LsstCamTranslator

class lsst.obs.lsst.translators.LsstCamTranslator(header: Mapping[str, Any], filename: str | None = None)

Bases: LsstBaseTranslator

Metadata translation for the main LSST Camera.

Attributes Summary

DETECTOR_MAX	Maximum number of detectors to use when calculating the detector_exposure_id.
all_properties	All the valid properties for this translator including extensions.
cameraPolicyFile	Path to policy file relative to obs_lsst root.
default_resource_package	Module name to use to locate the correction resources.
default_resource_root	Default package resource path root to use to locate header correction files within the default_resource_package package.
default_search_path	Default search path to use to locate header correction files.
detectorMapping	Mapping of detector name to detector number and serial.
detectorSerials	Mapping of detector serial number to raft, number, and name.
extensions	Extension properties (str: PropertyDefinition)
name	Name of this translation class
supported_instrument	Supports the lsstCam instrument.
translators	All registered metadata translation classes.

Methods Summary

are_keys_ok(keywords)	Are the supplied keys all present and defined?.
can_translate(header[, filename])	Indicate whether this translation class can translate the supplied header.
can_translate_with_options(header, options)	Determine if a header can be translated with different criteria.
cards_used()	Cards used during metadata extraction.
compute_detector_exposure_id(exposure_id, ...)	Compute the detector exposure ID from detector number and exposure ID.
compute_detector_info_from_serial(...)	Helper method to return the detector information from the serial.
compute_detector_num_from_name(...)	Helper method to return the detector number from the name.
compute_exposure_id(dayobs, seqnum[, controller])	Helper method to calculate the exposure_id.
defined_in_this_class(name)	Report if the specified class attribute is defined specifically in this class.
detector_mapping()	Returns the mapping of full name to detector ID and serial.
detector_serials()	Obtain the mapping of detector serial to detector group, name, and number.
determine_translatable_headers(filename[, ...])	Given a file return all the headers usable for metadata translation.
determine_translator(header[, filename])	Determine a translation class by examining the header.
fix_header(header, instrument, obsid[, filename])	Fix LSSTCam headers.
is_key_ok(keyword)	Return True if the value associated with the named keyword is present in this header and defined.
is_keyword_defined(header, keyword)	Return True if the value associated with the named keyword is present in the supplied header and defined.
is_on_sky()	Determine if this is an on-sky observation.
max_detector_exposure_id()	The maximum detector exposure ID expected to be generated by this instrument.
max_exposure_id()	The maximum exposure ID expected from this instrument.
observing_date_to_observing_day(...)	Return the YYYYMMDD integer corresponding to the observing day.
observing_date_to_offset(observing_date)	Return the offset to use when calculating the observing day.
quantity_from_card(keywords, unit[, ...])	Calculate a Astropy Quantity from a header card and a unit.
resource_root()	Return package resource to use to locate correction resources within an installed package.
search_paths()	Search paths to use for LSST data when looking for header correction files.
to_altaz_begin()	Return value of altaz_begin from headers.
to_boresight_airmass()	Calculate airmass at boresight at start of observation.
to_boresight_rotation_angle()	Angle of the instrument in boresight_rotation_coord frame.
to_boresight_rotation_coord()	Boresight rotation angle.
to_can_see_sky()	Return whether the observation can see the sky or not.
to_dark_time()	Calculate the dark time.
to_datetime_begin()	Calculate start time of observation.
to_datetime_end()	Calculate end time of observation.
to_detector_exposure_id()	Return value of detector_exposure_id from headers.
to_detector_group()	Collection name of which this detector is a part.
to_detector_name()	Name of the detector within the instrument (might not be unique if there are detector groups).
to_detector_num()	Return value of detector_num from headers.
to_detector_serial()	Serial number/string associated with this detector.
to_detector_unique_name()	Return a unique name for the detector.
to_exposure_group()	Calculate the exposure group string.
to_exposure_id()	Generate a unique exposure ID number
to_exposure_time()	Duration of the exposure with shutter open (seconds).
to_focus_z()	Return the defocal distance of the camera in units of mm.
to_group_counter_end()	Return the observation counter of the observation that ends this group.
to_group_counter_start()	Return the observation counter of the observation that began this group.
to_has_simulated_content()	Return a boolean indicating whether any part of the observation was simulated.
to_instrument()	The instrument used to observe the exposure.
to_location()	Calculate the observatory location.
to_object()	Object of interest or field name.
to_observation_counter()	Return the sequence number within the observing day.
to_observation_id()	Label uniquely identifying this observation (can be related to 'exposure_id').
to_observation_reason()	Return the reason this observation was taken.
to_observation_type()	Return value of observation_type from headers.
to_observing_day()	Return the day of observation as YYYYMMDD integer.
to_observing_day_offset()	Return the offset required to calculate observing day.
to_physical_filter()	Calculate the physical filter name.
to_pressure()	Return value of pressure from headers.
to_relative_humidity()	Return value of relative_humidity from headers.
to_science_program()	Observing program (survey or proposal) identifier.
to_telescope()	Full name of the telescope.
to_temperature()	Return value of temperature from headers.
to_tracking_radec()	Return value of tracking_radec from headers.
to_visit_id()	Calculate the visit associated with this exposure.
translator_version()	Return the version string for this translator class.
unpack_exposure_id(exposure_id)	Unpack an exposure ID into dayobs, seqnum, and controller.
validate_value(value, default[, minimum, ...])	Validate the supplied value, returning a new value if out of range.

