change pos-targ from 6.2, -12 to -8.0, -5.4 at Ron's request. ----- Attempting Submission 14 (Tue Jan 15 18:18:21 GMT 2008) ----- We propose to measure the radius of the recently-discovered transiting extrasolar planet XO-1b. XO-1b's nominal radius is 1.30 times the radius of Jupiter, which is nearly as large as HD 209458b (1.32 R_J). We will use two independent methods to measure XO-1b's radius: 1) precision light curve analysis, and 2) measurement of its trigonometric parallax combined with its spectroscopically-determined effective temperature and its apparent magnitude.

To observe the transit light curve, we propose 8 orbits of HST ACS/HRC observations of X0-1 in two visits. To determine the distance to X0-1 trigonometrically, we propose 6 orbits of HST FGS observations spread over three epochs. With ACS we propose to observe XO-1b during two visits with the HRC using the grism G800L. Observations will be obtained at extremely high S/N in a time-series mode with a cadence of 95 seconds. The first HST orbit of each visit will be phased to proceed a transit of XO-1b, orbits 2 and 3 in transit, and the 4th and final orbit provides out-of-transit normalization in combination with orbit 1. The science goals for the ACS observations closely parallel the prime goal of the ``original" HST program on HD 209458, the GO/DD 8789 to provide a much cleaner transit light curve, than possible from the ground, in order to firm up system parameters. For this prime goal 8789 used STIS with the G750M grating in place as a ``light bucket", by dispersing the light over many pixels it was possible to count over 10E8 e- per exposure, and thus reach time-series S/N of 10,000. Given the $V$ = 7.64 magnitude of HD 209458, even the 570 \AA\ range of G750M at low-intrinsic efficiency provided 1.55 $\times \,10^8$ e- per 60 s integration. Using the ACS/HRC grism to disperse the light of XO-1 over about 200 pixels allows collection of 5 $\times 10^7$ e- per 60-s exposure while staying 25\% under saturation. Given the much higher efficiency of the G800L on ACS than the medium resolution STIS grating, and that XO-1b is 3.7 ($V$) magnitudes fainter than HD 209458, it makes perfect sense to switch from STIS to ACS (independent of the STIS loss). Although fainter by $\times$25 in the relevant bandpass, XO-1's count rate with HRC/G800L is only $\times$3.1 lower than the original HD 209458 STIS observations. Adopting an exposure time of 60 s, using the 512 square subarray nearest the readout Amp for HRC provides an overhead of 35 s per read, and still encompasses the full zeroth, and first orders from G800L. With a 95s cycle time it is possible to maintain 63\% observing efficiency on XO-1b, which compares quite favorably to the 75\% with HD 209458. The S/N per HST orbit provided by ACS/HRC will be a factor of $\times$2 times lower than that realized for the much brighter HD 209458. Thus, the overall light curve we will obtain on XO-1b will still be stunning, with $\sim$220 exposures in total over the two, four-orbit visits with each exposure at a S/N of 7,000. The broad bandpass coverage will provide extra constraints via quantifying the color dependence of limb darkening. From a technical perspective these observations of a $V$ = 11.2 star with transiting planet will provide a major step to outlining what science can be accomplished for a range of brightness of the host star. {\bf We can expect more transiting planets to be discovered in the coming years in the $V$ = 8 to 12 range and these DD observations, with no proprietary time as usual, will be of major influence in guiding future observations by the community.} Each visit will start with a broadband filter observation of about 1 second (F555W) to define the wavelength scale; the grism observations will be taken with autoimages suppressed. These observations closely follow the successful GO/DD-10441 study of TrES-1 with ACS/HRC and the grism. The stars differ by only half a magnitude (XO-1b brighter), allowing great confidence in the technical approach. Visits 1 and 2 (ACS) were withdrawn following instrument failure and have been replaced with Visits 33 and 34 (NICMOS). The NICMOS observations adopt the defocus used previously in GO-9832, but via the newly preferred style not requiring special commanding that is used in GO-11335. IMPLEMENTATION NOTES: the new parameter CAMERA-FOCUS=DEFOCUS and aperture NIC3-FIXD is used to place NIC3 focus mechanism at -0.5 mm and adjust the target placement in the aperture for the defocus respectively. Review of all potential scheduling windows has resulted in selection of two at 2008:040:21 and 2008:052:16 that yield best phase coverage of the transit event. The Phase II for visits 033 and 034 will contain BETWEENs restricting to these dates respectively, in the event that one or both of these opportunities cannot be used these would need modification. The two visits above should be conidered and "all or none", if either needs to be changed, then we'll want the option to select both visits. Spacing of 12 days between visits yields optimal phase coverage. COOL STARS 0 false 0.0 false false false false false false RESTRICTED STAR EXTRA-SOLAR PLANET G V-IV The parallax is unknown - an approximate value for its distance is 200 pc. B-V = 0.66 XO-1 J2000 16 02 11.8400 +28 10 10.40 J2000 CALIBRATION ASTROMETRIC Fpg=12.0, Jpg=13.6, Npg=11.75 N64U000307 J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC Fpg=14.0, Jpg=16.0, Npg = 13.5 N64U000306 J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC Fpg=13.6, Jpg=14.7, Npg=13.3 N64000520 J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC seleted from DSS plate Fpg=15.7, Jpg=16.5, Npg=15.7 N64U022297 J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC selected from DSS plate Fpg=15.7, Jpg=17.46. Npg=15.32 N64U022291 J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC selected from DSS plate Fpg=16.03, Jpg=16.74, Npg=16.0 N64U022116 J2000 00 00 0.0000 +00 00 0.00 J2000 ACS/HRC Spectroscopic No No G800L FGS POS No F583W (Tic-Visit :proposal-id 10998 :visit-id "01" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 15:29:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 502832 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2615 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "01" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2660 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "01" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2660 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "01" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2660 :al-overhead-at-end 0 :internal-dur-at-end 266 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) false 4 0 For HST observations of any two transits separated by three orbital periods of XO-1 (~12 days), the earth-occultation gaps of the first visit are filled in by the second visit. More generally, for N transits separating the two visits, we require that N modulo 6 = 3, so N = 3, 9, 15, ... satisfy our needs. We require out-of-transit observations made at the beginning and end of each visit. This means that the first exposure of a visit must