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 usingContrastCurveConstraint
, e.g., throughStarPopulation.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.