WFC3 SOC, October 04, 2007

WFC3 GrismsResults from TV2

2D Simulations

Harald Kuntschner, Jeremy Walsh, Martin Kümmel

ST-ECF

WFC3 SOC, October 04, 2007

Overview

WFC3 SOC, October 04, 2007

WFC3-IR G102

directimage

0th order 1st order 2nd order

1014 pixel (full size)

detector defectsCombined white light + direct image

WFC3 SOC, October 04, 2007

WFC3-IR G141

directimage

0th order 1st order 2nd order

1014 pixel (full size)

detector defects

3rd order

Combined white light + direct image

WFC3 SOC, October 04, 2007

WFC3-UV G280

Direct image

0th order

1st order -1st order

4096 pixel (full size)

Combined white light + direct image

WFC3 SOC, October 04, 2007

WFC3-UV G280

0th order

+1st -1st

4096 pixel (full size)

+2st -2st

Combined monochromatorsteps

WFC3 SOC, October 04, 2007

WFC3-UV G280

+1+2

• +8 to -8 orders visible

• Heavy order overlap for > +2 order

• Order overlap in y-direction between +1st and +2nd beyond ~380nm

+3+4

+5

+8

+7+6

0-1

-2-3

-4

-5-6

-7

-8

WFC3 SOC, October 04, 2007

WFC3-IR G102 Throughput

• 1st order– Peak efficiency of ~30%

at 960 - 1120nm– Good sensitivity range:

840 - 1140nm

• 2nd order– Efficiency < 5%

• 0th order– Efficiency < 1.5%

WFC3 SOC, October 04, 2007

WFC3-IR G102 aperture corrections

• Aperture corrections are largely wavelength independent

• 95% flux within ~10 pixel aperture

WFC3 SOC, October 04, 2007

WFC3-IR G141 Throughput

• 1st order– Peak efficiency of ~40%

at 1420 - 1640nm– Good sensitivity range:

1120 - 1660nm

• 2nd order– Efficiency < 6%

• 0th order– Efficiency < 1.5%

WFC3 SOC, October 04, 2007

WFC3-IR G141 aperture corrections

• Aperture corrections are largely wavelength independent

• 95% flux within ~12 pixel aperture

WFC3 SOC, October 04, 2007

WFC3-UV G280 Throughput

• 1st order– Peak efficiency of 24%

at 240nm– Good sensitivity range:

200 - 330nm

• 2nd order– Efficiency < 2%

• 0th order– Efficiency equal to first

order at 330nm and rising!

WFC3 SOC, October 04, 2007

WFC3-UV G280 Throughput

• Higher order efficiencies are at the ~0.1% level

WFC3 SOC, October 04, 2007

WFC3-IR G141 trace

• Linear trace solutions with rms < 0.05 pixel

• f(X-Xref) = 0.0074 * (X-Xref) + 1.1

WFC3 SOC, October 04, 2007

WFC3-IR G1412-dim trace solution

central trace:

f(X-Xref) = 0.0074 * (X-Xref) + 1.1

Offset = f(X,Y)

rms < 0.2 pixel

Slope = f(X,Y)

WFC3 SOC, October 04, 2007

WFC3-IR G141 dispersion

• Linear dispersion solutions with rms < 1 Å

• f(X) [Å] = 46.9 * (X) + 8950

* Data points omitted in fit due to wavelength shift caused by steep sensitivity decline

WFC3 SOC, October 04, 2007

WFC3-IR G1412-dim dispersion solution

central dispersion solution:

f(X’) [Å] = 46.9 * (X’) + 8950

Offset = f(X,Y) units=Å

rms < 0.1 pixel

Dispersion = f(X,Y) units=Å

WFC3 SOC, October 04, 2007

WFC3-IR G1022-dim disp solution

central dispersion solution:

f(X) [Å] = 24.6 * (X) + 6376

Offset = f(X’,Y’) units=Å

rms < 0.1 pixel

Dispersion = f(X’,Y’) units=Å

WFC3 SOC, October 04, 2007

WFC3-IR PSF

Gaussian FWHM = 2.3 pixelMoffat FWHM = 1.9 pixel; beta=1.08

Gaussian FWHM = 2.7 pixelMoffat FWHM = 2.3 pixel; beta=1.14

Moffat

Gaussian

WFC3 SOC, October 04, 2007

WFC3-UV PSF

Gaussian FWHM = 3.4 pixelMoffat FWHM = 2.9 pixel; beta=1.4

Gaussian FWHM = 3.8 pixelMoffat FWHM = 3.3 pixel; beta=1.5

Moffat

Gaussian

230-260 nm 300-400 nm

WFC3 SOC, October 04, 2007

WFC3-UV G280 Trace

+2 order +1 order -1 order

5th order polynomial fits

200nm

530nm

200nm

200nm 530nm530nm

WFC3 SOC, October 04, 2007

WFC3-UV G280 dispersion

+1 order• 1st order polynomial

fit to visualize the dispersion function

• 4th order polynomial needed to achieve good fit (rms ~ 0.15 pixel)

• ~13 Å per pixel