have phase < 0.98 and the last exposure of that visit must have phase > 0.02. The following was written in May of 2006 as a guide to illustrate the above generic requirement. Below is a table of pairs of dates (5/24 = May 24) that we believe meet the above requirement. Visit1 Visit2 comment 5/24 6/05 5/24 6/28 X 5/28 6/09 5/28 7/02 X 6/01 6/13 X 6/01 7/06 X 6/05 6/17 X 6/05 7/10 X 6/09 6/21 X 6/09 7/14 X in the comment field means that we believe the 2nd visit is not allowed in 2-gyro mode (according to our running of APT) but maybe more sophisticated scheduling software will find they are possible. Likewise we believe HST cannot observe this target after 7/18 until 2007. (Tic-Visit :proposal-id 10998 :visit-id "02" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 15:29:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 502832 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2650 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "02" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2660 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "02" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2660 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "02" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2660 :al-overhead-at-end 0 :internal-dur-at-end 266 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) false 4 0 For HST observations of any two transits separated by three orbital periods of XO-1 (~12 days), the earth-occultation gaps of the first visit are filled in by the second visit. More generally, for N transits separating the two visits, we require that N modulo 6 = 3, so N = 3, 9, 15, ... satisfy our needs. Below is a table of pairs of dates (5/24 = May 24) that we believe meet the above requirement. Visit1 Visit2 comment 5/24 6/05 5/24 6/28 X 5/28 6/09 5/28 7/02 X 6/01 6/13 X 6/01 7/06 X 6/05 6/17 X 6/05 7/10 X 6/09 6/21 X 6/09 7/14 X in the comment field means that we believe the 2nd visit is not allowed in 2-gyro mode (according to our running of APT) but maybe more sophisticated scheduling software will find they are possible. Likewise we believe HST cannot observe this target after 7/18 until 2007. We require out-of-transit observations made at the beginning and end of each visit. This means that the first exposure of a visit must have phase < 0.98 and the last exposure of that visit must have phase > 0.02. (Tic-Visit :proposal-id 10998 :visit-id "11" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 16:15:08.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "11" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2793 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10998 :visit-id "12" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 16:15:14.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "12" :obset-id "12" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "12" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10998 :visit-id "21" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 15:30:05.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "21" :obset-id "21" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "21" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10998 :visit-id "22" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 15:30:10.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "22" :obset-id "22" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "22" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10998 :visit-id "31" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 15:30:15.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "31" :obset-id "31" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "31" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10998 :visit-id "32" :proposal-version -1 :trans-version "20060619" :date "27-Oct-2006 15:30:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "32" :obset-id "32" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "32" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0 This visit replaces original V01 -- withdrawn ACS/HRC. Uses one extra orbit for total of five per award in the ACS to other instruments switchover award. (Tic-Visit :proposal-id 10998 :visit-id "33" :proposal-version -1 :trans-version "20070709" :date "03-Dec-2007 15:39:12.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 3394448 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "33" :obset-id "33" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "33" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2737 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "33" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "33" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "33" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "33" :orbit-number 5 :pcs-time 355 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 109 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 5 0 Direct image through narrow-band filter used to establish wavelengths of grism exposures. NSAMP=7 without defocus should just hit saturation, with defocus should be factor of a few below and okay. The POS TARGs used throughout are intended to place the first order spectrum over x = 86-197, y=63, i.e. on a very clean position in terms of flat field deviations and bad pixels. This is similar to position used previously for HD 209458 observations with a minor tweak. Expected exposure levels are about half of full well depth in center of spectra. During first orbit we take two alternating sequences with standard 40s exposures, and 32s exposures. Comparing these will allow verification that count level nonlinearity has been properly dealt with. From here until end of program are identical time series observations of 40 second exposures. This visit replaces original V02 -- withdrawn ACS/HRC. Uses one extra orbit for total of five per award in the ACS to other instruments switchover award. (Tic-Visit :proposal-id 10998 :visit-id "34" :proposal-version -1 :trans-version "20070709" :date "30-Nov-2007 16:01:00.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 3382304 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10998 :visit-id "34" :obset-id "34" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10998 :visit-id "34" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "34" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "34" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "34" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2776 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10998 :visit-id "34" :orbit-number 5 :pcs-time 355 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 109 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 5 0 Direct image through narrow-band filter used to establish wavelengths of grism exposures. NSAMP=7 without defocus should just hit saturation, with defocus should be factor of a few below and okay. During first orbit we take two alternating sequences with standard 40s exposures, and 32s exposures. Comparing these will allow verification that count level nonlinearity has been properly dealt with. From here until end of program are identical time series observations of 40 second exposures.