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Contamination
Background Subtraction
HST ACS sky background
ACS uses the original aXe implementation of 'Master sky image' (global background) and local background subtraction approach.
Basic method is outlined in aXe paper at
https://iopscience.iop.org/article/10.1086/596715/pdf (section 2.6)
HST WFC3 sky background
Master sky images have been provided for both G102 and G141, however the single images used by aXe do not take into account the full complexity of the sky background of grism observations. A more accurate background subtraction can be achieved by using separate images for each of the background components: zodiacal light, He I emission and scattered light (for G141).
More info at
https://www.stsci.edu/hst/instrumentation/wfc3/documentation/grism-resources/ir-grism-master-sky-images
Relevant paper
https://iopscience.iop.org/article/10.3847/1538-4357/aa81cc/pdf (section 3.2.6)
Most recent 'WFC3_Back' (Nor's slides)
Flatfielding
1D Spectral Extraction
1-D extraction
non-weighted extraction (section 3.3.2, figure 11)
https://iopscience.iop.org/article/10.3847/1538-4357/aa81cc/pdf
and
optimal extraction (section 3.3.2, figure 12)
https://iopscience.iop.org/article/10.3847/1538-4357/aa81cc/pdf
- original concept from Horne 1986
https://ui.adsabs.harvard.edu/abs/1986PASP...98..609H/abstract
2D Spectral Extraction
2-D extraction
Simulation based extraction (SBE) details in section 3.2.4 (figure 10)
https://iopscience.iop.org/article/10.3847/1538-4357/aa81cc/pdf
1D Forward modeling
2D Forward modeling
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