AnalyticPhotometryModel¶

class lsst.validate.drp.matchreduce.AnalyticPhotometryModel(matchedMultiVisitDataset, brightSnr=100, medianRef=100, matchRef=500)[source]¶

Bases: lsst.validate.drp.base.BlobBase

Serializable analytic photometry error model for multi-visit catalogs.

This model is originally presented in http://arxiv.org/abs/0805.2366v4 (Eq 4, 5):

\[\sigma_1^2 &= \sigma_\mathrm{sys}^2 + \sigma_\mathrm{rand}^2 \ x &= 10^{0.4(m-m_5)} \ \sigma_\mathrm{rand}^2 &= (0.04 - \gamma) x + \gamma x^2~[\mathrm{mag}^2]\]

Parameters:	matchedMultiVisitDataset : MatchedMultiVisitDataset A dataset containing matched statistics for stars across multiple visits. brightSnr : float, optional Minimum SNR for a star to be considered “bright”. medianRef : float, optional Median reference astrometric scatter in millimagnitudes matchRef : int, optional Should match at least matchRef stars.

Notes

The scatter and match defaults are appropriate to SDSS are stored here. For SDSS, stars with mag < 19.5 should be completely well measured. This limit is a band-dependent statement most appropriate to r.

Attributes

brightSnr	(float) Threshold in SNR for bright sources used in this model.
sigmaSys	(float) Systematic error floor.
gamma	(float) Proxy for sky brightness and read noise.
m5	(float) 5-sigma photometric depth (magnitudes).
photRms	(float) RMS photometric scatter for ‘good’ stars (millimagnitudes).