Calibration of the WFC3 Emission-Line Filters and Application of the Results to the Greatest Source of Uncertainties in Determining Abundances in Gaseous Nebulae

This WFC3 calibration proposal has been previewed with the WFC3 Team and the grouping with a science program approved by Brett Blacker. Assigned ID: 8 ----- Attempting Submission 1 (Tue Jan 26 21:28:15 GMT 2010) ----- HST Phase I Proposal 8 (Calibration.apt) successfully submitted. ----- Attempting Submission 2 (Wed Feb 17 14:59:20 GMT 2010) ----- added additional orient ranges per PI request ----- Attempting Submission 1 (Thu Jul 01 18:38:42 GMT 2010) ----- ----- Attempting Submission 2 (Mon Dec 20 20:31:12 GMT 2010) ----- Calibration of the WFC3 Emission-Line Filters and Application of the Results to the Greatest Source of Uncertainties in Determining Abundances in Gaseous Nebulae The WFC3 is arguably the most powerful camera that has been used on the HST. This capability arises in part from the uniquely complete set of narrow-band filters that were incorporated for making images of nebulae in emission-lines. Turning these oft-times beautiful images into scientifically useful information requires accurate flux calibration of the filters, which is the first subject of this proposal. The present plan is that WFC3 calibration will be done from pre-launch properties of the filters and observations of stars. The WFC3 filters transmission profiles were measured pre-launch in a different optical configuration and temperature than applies within the WFC3, thus rendering uncertain any flux calibrations tied to those pre-launch measurements. We propose to perform a “ground-truth” calibration of the WFC3 narrow-band filters using NGC 6720 as a reference source, in much the same manner that the PI did when calibrating similar filters in the WFPC2 and the ACS. These new calibrations will then be used to address the t^2 problem in Gaseous Nebulae. This is the source of uncertainties in the relative abundances of factors 1.1 to 10 and undermines efforts to trace the abundance variations within our Galaxy and other galaxies. The t^2 problem remains unresolved after four decades and the NGC 6720 images used for the filter calibration may resolve the problem if they show that regions of small-scale temperature fluctuations arise from low-temperature shadow-zones behind knots that are known to exist within the nebula or from high-temperature shocks that have been posited. Unlike the case of the Orion Nebula, where we have addressed this problem with fewer diagnostic filters, the geometry of NGC 6720 is ideally favorable for seeing these temperature variations and identifying their cause.

WFC3/UVIS imaging will be made of NGC 6720, the Ring Nebula. A set of full field images will be made centered on the central star and a set of quadrant filter images will be made in a portion of the nebula centered west of the central star. Coordinated parallel images will be made with the ACS. ISM AND CIRCUMSTELLAR MATTER 12 true 0.0 0.0 false false false false false false SUPPORTED ISM EMISSION LINE NEBULA PLANETARY NEBULA RING NEBULA 15.6 is for the central star, which is not important for this emission-line object. NGC6720STAR J2000 00 00 0.0000 +00 00 0.00 J2000 ISM EMISSION LINE NEBULA PLANETARY NEBULA RING NEBULA 15.6 is for the central star, which is not important for this emission-line object. SAMPLE-QUADS J2000 00 00 0.0000 +00 00 0.00 J2000 WFC3/UVIS Imaging No No FQ436N WFC3/UVIS Imaging No No FQ437N WFC3/UVIS Imaging No No FQ575N WFC3/UVIS Imaging No No FQ672N WFC3/UVIS Imaging No No FQ674N WFC3/UVIS Imaging No No FQ750N WFC3/UVIS Imaging No No F469N WFC3/UVIS Imaging No No F487N WFC3/UVIS Imaging No No F502N WFC3/UVIS Imaging No No F547M WFC3/UVIS Imaging No No F645N WFC3/UVIS Imaging No No F656N WFC3/UVIS Imaging No No F658N WFC3/UVIS Imaging No No F673N WFC3/UVIS Imaging No No F953N ACS/WFC Imaging No No F502N ACS/WFC Imaging No No F658N ACS/WFC Imaging No No F660N ACS/WFC Imaging No No F550M POS-TARG MOSAIC 3.264 LINE false false 2 63.697 WFC3-UVIS-MOSAIC-LINE 1

false

1277998573167 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. First Visit (Tic-Visit :proposal-id 12309 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "01-Jul-2010 10:36:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 8048736 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12309 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12309 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2938 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3030 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3042 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3039 :al-overhead-at-end 116 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "01" :orbit-number 5 :pcs-time 222 :si-vis-utilization 3045 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) false 5 0 1277998555050 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. Second Visit (Tic-Visit :proposal-id 12309 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "01-Jul-2010 10:35:53.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 6605024 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12309 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 12309 :visit-id "02" :obset-id "A2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12309 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2932 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3025 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "02" :orbit-number 3 :pcs-time 333 :si-vis-utilization 2940 :al-overhead-at-end 116 :internal-dur-at-end 354 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12309 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3050 :al-overhead-at-end 116 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) true 4 0