CR-SPLIT has been applied to all observations at the recommendation of the review process ----- Attempting Submission 1 (Thu May 10 07:22:52 GMT 2007) ----- Phase II Proposal 11223 (RR Lyr EB Proposal) successfully submitted. ----- Attempting Submission 2 (Mon Jun 25 20:03:25 GMT 2007) ----- I believe the only errors are the decrease of observation times to their closest "legal values." All decreased values are acceptable. Resubmission of ACS Proposal # 363 Assigned ID: 1295 ----- Attempting Submission 1 (Fri Feb 09 17:30:56 GMT 2007) ----- Phase I Proposal 1295 (RR Lyr EB Proposal) successfully submitted. ----- Attempting Submission 2 (Sat Feb 10 00:03:50 GMT 2007) ----- Phase I Proposal 1295 (RR Lyr EB Proposal) successfully submitted. We are proposing HST/WFPC2 2550-10420A multi-band photometry of an important "unique" LMC eclipsing binary with an RR Lyr component. This binary is the only bona fide eclipsing binary (EB) with an RR Lyr component. Because of their constant mean luminosities (L ~ 45 Lsun; <Mv> ~ +0.5 mag) and easily recognizable light curves, RR Lyr variables have long served as the "cornerstone" of the Pop II distance scale in our galaxy and for Local Group galaxies. However, in spite of their critical importance to astronomy, there is a paucity of fundamental data available for RR Lyr stars. In fact, there are no direct measures of their most fundamental properties - such as Mass, Radius and Luminosity. The astrophysical and cosmological consequences of finding an RR Lyr star in an EB are considerable, because the masses and absolute radii of the stars of eclipsing binaries can be determined to within a few percent from time-tested analyses of their light and radial velocity curves. With accurate temperatures and ISM absorption values, determined from the proposed WFPC2 observations, it is possible to determine reliable stellar luminosities and distances. It is for these reasons that we propose WFPC2 observations of the recently discovered detached LMC eclipsing binary OGLE J052218.07-692827.4 (<V> ~18.6-mag; <B-V>0 ~+0.27; Porb = 8.9231-d); the RR Lyr primary component has a pulsation period of P(RR) = 0.564876-d. This important binary star is an integral part of our on-going multi-wavelength study of selected eclipsing binaries in nearby galaxies. Three HST/WFPC2 orbits are requested to determine complementary accurate Teff, log g and ISM absorption (A-lambda) for the component stars. These quantities will be combined with the fundamental stellar data being determined from our ground-based radial velocity and photometric observations. The combined observations will yield accurate stellar masses, radii, temperatures and luminosities, as well as a direct distance to the binary and LMC-Bar. This RR Lyr/EB thus offers the unprecedented opportunity to: (1) determine directly (and for the first time) the fundamental physical properties (M, R, L) of an RR Lyr star, (2) directly calibrate "in situ" the zero-point of the LMC RR Lyr - P - Mv - Z relation and (3) to derive an additional accurate distance to the Bar region of the LMC.

In this study we are requesting WFPC2 multi-wavelength observations of the LMC RR Lyr/EB target. This object has existing light curves and is the focus of an ongoing radial velocity program with the Magellan 6.5-m telescope at Las Campanas, as well as continuing (and improved) OGLE II/III photometry. For this proposal, 3 HST orbits are requested (the same number of orbits originally proposed for with the ACS). We have used the APT (v16.0.2) in its Phase II mode to perform detailed simulations of the exposure times and orbit planning to optimize the resulting datasets. According to the HST orbital constraints and the declination of our target, typical maximum visibilities are 3300-s per orbit. However, there are several dates where the target is within the CVZ and has ~5700-s of visibility per orbit. It would be ideal to schedule the observations during one of these times to reduce the proposal to just 2 HST orbits. Our simulations indicate that only 3 HST orbits will be sufficient to achieve full spectral coverage (UV to near-IR) with the necessary S/N to fulfill the program?s scientific goals. Also, having these images at different wavelengths will be useful for exploring the region close to the target for fainter companions that can not be resolved from the ground. Our modeling simulations indicate that the use of multi-band photometry, as proposed here (rather than spectrophotometry) only slightly degrades the determinability of temperatures, log g and A? values. This is because the proposed photometry provides a dense sampling of the spectral energy distributions. We will not be able to accurately determine metal abundances ([Fe/H]) from the proposed photometry. However, metal abundance determinations will be made from the analysis of the groundbased spectroscopy secured with the Magellan telescope for radial velocity studies. The target is relatively faint (mv ~ +18.6-mag) and has several faint stars nearby. However, we plan to use the HST/WFPC2 images to correct the ground-based photometry for possible contaminations from these fainter stars before modeling the light curves using a variant of the Wilson-Devinney Code. From previous observations, the coordinates of the proposed target are known to a precision better than + 0.2 arcsec and no problems with target acquisition are expected. It should be noted that the use of WFPC2 instead of the originally proposed ACS filter photometry does not have any significant negative impact on the proposed science. In fact, WFPC2?s long history and use in the Hubble Deep Fields have made it a well-calibrated and well-understood instrument for photometry. COOL STARS 12 false 0.0 false false false false false false SUPPORTED STAR F0-F2 J2000 05 22 18.0700 -69 28 27.40 J2000 WFPC2 Imaging No F255W WFPC2 Imaging No F300W WFPC2 Imaging No F336W WFPC2 Imaging No F380W WFPC2 Imaging No F439W WFPC2 Imaging No F555W WFPC2 Imaging No F675W WFPC2 Imaging No F814W WFPC2 Imaging No F953N WFPC2 Imaging No F1042M C:\Documents and Settings\Scott Engle\Local Settings\Temp\OPVisit349.xml 1182801654328 (Tic-Visit :proposal-id 11223 :visit-id "01" :proposal-version -1 :trans-version "20070326" :date "25-Jun-2007 16:00:53.0" :trans-errors '(:WARNINGS 6 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 627424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11223 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11223 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2880 :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 3281 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11223 :visit-id "01" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2880 :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 3281 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11223 :visit-id "01" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2880 :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 3281 :pcs-gap 0 ) true 3 0 C:\Documents and Settings\Scott Engle\My Documents\OP-cache\RR Lyr EB Proposal-v01.xml 1176413492500