Synphot Data User's Guide

1.2 Future Instruments

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This section describes the keywords available for the science instruments planned for installation on HST during Servicing Mission 4: the Cosmic Origins Spectrograph (COS) and the Wide Field Camera 3 (WFC3). As of this writing (Jan. 2007), synphot support for these instruments is now (with preliminary values for the throughput tables) available.

1.2.1 COS

The COS keywords consist of a list of detectors, apertures, mirrors, gratings, and central wavelengths. FUV spectral simulations are performed by specifying one of the FUV gratings along with a central wavelength. NUV spectral simulations are performed by specifying one of the NUV gratings along with a central wavelength. Imaging simulations are performed by specifying one of the mirrors (mirrorb for bright objects) with the NUV detector.

In most cases, the synphot calculation includes all three stripes on the detector for a given observing mode. For the NUV G230L grating only, both first and second order light on stripe C are detectable. The second order bandpass overlaps the stripe A bandpass for some central wavelengths.

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Therefore, for G230L, separate keywords are used to designate stripes a, b, c1, and c2, where c1 and c2 refer to the first and second orders of stripe C, respectively. Consequently, it is necessary to perform the desired synphot calculation four times, changing the spectral element keyword in the obsmode each time, in order to obtain complete results for G230L simulations.

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Either the Primary Science Aperture (psa) or the Bright Object Aperture (boa) may be specified with any simulation; the Primary Science Aperture will be included by default if neither is specified.

Table 1.6: COS Keywords

Detectors	fuv nuv
Apertures	boa psa
Mirrors	mirrora mirrorb
FUV gratings	g130m g140l g160m
Central wavelengths for g130m	c1291 c1300 c1309 c1318 c1327
Central wavelengths for g140l	c1105 c1230
Central wavelengths for g160m	c1577 c1589 c1600 c1611 c1623
NUV gratings	g185m g225m g230la g230lb g230lc1 g230lc2 g285m
Central wavelengths for g185m	c1786 c1817 c1835 c1850 c1864 c1882 c1890 c1900 c1913 c1921 c1941 c1953 c1971 c1986 c2010
Central wavelengths for g225m	c2186 c2217 c2233 c2250 c2268 c2283 c2306 c2325 c2339 c2357 c2373 c2390 c2410
Central wavelengths for g230l	c2635 c2950 c3000 c3360
Central wavelengths for g285m	c2617 c2637 c2657 c2676 c2695 c2709 c2719 c2739 c2850 c2952 c2979 c2996 c3018 c3035 c3057 c3074 c3094

 

1.2.2 WFC3

The WFC3 keywords consist of a list of detectors, filters, and extraction apertures for each of its two channels.

The dn keyword is used to divide throughputs by the analog-to-digital converter (ADC) gain ratio, which transforms results from units of electrons to data numbers (DNs).

The qyc keyword is used to apply a wavelength-dependent quantum yield correction. For more detail, see Section 2.6, "Quantum Yield Correction (WFC3),".

The bkg keyword is used to perform an accurate background calculation for observing modes that use a grism. For more detail, see Section 2.7, "Background Calculation (WFC3)" .

The aper keyword is used to perform encircled energy calculations. For more detail, see Section 2.4, "Encircled energy (ACS, WFC3),".

Table 1.7: WFC3 Keywords

Detectors	uvis1 uvis2 ir
UVIS Filters	f200lp f218w f225w f275w f280n f300x f336w f343n f350lp f373n f390m f390w f395n f410m f438w f467m f469n f475w f475x f487n f502n f547m f555w f600lp f606w f621m f625w f631n f645n f656n f657n f658n f665n f673n f680n f689m f763m f775w f814w f845m f850lp f953n fq232n fq243n fq378n fq387n fq422m fq436n fq437n fq492n fq508n fq575n fq619n fq634n fq672n fq674n fq727n fq750n fq889n fq906n fq924n fq937n
UVIS Grism	g280
IR Filters	f098m f105w f110w f125w f126n f127m f128n f130n f132n f139m f140w f153m f160w f164n f167n
IR Grisms	g102 g141
Data numbers	dn
Quantum yield correction	qyc
Background calculation	bkg
Encircled energy radius values	aper#0.00 aper#0.10 aper#0.15 aper#0.20 aper#0.25 aper#0.30 aper#0.40 aper#0.50 aper#0.60 aper#0.80 aper#1.00 aper#1.50 aper#2.00