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# This file is currently part of obs_lsst but is written to allow it 

# to be migrated to the astro_metadata_translator package at a later date. 

# 

# This product includes software developed by the LSST Project 

# (http://www.lsst.org). 

# See the LICENSE file in this directory for details of code ownership. 

# 

# Use of this source code is governed by a 3-clause BSD-style 

# license that can be found in the LICENSE file. 

 

"""Metadata translation code for LSST simulations""" 

 

__all__ = ("LsstSimTranslator", ) 

 

import warnings 

import logging 

 

import astropy.utils.exceptions 

from astropy.time import Time 

from astropy.coordinates import AltAz 

 

from astro_metadata_translator import cache_translation, StubTranslator 

 

from .lsst import LSST_LOCATION, read_detector_ids, compute_detector_exposure_id_generic 

 

log = logging.getLogger(__name__) 

 

 

class LsstSimTranslator(StubTranslator): 

"""Shared routines for LSST Simulated Data. 

""" 

cameraPolicyFile = None 

"""Path to policy file relative to obs_lsst root.""" 

 

detectorMapping = None 

"""Mapping of detector name to detector number.""" 

 

@staticmethod 

def compute_detector_exposure_id(exposure_id, detector_num): 

"""Compute the detector exposure ID from detector number and 

exposure ID. 

 

This is a helper method to allow code working outside the translator 

infrastructure to use the same algorithm. 

 

Parameters 

---------- 

exposure_id : `int` 

Unique exposure ID. 

detector_num : `int` 

Detector number. 

 

Returns 

------- 

detector_exposure_id : `int` 

The calculated ID. 

""" 

return compute_detector_exposure_id_generic(exposure_id, detector_num, max_num=1000, 

mode="concat") 

 

@classmethod 

def compute_detector_num_from_name(cls, detector_group, detector_name): 

"""Helper method to return the detector number from the name. 

 

Parameters 

---------- 

detector_group : `str` 

Name of the detector grouping. This is generally the raft name. 

detector_name : `str` 

Detector name. 

 

Returns 

------- 

num : `int` 

Detector number. 

""" 

fullname = f"{detector_group}_{detector_name}" 

 

num = None 

if cls.cameraPolicyFile is not None: 

if cls.detectorMapping is None: 

cls.detectorMapping = read_detector_ids(cls.cameraPolicyFile) 

if fullname in cls.detectorMapping: 

num = cls.detectorMapping[fullname] 

else: 

log.warning(f"Unable to determine detector number from detector name {fullname}") 

 

return num 

 

@cache_translation 

def to_telescope(self): 

# Docstring will be inherited. Property defined in properties.py 

telescope = None 

if "OUTFILE" in self._header and self._header["OUTFILE"].startswith("lsst"): 

telescope = "LSST" 

self._used_these_cards("OUTFILE") 

elif "LSST_NUM" in self._header: 

telescope = "LSST" 

self._used_these_cards("LSST_NUM") 

return telescope 

 

@cache_translation 

def to_location(self): 

# Docstring will be inherited. Property defined in properties.py 

location = None 

tel = self.to_telescope() 

if tel == "LSST": 

location = LSST_LOCATION 

return location 

 

@cache_translation 

def to_datetime_begin(self): 

# Docstring will be inherited. Property defined in properties.py 

self._used_these_cards("MJD-OBS") 

return Time(self._header["MJD-OBS"], scale="tai", format="mjd") 

 

@cache_translation 

def to_datetime_end(self): 

# Docstring will be inherited. Property defined in properties.py 

return self.to_datetime_begin() + self.to_exposure_time() 

 

@cache_translation 

def to_detector_num(self): 

# Docstring will be inherited. Property defined in properties.py 

raft = self.to_detector_group() 

detector = self.to_detector_name() 

return self.compute_detector_num_from_name(raft, detector) 

 

@cache_translation 

def to_detector_exposure_id(self): 

exposure_id = self.to_exposure_id() 

num = self.to_detector_num() 

return self.compute_detector_exposure_id(exposure_id, num) 

 

@cache_translation 

def to_observation_type(self): 

# Docstring will be inherited. Property defined in properties.py 

obstype = self._header["IMGTYPE"] 

self._used_these_cards("IMGTYPE") 

obstype = obstype.lower() 

if obstype == "skyexp": 

obstype = "science" 

return obstype 

 

@cache_translation 

def to_altaz_begin(self): 

# Docstring will be inherited. Property defined in properties.py 

if self.to_observation_type() == "science": 

# Derive from RADec in absence of any other information 

radec = self.to_tracking_radec() 

if radec is not None: 

# This triggers warnings because of the future dates 

with warnings.catch_warnings(): 

warnings.simplefilter("ignore", category=astropy.utils.exceptions.AstropyWarning) 

altaz = radec.transform_to(AltAz) 

return altaz 

return None