Attributes Documentation

DETECTOR_MAX = 1000

Maximum number of detectors to use when calculating the detector_exposure_id.

Note that because this is the maximum number of detectors, for zero-based detector_num values this is one greater than the maximum detector_num. It is also often rounded up to the nearest power of 10 anyway, to allow detector_exposure_id values to be easily decoded by humans.

all_properties: dict[str, PropertyDefinition] = {'altaz_begin': PropertyDefinition(doc='Telescope boresight azimuth and elevation at start of observation.', str_type='astropy.coordinates.AltAz', py_type=<class 'astropy.coordinates.builtin_frames.altaz.AltAz'>, to_simple=<function altaz_to_simple>, from_simple=<function simple_to_altaz>), 'boresight_airmass': PropertyDefinition(doc='Airmass of the boresight of the telescope.', str_type='float', py_type=<class 'float'>, to_simple=None, from_simple=None), 'boresight_rotation_angle': PropertyDefinition(doc='Angle of the instrument in boresight_rotation_coord frame.', str_type='astropy.coordinates.Angle', py_type=<class 'astropy.coordinates.angles.core.Angle'>, to_simple=<function angle_to_simple>, from_simple=<function simple_to_angle>), 'boresight_rotation_coord': PropertyDefinition(doc='Coordinate frame of the instrument rotation angle (options: sky, unknown).', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'can_see_sky': PropertyDefinition(doc='True if the observation is looking at sky, False if it is definitely not looking at the sky. None indicates that it is not known whether sky could be seen.', str_type='bool', py_type=<class 'bool'>, to_simple=None, from_simple=None), 'dark_time': PropertyDefinition(doc='Duration of the exposure with shutter closed (seconds).', str_type='astropy.units.Quantity', py_type=<class 'astropy.units.quantity.Quantity'>, to_simple=<function exptime_to_simple>, from_simple=<function simple_to_exptime>), 'datetime_begin': PropertyDefinition(doc='Time of the start of the observation.', str_type='astropy.time.Time', py_type=<class 'astropy.time.core.Time'>, to_simple=<function datetime_to_simple>, from_simple=<function simple_to_datetime>), 'datetime_end': PropertyDefinition(doc='Time of the end of the observation.', str_type='astropy.time.Time', py_type=<class 'astropy.time.core.Time'>, to_simple=<function datetime_to_simple>, from_simple=<function simple_to_datetime>), 'detector_exposure_id': PropertyDefinition(doc='Unique integer identifier for this detector in this exposure.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'detector_group': PropertyDefinition(doc='Collection name of which this detector is a part. Can be None if there are no detector groupings.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'detector_name': PropertyDefinition(doc='Name of the detector within the instrument (might not be unique if there are detector groups).', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'detector_num': PropertyDefinition(doc='Unique (for instrument) integer identifier for the sensor.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'detector_serial': PropertyDefinition(doc='Serial number/string associated with this detector.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'detector_unique_name': PropertyDefinition(doc='Unique name of the detector within the focal plane, generally combining detector_group with detector_name.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'exposure_group': PropertyDefinition(doc="Label to use to associate this exposure with others (can be related to 'exposure_id').", str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'exposure_id': PropertyDefinition(doc='Unique (with instrument) integer identifier for this observation.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'exposure_time': PropertyDefinition(doc='Duration of the exposure with shutter open (seconds).', str_type='astropy.units.Quantity', py_type=<class 'astropy.units.quantity.Quantity'>, to_simple=<function exptime_to_simple>, from_simple=<function simple_to_exptime>), 'focus_z': PropertyDefinition(doc='Defocal distance.', str_type='astropy.units.Quantity', py_type=<class 'astropy.units.quantity.Quantity'>, to_simple=<function focusz_to_simple>, from_simple=<function simple_to_focusz>), 'group_counter_end': PropertyDefinition(doc='Observation counter for the end of the exposure group. Depending on the instrument the relevant group may be visit_id or exposure_group.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'group_counter_start': PropertyDefinition(doc='Observation counter for the start of the exposure group.Depending on the instrument the relevant group may be visit_id or exposure_group.