! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 6121,v 6.1 1995/04/06 20:12:24 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Christian Ready ! Phone: 410 338-4546 , E-mail: ready@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Date generated: Mon Dec 19 08:23:28 EST 1994 ! Proposal_Information ! Section 4 Title: UV Photometry of the Degenerate X-ray Binary in NGC6712 Proposal_Category: GO Scientific_Category: Hot Stars Cycle: 5 Investigators PI_name: Phil Charles PI_Institution: Oxford University CoI_Name: Lydie Koch-Miramond CoI_Institution: CEN SACLAY Contact: ! Y or N (designate at most one contact) CoI_Name: Michel Auriere CoI_Institution: Observatoire de Pic-du-Midi Contact: ! Y or N (designate at most one contact) CoI_Name: Tim Naylor CoI_Institution: University of Keele Contact: ! Y or N (designate at most one contact) CoI_Name: Jan van Paradijs CoI_Institution: University of Amsterdam Contact: ! Y or N (designate at most one contact) CoI_Name: Andy Martin CoI_Institution: University of Oxford Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) Ground-based imaging has revealed the optical counterpart of the luminous X- ray binary in the globular cluster NGC6712. It is a faint UV star with an indication of up to 0.4 mag variability. However, at B=21.2 and crowded by two brighter stars within 1 arcsec, only HST WFPC photometry will enable a detailed light curve of the X-ray source to be obtained. Given the distance to the cluster the X-ray source has M_V=5.6 which makes it a prime candidate for an underluminous and hence degenerate secondary. The orbital period will thus lie below 80 mins and is likely to be in the range 10--60 mins. With evidence already for variability we propose here for time -resolved CCD photometry to measure the orbital period and light curve in the UV, and thus confirm its degenerate nature. This would be a remarkable result as 2 of the 3 identified (optical/UV) sources in globular clusters would be degenerate, with important implications for the formation and evolution of globular cluster X-ray binaries. Questions ! Free format text (please update) Observing_Description: Time-resolved WFPC2 exposures using PC1 and filter F336W. With 5 min exposures and 3 min overhead we can obtain 6 observations per HST orbit after the initial acquisition. The observations need to be scheduled over 9 contiguous orbits in order for maximum sensitivity to detecting the orbital modulation. A subsequent (single) set of UBVRI images (using F336W, F439W, F555W, F675W and F814W) can be performed at any time. Exposure times for comparable signal to noise are 300, 300, 60, 60, 60 respectively. This can be accomplished in a single orbit. Real_Time_Justification: Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: NGC6712 Alternate_Names: NGC6712-STAR-S, X1850-086 Description: STAR, LMXB, STELLAR CLUSTER, GLOBULAR CLUSTER Position: RA=18H 50M 21.07S +/- 0.5", ! Most common specification format is DEC=-08D 46' 05" +/- 0.5", ! RA=0H 0M 0.00S +/- 0S, ! DEC=0D 0' 0.0" +/- 0", ! PLATE-ID=0000 Equinox: 1950 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=21.0+/-0.3, B-V=0.0+/-0.5 Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling PCS MODE Fine ! GUIDing TOLerance ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN