The ESA astrometric space mission, Gaia, is poised to measure parallaxes of a billion Milky Way stars, revolutionizing our knowledge of the luminosity and distance scales of every stellar type. Twenty-five of these billion sources are invaluable; nearby, long period classical Cepheids whose 1% to 3% parallax measurements from Gaia can solidify the distance scale beyond the Milky Way and the Hubble constant to better than 1% precision. The missing component to achieving this goal is a precise photometric cross-calibration between these bright Milky Way Cepheids with 4<m(H)<8 and those observed with HST in galaxies at distances of tens of megaparsecs. While temporal variations in the ground-based near-IR system due to atmospheric water and OH prohibit such precise cross-calibration between the ground and HST photometric systems, it can now be done directly with HST. We propose to observe 25 of the nearest Milky Way Cepheids with WFC3 using modes recently devised to accomodate very bright targets such as Vega. Our goal is to retain and transfer the precision of the distance scale measured with Gaia to distances only measurable by HST. Undertaking this calibration now will secure this invaluable enhancement to HST|*|s enormous archive of over a thousand orbits of data on the distance scale, open a new path for the scientific use of these modes by future GOs and inform planning of their future use with JWST. TBD COSMOLOGY 0 false false 0.0 0.0 false false false AVAILABLE STAR CEPHEID This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 STAR CEPHEID This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W WFC3/IR Spectroscopic No No G141 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1316040553000 280.0 (Tic-Visit :proposal-id 12679 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "30-Jul-2012 08:41:04.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1832992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3152 :al-overhead-at-end 40 :internal-dur-at-end 683 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3600.0 :pcs-gap 0 ) true 1 0 1. IR: Shortest narrow-band direct image to identify Cepheid for subsequent grism. F167N, IRSUB64 (64x64 subarray) RAPID NSAMP=2 (unsaturated in first samp for H>5, 2/3 Cepheids, could be used with Cepheid stellar type to get F160W mag), could do 2 dithers. Dither small integer 1,1, to allow easy combination in pixel space 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 4. IR: Full frame F160W to get photometry of fainter background stars, RAPID, NSAMP=5,unsaturated photometry for stars H>12.5, need to check if there are some of these. Otherwise this won’t help (could use subarray if there are some at H>10). 2 dithers not critical since this is a statistical measure and I can tolerate a bad pix 4. IR: Full frame F160W to get photometry of fainter background stars, RAPID, NSAMP=5,unsaturated photometry for stars H>12.5, need to check if there are some of these. Otherwise this won’t help (could use subarray if there are some at H>10). 2 dithers not critical since this is a statistical measure and I can tolerate a bad pix 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. 5. IR: Full frame, G141, spatial scan at FGS 1”/sec rate, RAPID, NSAMP=10 to 15, same pos targ as #3, goal to get -1 and +1 orders of Ceph, excellent S/N. This is not so critical for Cepheids with H>5 since already got this in #2, but its important for brighter Cepheids. The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1315861969000 278.0 (Tic-Visit :proposal-id 12679 :visit-id "02" :proposal-version -1 :trans-version "20110811" :date "13-Sep-2011 15:38:25.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1832992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3218 :al-overhead-at-end 0 :internal-dur-at-end 685 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3600.0 :pcs-gap 0 ) false 1 0 1. IR: Shortest narrow-band direct image to identify Cepheid for subsequent grism. F167N, IRSUB64 (64x64 subarray) RAPID NSAMP=2 (unsaturated in first samp for H>5, 2/3 Cepheids, could be used with Cepheid stellar type to get F160W mag), could do 2 dithers. Dither small integer 1,1, to allow easy combination in pixel space 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 4. IR: Full frame F160W to get photometry of fainter background stars, RAPID, NSAMP=5,unsaturated photometry for stars H>12.5, need to check if there are some of these. Otherwise this won’t help (could use subarray if there are some at H>10). 2 dithers not critical since this is a statistical measure and I can tolerate a bad pix 4. IR: Full frame F160W to get photometry of fainter background stars, RAPID, NSAMP=5,unsaturated photometry for stars H>12.5, need to check if there are some of these. Otherwise this won’t help (could use subarray if there are some at H>10). 2 dithers not critical since this is a statistical measure and I can tolerate a bad pix 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. 5. IR: Full frame, G141, spatial scan at FGS 1”/sec rate, RAPID, NSAMP=10 to 15, same pos targ as #3, goal to get -1 and +1 orders of Ceph, excellent S/N. This is not so critical for Cepheids with H>5 since already got this in #2, but its important for brighter Cepheids. The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317076007000 274.0 (Tic-Visit :proposal-id 12679 :visit-id "22" :proposal-version -1 :trans-version "20110509" :date "15-Sep-2011 09:28:41.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1522880 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "22" :obset-id "22" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "22" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2716 :al-overhead-at-end 0 :internal-dur-at-end 680 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3301 :pcs-gap 0 ) true 1 0 1. IR: Shortest narrow-band direct image to identify Cepheid for subsequent grism. F167N, IRSUB64 (64x64 subarray) RAPID NSAMP=2 (unsaturated in first samp for H>5, 2/3 Cepheids, could be used with Cepheid stellar type to get F160W mag), could do 2 dithers. Dither small integer 1,1, to allow easy combination in pixel space 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. Disable take data flag before UVIS FGS spatial scans Enable take data flag after UVIS FGS spatial scans The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1317070319000 275.0 (Tic-Visit :proposal-id 12679 :visit-id "21" :proposal-version -1 :trans-version "20120604" :date "30-Jul-2012 08:40:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1522880 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "21" :obset-id "21" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "21" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2669 :al-overhead-at-end 40 :internal-dur-at-end 678 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3333 :pcs-gap 0 ) true 1 0 1. IR: Shortest narrow-band direct image to identify Cepheid for subsequent grism. F167N, IRSUB64 (64x64 subarray) RAPID NSAMP=2 (unsaturated in first samp for H>5, 2/3 Cepheids, could be used with Cepheid stellar type to get F160W mag), could do 2 dithers. Dither small integer 1,1, to allow easy combination in pixel space 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. Disable take data flag before UVIS FGS spatial scans Enable take data flag after UVIS FGS spatial scans The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1330774157000 94.0 (Tic-Visit :proposal-id 12679 :visit-id "23" :proposal-version -1 :trans-version "20111111" :date "25-Jan-2012 07:35:53.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1602112 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "23" :obset-id "23" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "23" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2908 :al-overhead-at-end 0 :internal-dur-at-end 678 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3301 :pcs-gap 0 ) true 1 0 1. IR: Shortest narrow-band direct image to identify Cepheid for subsequent grism. F167N, IRSUB64 (64x64 subarray) RAPID NSAMP=2 (unsaturated in first samp for H>5, 2/3 Cepheids, could be used with Cepheid stellar type to get F160W mag), could do 2 dithers. Dither small integer 1,1, to allow easy combination in pixel space 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. 1330699925000 95.0 (Tic-Visit :proposal-id 12679 :visit-id "24" :proposal-version -1 :trans-version "20111111" :date "25-Jan-2012 07:36:04.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1602112 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "24" :obset-id "24" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "24" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2908 :al-overhead-at-end 0 :internal-dur-at-end 678 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) true 1 0 1. IR: Shortest narrow-band direct image to identify Cepheid for subsequent grism. F167N, IRSUB64 (64x64 subarray) RAPID NSAMP=2 (unsaturated in first samp for H>5, 2/3 Cepheids, could be used with Cepheid stellar type to get F160W mag), could do 2 dithers. Dither small integer 1,1, to allow easy combination in pixel space 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 2. IR: Shortest 256x256 G141 grism of Cepheid, GRISM256 gets first order, RAPID, NSAMP=2, unsaturated in first samp for H>5.5, gets 2/3 Cepheids spectrophotometry for F160W, should do 2 dithers. There will be persistence at x=522,y=522 and spectrum at y=532 so need a POS TARG of delta y = - 50 pixels = -6.055” to move target up and away from persistence 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. 3. IR: Full Frame G141 grism to get -1 order of Cepheid, GRSIM1024, RAPID, NSAMP= 4, puts reference at 497,562, need to move pos targ x=+200 pix or +27.1” to center on zeroeth order and fit -1 order in frame, do 2 dithers. Gets -1 order spectrophotometry for all Cepheids (H>3, so can do a few reads, may be more a buffer issue). Persistence in center of frame so won’t touch -1 order. This frame also gets +1 order for fainter background stars to cross-calibrate to their F160W in next frame. The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. Please note critical scheduling window, Sept 10-18 1347821596000 275.0 (Tic-Visit :proposal-id 12679 :visit-id "25" :proposal-version -1 :trans-version "20120802" :date "20-Nov-2012 16:40:47.0" :trans-errors '(:WARNINGS 5 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1417488 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "25" :obset-id "25" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "25" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2860 :al-overhead-at-end 0 :internal-dur-at-end 526 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3333 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. Please note critical scheduling window, March (Tic-Visit :proposal-id 12679 :visit-id "26" :proposal-version -1 :trans-version "20120802" :date "21-Nov-2012 16:27:05.0" :trans-errors '(:WARNINGS 7 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1358416 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12679 :visit-id "26" :obset-id "26" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12679 :visit-id "26" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2831 :al-overhead-at-end 0 :internal-dur-at-end 462 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3333 :pcs-gap 0 ) false 1 0