12254 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12254 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3178 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12254 :visit-id "04" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0 C:\Documents and Settings\cool\My Documents\RESEARCH\PROPOSALS\hst\cycle18\6752\PHASEII\OP-cache\GO-12254_phaseII_FINAL-v05.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12254 :visit-id "05" :proposal-version -1 :trans-version "20100505" :date "02-Jul-2010 21:00:48.0" :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 5152224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12254 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12254 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3178 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12254 :visit-id "05" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0 C:\Documents and Settings\cool\My Documents\RESEARCH\PROPOSALS\hst\cycle18\6752\PHASEII\OP-cache\GO-12254_phaseII_FINAL-v06.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12254 :visit-id "06" :proposal-version -1 :trans-version "20100505" :date "02-Jul-2010 21:01:07.0" :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 5152224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12254 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12254 :visit-id "06" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3178 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12254 :visit-id "06" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0