0 Assigned ID: 15 ----- Attempting Submission 1 (Fri Mar 20 18:16:41 GMT 2015) ----- This is a resubmission of the Phase II for this programme. According to the suggestions of the contact scientist we added a 20e- FLASH to our short ACS exposures. 414738450 ----- Attempting Submission 1 (Fri Mar 27 14:49:29 GMT 2015) ----- HST Phase II Proposal 14061 (ter5_phase2_2.apt) successfully submitted. Receipt: # 14061-1 ----- Attempting Submission 3 (Sat Apr 04 17:01:36 GMT 2015) ----- Low mass X-ray binaries (LMXBs) and radio Millisecond Pulsars (MSPs) are thought to be the initial and ending points of the evolution of a binary system where a neutron star accretes matter from a companion. Many crucial phases of this scenario still need to be understood. For instance, Papitto et al. (2013, Nature, 501, 517) provided the first evidence of a system currently swinging between the X-ray and the radio emission states, thus showing that an intermediate phase marks the transition from a LMXB to a MSP. The X-ray properties of that object closely resemble those of EXO 1745-248, a transient LMXB located in Terzan 5, which therefore promises to be another system marking the LMXB-MSP transition. On March 13, 2015, SWIFT detected an X-ray burst in Terzan 5 at a location that may be consistent with the coordinates of EXO 1745-248. However, the error circle is still too large (2"-3") to exclude other possibilities. Since the thermonuclear burning runway at the origin of the X-ray burst is expected to produce also a significant enhancement of the optical luminosity, here we propose to invest 2 HST orbits to acquire deep optical images of the region. The comparison between these images (secured during the outburst) and those already available (acquired during quiescence) will immediately pinpoint the source, thus offering a unique opportunity to identify the object, determine precisely its coordinates and possibly confirm its association to EXO 1745-248. The optical emission is expected to fade by ~1mag after 1-2 months from the burst. Hence, the proposed DDT observations represent indeed a unique but temporary opportunity to catch a MSP in its pre-birth phase. The observations are organized in one visit of 2 orbits. In each orbit we require one short exposure (10 sec in F814W and 50 sec in F606W) and 5 long exposures (~372 sec in F814W and ~398 sec in F606W). Dithering is performed by applying small offsets (via POS TARG keyword) to each exposure, adopting a path similar to that used in GO 12933. For each orbit we also planned two parallel WFC3-UVIS exposures (with F814W in the first orbit and F606W in the second orbit). In order to duplicate the field of view of previous observations (Prop GO9799-PI Rich and GO12933-PI Ferraro), we adopted the WFC2 aperture and a proper ORENTATION (ORIENT 271.075287D). Note that, according to the Visit Planner, the required ORIENTATION has little impact on the observations schedulability. We emphasize that, beacuse of the transient nature of the target, the observations need to be performed as soon as possible, nominally before May 31 2015 (see Timing Requirements). However, according to the Visit Planner, one visit of 2 full orbits on the target (Terzan 5) can be executed only between April 10 and April 27, 2015 (independently of the ORIENTATION). RESOLVED STELLAR POPULATIONS 0 Regular false false false false false SUPPORTED STELLAR CLUSTER GLOBULAR CLUSTER J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W 1428156069764 /Users/cristina/LAVORO/PROPOSAL/DDTHST/TER5_PHASE2/OP-cache/ter5_phase2_4-v01.xml The scheduling data was generated by CASM 23.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14061 :visit-id "01" :proposal-version -1 :trans-version "20150128" :date "04-Apr-2015 16:01:09.0" :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 4565664 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14061 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14061 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2899 :al-overhead-at-end 85 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3232 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14061 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3010 :al-overhead-at-end 94 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3232 :pcs-gap 0 ) true 2 0