Observational Constraints

The mechanism for incorporating observational constraints into the vespa calculations is via the Constraint object. The way this is currently implemented is that a Constraint is essentially a boolean array of the same length as a EclipsePopulation (or StarPopulation, more generally), where simulated instances that would not have been detected by the observation in question remain True, and any instances that would have been observed become False.

Contrast Curve Constraint

One of the most common kinds of follow-up observation for false positive identification/ analysis is a high-resolution imaging observation. The output of such an observation is a “contrast curve”: the detectable brightness contrast as a function of angular separation from the central source. As every false positive EclipsePopulation simulation includes simulated magnitudes in many different bands as well as simulated sky-positions relative to the central target star, it is very easy to implement a contrast curve in this way: any instances that would have been detected by the observation get ruled out, and thus the “prior” factor diminishes for that scenario (this is kept track of by the EclipsePopulation.countok attribute).

class vespa.stars.contrastcurve.ContrastCurve(rs, dmags, band, mag=None, name=None)[source]

Object representing an imaging contrast curve

Usually accessed via ContrastCurveFromFile and then applied using ContrastCurveConstraint, e.g., through StarPopulation.apply_cc().

Parameters:
  • rs – Angular separation from target star, in arcsec.
  • dmags – Magnitude contrast.
  • band – Photometric bandpass in which observation is taken.
  • mag – Magnitude of central star (rarely used?)
  • name – Name; e.g., “PHARO J-band”, “Keck AO”, etc. Should be a decent label.
class vespa.stars.contrastcurve.ContrastCurveFromFile(filename, band, mag=None, mas=False, **kwargs)[source]

A contrast curve derived from a two-column file

Parameters:
  • filename – Filename of contrast curve; first column separation in arcsec, second column delta-mag.
  • band – Bandpass of imaging observation.
  • mas – Set to True if separation is in milliarcsec rather than arcsec.
class vespa.stars.contrastcurve.ContrastCurveConstraint(rs, dmags, cc, name='CC', **kwargs)[source]