sorcha.modules.PPTrailingLoss

Functions

calcTrailingLoss(dRaCosDec, dDec, seeing[, texp, ...])

Find the trailing loss from trailing and detection (Veres & Chesley 2017)

PPTrailingLoss(eph_df[, model, dra_cosdec_name, ...])

Calculates detection trailing losses. Wrapper for calcTrailingLoss.

Module Contents

calcTrailingLoss(dRaCosDec, dDec, seeing, texp=30.0, model='circularPSF', a_trail=0.761, b_trail=1.162, a_det=0.42, b_det=0.003)[source]

Find the trailing loss from trailing and detection (Veres & Chesley 2017)

Parameters:

  • dRa (float or array of floats) -- on sky velocity component in RA*Cos(Dec). [Units: deg/day]

  • dDec (float/array of floats) -- on sky velocity component in Dec. [Units: deg/day]

  • seeing (float or array of floats) -- FWHM of the seeing disk. [Units: arcseconds]

  • texp (float or array of floats, default=30) -- Exposure length. [Units: seconds]

  • model (string, optional, default="circularPSF") -- Options: 'circularPSF' or trailedSource' 'circularPSF': Trailing loss due to the DM detection algorithm. Limit SNR: 5 sigma in a PSF-convolved image with a circular PSF (no trail fitting). Peak fluxes will be lower due to motion of the object. 'trailedSource': Unavoidable trailing loss due to spreading the PSF over more pixels lowering the SNR in each pixel. See https://github.com/rhiannonlynne/318-proceedings/blob/master/Trailing%20Losses.ipynb for details.

  • a_trail (float, default=0.761) -- a fit parameters for trailedSource model. Default parameters from Veres & Chesley (2017).

  • b_trail (float, default=1.162) -- b fit parameters for trailedSource model. Default parameters from Veres & Chesley (2017).

  • a_det (float, default=0.420) -- a fit parameters for circularPSF model. Default parameters from Veres & Chesley (2017).

  • b_det (float, default=0.003) -- b fit parameters for circularPSF model. Default parameters from Veres & Chesley (2017).

Returns:

dmag -- Loss in detection magnitude due to trailing.

Return type:

float or array of floats

PPTrailingLoss(eph_df, model='circularPSF', dra_cosdec_name='RARateCosDec_deg_day', ddec_name='DecRate_deg_day', dec_name='Dec_deg', seeing_name_survey='seeingFwhmEff_arcsec', visit_time_name='visitExposureTime')[source]

Calculates detection trailing losses. Wrapper for calcTrailingLoss.

Parameters:

  • eph_df (pandas dataframe) -- Dataframe of observations for which to calculate trailing losses.

  • model (string, default="circularPSF") -- Photometric model. Either 'circularPSF' or 'trailedSource': see docstring for calcTrailingLoss for details.

  • dra_name (string, default="RARateCosDec_deg_day") -- "eph_df" column name for object RA rate. Assumes cos(dec) normalization has already been applied

  • ddec_name (string, default="DecRate_deg_day") -- "eph_df" column name for object dec rate.

  • dec_name (string, default="Dec_deg") -- "eph_df" column name for object declination.

  • seeing_name_survey (string, default="seeingFwhmEff_arcsec") -- "eph_df" column name for seeing.

  • visit_time_name (string, default="visitExposureTime") -- "eph_df" column name for exposure length.

Returns:

dmag -- Loss in detection magnitude due to trailing losses.

Return type:

float or array of floats

Notes

Assumes 'eph_df" has RA and Dec stored in deg/dayrates and the seeing in arcseconds