Coverage for python/astro_metadata_translator/translators/fits.py : 25%
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# This file is part of astro_metadata_translator. # # Developed for the LSST Data Management System. # This product includes software developed by the LSST Project # (http://www.lsst.org). # See the LICENSE file at the top-level directory of this distribution # 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 translator for FITS standard headers.
Understands:
- DATE-OBS - INSTRUME - TELESCOP - OBSGEO-[X,Y,Z]
"""
# Direct translation from header key to standard form telescope="TELESCOP")
"""Indicate whether this translation class can translate the supplied header.
Checks the instrument value and compares with the supported instruments in the class
Parameters ---------- header : `dict`-like Header to convert to standardized form. filename : `str`, optional Name of file being translated.
Returns ------- can : `bool` `True` if the header is recognized by this class. `False` otherwise. """ if cls.supported_instrument is None: return False
# Protect against being able to always find a standard # header for instrument try: translator = cls(header, filename=filename) instrument = translator.to_instrument() except KeyError: return False
return instrument == cls.supported_instrument
"""Parse standard FITS ISO-style date string and return time object
Parameters ---------- date_str : `str` FITS format date string to convert to standard form. Bypasses lookup in the header. scale : `str`, optional Override the time scale from the TIMESYS header. Defaults to UTC. time_str : `str`, optional If provided, overrides any time component in the ``dateStr``, retaining the YYYY-MM-DD component and appending this time string, assumed to be of format HH:MM::SS.ss.
Returns ------- date : `astropy.time.Time` `~astropy.time.Time` representation of the date. """ if time_str is not None: date_str = "{}T{}".format(date_str[:10], time_str)
return Time(date_str, format="isot", scale=scale)
"""Calculate a date object from the named FITS header
Uses the TIMESYS header if present to determine the time scale, defaulting to UTC. Can be overridden since sometimes headers use TIMESYS for DATE- style headers but also have headers using different time scales.
Parameters ---------- date_key : `str` The key in the header representing a standard FITS ISO-style date. mjd_key : `str`, optional The key in the header representing a standard FITS MJD style date. This key will be tried if ``date_key`` is not found or can not be parsed. scale : `str`, optional Override value to use for the time scale in preference to TIMESYS or the default. Should be a form understood by `~astropy.time.Time`.
Returns ------- date : `astropy.time.Time` `~astropy.time.Time` representation of the date. """ used = [date_key, ] if scale is not None: pass elif self.is_key_ok("TIMESYS"): scale = self._header["TIMESYS"].lower() used.append("TIMESYS") else: scale = "utc" if self.is_key_ok(date_key): date_str = self._header[date_key] value = self._from_fits_date_string(date_str, scale=scale) self._used_these_cards(*used) elif self.is_key_ok(mjd_key): value = Time(self._header[mjd_key], scale=scale, format="mjd") else: value = None return value
def to_datetime_begin(self): """Calculate start time of observation.
Uses FITS standard ``MJD-OBS`` or ``DATE-OBS``, in conjunction with the ``TIMESYS`` header.
Returns ------- start_time : `astropy.time.Time` Time corresponding to the start of the observation. """ return self._from_fits_date("DATE-OBS", mjd_key="MJD-OBS")
def to_datetime_end(self): """Calculate end time of observation.
Uses FITS standard ``MJD-END`` or ``DATE-END``, in conjunction with the ``TIMESYS`` header.
Returns ------- start_time : `astropy.time.Time` Time corresponding to the end of the observation. """ return self._from_fits_date("DATE-END", mjd_key="MJD-END")
def to_location(self): """Calculate the observatory location.
Uses FITS standard ``OBSGEO-`` headers.
Returns ------- location : `astropy.coordinates.EarthLocation` An object representing the location of the telescope. """ cards = [f"OBSGEO-{c}" for c in ("X", "Y", "Z")] coords = [self._header[c] for c in cards] value = EarthLocation.from_geocentric(*coords, unit=u.m) self._used_these_cards(*cards) return value |