class rubin_sim.maf.metrics.HighVelocityNightsMetric(psf_factor=2.0, n_obs_per_night=2, snr_limit=None, velocity_col='velocity', **kwargs)

Bases: BaseMoMetric

Count the number of discovery opportunities (via trailing) for an SSobject.

Determine the first time an asteroid is observed is observed with a velocity high enough to make it appear trailed by a factor of psf_factor*PSF with n_obs_per_night observations within a given night.

psf_factor: float, optional

Object velocity (deg/day) must be >= 24 * psf_factor * seeingGeom (”) / visitExpTime (s). Default is 2 (i.e. object trailed over 2 psf’s).

n_obs_per_night: int, optional

Number of observations per night required. Default 2.

snr_limit: float or None

If snr_limit is set as a float, then requires object to be above snr_limit SNR in the image. If snr_limit is None, this uses the probabilistic ‘visibility’ calculated by the vis stacker, which means SNR ~ 5. Default is None.

velocity_col: str, optional

Name of the velocity column in the obs file. Default ‘velocity’. (note this is deg/day).


The time of the first detection where the conditions are satisifed.

Methods Summary

run(sso_obs, orb, hval)

Calculate the metric value.

Methods Documentation

run(sso_obs, orb, hval)

Calculate the metric value.

sso_obs: np.ndarray

The input data to the metric (same as the parent metric).

orb: np.ndarray

The information about the orbit for which the metric is being calculated.


The H value for which the metric is being calculated.

float or np.ndarray or dict