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Type:
Task
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Status: Done (View Workflow)
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Priority:
Normal
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Resolution: Done
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Affects Version/s: None
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Fix Version/s: None
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Component/s: None
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Labels:
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Epic Link:
During the work of PIPE2D-1582, we realized that getting Gaia fluxes from PFS spectra is tricky because the Gaia filter responses extend to <380nm, where PFS does not cover. There are multiple ways to deal with this, but this ticket is going to explore a simple but physically motivated way to infer the Gaia fluxes from PFS instead of a simple extrapolation of PFS spectra.
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Using the Pickles stellar library and limiting the stellar type to A-G stars, I got this figure. As expected, the Gaia G-band response at <380nm only has a small effect and the magnitude difference in the truncated G-band filter is only 0.017mag. The scatter is small; 0.003mag. In practice, the scatter will be even smaller because we limit the FLUXSTD spectral types to a narrower range (i.e., we use late-A to early-G only). So, I think we can safely use G = G_truncated + 0.017 for FLUXSTDs.
As for Bp, the effect is larger; the median magnitude difference is 0.1mag. However, the scatter is still only ~1%. I could fit polynomials to the points here, but I am not sure if that is needed. Maybe the simplest solution is just to do Bp = Bp_truncated + 0.101.
OK, I fitted polynomials just in case they are useful.
The filter responses to be assumed here are Gaia G and Bp, and their responses truncated at 380nm, where the PFS coverage ends. See the plot here.