from __future__ import print_function, division
import numpy as np
from .baseObs import BaseObs
__all__ = ['DirectObs']
[docs]class DirectObs(BaseObs):
"""
Generate observations of a set of moving objects: exact ephemeris at the times of each observation.
First generates observations on a rough grid and looks for observations within a specified tolerance
of the actual observations; for the observations which pass this cut, generates a precise ephemeris
and checks if the object is within the FOV.
Parameters
----------
footPrint: str, opt
Specify the footprint for the FOV. Options include "camera", "circle", "rectangle".
'Camera' means use the actual LSST camera footprint (following a rough cut with a circular FOV).
Default is circular FOV.
rFov : float, opt
If footprint is "circular", this is the radius of the fov (in degrees).
Default 1.75 degrees.
xTol : float, opt
If footprint is "rectangular", this is half of the width of the (on-sky) fov in the RA
direction (in degrees).
Default 5 degrees. (so size of footprint in degrees will be 10 degrees in the RA direction).
yTol : float, opt
If footprint is "rectangular", this is half of the width of the fov in Declination (in degrees).
Default is 3 degrees (so size of footprint in degrees will be 6 degrees in the Dec direction).
ephMode: str, opt
Mode for ephemeris generation - nbody or 2body. Default is nbody.
prelimEphMode: str, opt
Mode for preliminary ephemeris generation, if any is done. Default is 2body.
ephType: str, opt
Type of ephemerides to generate - full or basic.
Full includes all values calculated by openorb; Basic includes a more basic set.
Default is Basic. (this includes enough information for most standard MAF metrics).
ephFile: str or None, opt
The name of the planetary ephemerides file to use for ephemeris generation.
Default (None) will use the default for PyOrbEphemerides.
obsCode: str, opt
Observatory code for ephemeris generation. Default is "I11" - Cerro Pachon.
obsTimeCol: str, opt
Name of the time column in the obsData. Default 'observationStartMJD'.
obsTimeScale: str, opt
Type of timescale for MJD (TAI or UTC currently). Default TAI.
seeingCol: str, opt
Name of the seeing column in the obsData. Default 'seeingFwhmGeom'.
This should be the geometric/physical seeing as it is used for the trailing loss calculation.
visitExpTimeCol: str, opt
Name of the visit exposure time column in the obsData. Default 'visitExposureTime'.
obsRA: str, opt
Name of the RA column in the obsData. Default 'fieldRA'.
obsDec: str, opt
Name of the Dec column in the obsData. Default 'fieldDec'.
obsRotSkyPos: str, opt
Name of the Rotator column in the obsData. Default 'rotSkyPos'.
obsDegrees: bool, opt
Whether the observational data is in degrees or radians. Default True (degrees).
outfileName : str, opt
The output file name.
Default is 'lsst_obs.dat'.
obsMetadata : str, opt
A string that captures provenance information about the observations.
For example: 'kraken_2026, MJD 59853-61677' or 'baseline2018a minus NES'
Default ''.
tstep: float, opt
The time between initial (rough) ephemeris generation points, in days.
Default 1 day.
roughTol: float, opt
The initial rough tolerance value for positions, used as a first cut to identify potential
observations (in degrees).
Default 10 degrees.
"""
def __init__(self, footprint='circular', rFov=1.75, xTol=5, yTol=3,
ephMode='nbody', prelimEphMode='2body', ephType='basic', obsCode='I11',
ephFile=None,
obsTimeCol='observationStartMJD', obsTimeScale='TAI',
seeingCol='seeingFwhmGeom', visitExpTimeCol='visitExposureTime',
obsRA='fieldRA', obsDec='fieldDec', obsRotSkyPos='rotSkyPos', obsDegrees=True,
outfileName='lsst_obs.dat', obsMetadata='', tstep=1.0, roughTol=10.0):
super().__init__(footprint=footprint, rFov=rFov, xTol=xTol, yTol=yTol,
ephMode=ephMode, ephType=ephType, obsCode=obsCode,
ephFile=ephFile, obsTimeCol=obsTimeCol, obsTimeScale=obsTimeScale,
seeingCol=seeingCol, visitExpTimeCol=visitExpTimeCol,
obsRA=obsRA, obsDec=obsDec, obsRotSkyPos=obsRotSkyPos, obsDegrees=obsDegrees,
outfileName=outfileName, obsMetadata=obsMetadata)
self.tstep = tstep
self.roughTol = roughTol
if prelimEphMode not in ('2body', 'nbody'):
raise ValueError('Ephemeris generation must be 2body or nbody.')
self.prelimEphMode = prelimEphMode
def _headerMeta(self):
# Specific header information for direct obs.
self.outfile.write('# direct obs header metadata\n')
self.outfile.write('# observation generation via %s\n' % self.__class__.__name__)
self.outfile.write('# ephMode %s prelimEphMode %s\n' % (self.ephMode, self.prelimEphMode))
self.outfile.write('# rough tolerance for preliminary match %f\n' % self.roughTol)
self.outfile.write('# time step for preliminary match %f\n' % self.tstep)
[docs] def run(self, orbits, obsData):
"""Find and write the observations of each object to disk.
For each object, generate a very rough grid of ephemeris points (typically using 2body integration).
Then identify pointings in obsData which are within
Parameters
----------
orbits: lsst.sims.movingObjects.Orbits
The orbits to generate ephemerides for.
obsData : np.recarray
The simulated pointing history data.
"""
# Set the times for the rough ephemeris grid.
timeStep = float(self.tstep)
timeStart = obsData[self.obsTimeCol].min() - timeStep
timeEnd = obsData[self.obsTimeCol].max() + timeStep
rough_times = np.arange(timeStart, timeEnd + timeStep / 2.0, timeStep)
print('Generating preliminary ephemerides on a grid of %f day timesteps.' % (timeStep))
# For each object, identify observations where the object is within the FOV (or camera footprint).
for sso in orbits:
objid = sso.orbits['objId'].iloc[0]
sedname = sso.orbits['sed_filename'].iloc[0]
# Generate ephemerides on the rough grid.
ephs = self.generateEphemerides(sso, rough_times,
ephMode=self.prelimEphMode, ephType=self.ephType)[0]
# Find observations which come within roughTol of the fov.
ephsIdxs = np.searchsorted(ephs['time'], obsData[self.obsTimeCol])
roughIdxObs = self._ssoInCircleFov(ephs[ephsIdxs], obsData, self.roughTol)
if len(roughIdxObs) > 0:
# Generate exact ephemerides for these times.
times = obsData[self.obsTimeCol][roughIdxObs]
ephs = self.generateEphemerides(sso, times, ephMode=self.ephMode, ephType=self.ephType)[0]
# Identify the objects which fell within the specific footprint.
idxObs = self.ssoInFov(ephs, obsData[roughIdxObs])
# Write these observations to disk.
self.writeObs(objid, ephs[idxObs], obsData[roughIdxObs][idxObs], sedname=sedname)