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'has_simulated_content': PropertyDefinition(doc='Boolean indicating whether any part of this observation was simulated.', str_type='bool', py_type=<class 'bool'>, to_simple=None, from_simple=None), 'instrument': PropertyDefinition(doc='The instrument used to observe the exposure.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'location': PropertyDefinition(doc='Location of the observatory.', str_type='astropy.coordinates.EarthLocation', py_type=<class 'astropy.coordinates.earth.EarthLocation'>, to_simple=<function earthlocation_to_simple>, from_simple=<function simple_to_earthlocation>), 'object': PropertyDefinition(doc='Object of interest or field name.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'observation_counter': PropertyDefinition(doc='Counter of this observation. Can be counter within observing_day or a global counter. Likely to be observatory specific.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'observation_id': PropertyDefinition(doc="Label uniquely identifying this observation (can be related to 'exposure_id').", str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'observation_reason': PropertyDefinition(doc="Reason this observation was taken, or its purpose ('science' and 'calibration' are common values)", str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'observation_type': PropertyDefinition(doc='Type of observation (currently: science, dark, flat, bias, focus).', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'observing_day': PropertyDefinition(doc='Integer in YYYYMMDD format corresponding to the day of observation.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None), 'observing_day_offset': PropertyDefinition(doc='Offset to subtract from an observation date when calculating the observing day. Conversely, the offset to add to an observing day when calculating the time span of a day.', str_type='astropy.time.TimeDelta', py_type=<class 'astropy.time.core.TimeDelta'>, to_simple=<function timedelta_to_simple>, from_simple=<function simple_to_timedelta>), 'physical_filter': PropertyDefinition(doc='The bandpass filter used for this observation.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'pressure': PropertyDefinition(doc='Atmospheric pressure outside the dome.', str_type='astropy.units.Quantity', py_type=<class 'astropy.units.quantity.Quantity'>, to_simple=<function pressure_to_simple>, from_simple=<function simple_to_pressure>), 'relative_humidity': PropertyDefinition(doc='Relative humidity outside the dome.', str_type='float', py_type=<class 'float'>, to_simple=None, from_simple=None), 'science_program': PropertyDefinition(doc='Observing program (survey or proposal) identifier.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'telescope': PropertyDefinition(doc='Full name of the telescope.', str_type='str', py_type=<class 'str'>, to_simple=None, from_simple=None), 'temperature': PropertyDefinition(doc='Temperature outside the dome.', str_type='astropy.units.Quantity', py_type=<class 'astropy.units.quantity.Quantity'>, to_simple=<function temperature_to_simple>, from_simple=<function simple_to_temperature>), 'tracking_radec': PropertyDefinition(doc='Requested RA/Dec to track.', str_type='astropy.coordinates.SkyCoord', py_type=<class 'astropy.coordinates.sky_coordinate.SkyCoord'>, to_simple=<function skycoord_to_simple>, from_simple=<function simple_to_skycoord>), 'visit_id': PropertyDefinition(doc='ID of the Visit this Exposure is associated with.\n\nScience observations should essentially always be\nassociated with a visit, but calibration observations\nmay not be.', str_type='int', py_type=<class 'int'>, to_simple=None, from_simple=None)}

All the valid properties for this translator including extensions.

cameraPolicyFile = 'policy/lsstCam.yaml'

Path to policy file relative to obs_lsst root.

default_resource_package = 'astro_metadata_translator'

Module name to use to locate the correction resources.

default_resource_root: str | None = None

Default package resource path root to use to locate header correction files within the default_resource_package package.

default_search_path: Sequence[str] | None = None

Default search path to use to locate header correction files.

detectorMapping = None

Mapping of detector name to detector number and serial.

detectorSerials = None

Mapping of detector serial number to raft, number, and name.

extensions: dict[str, PropertyDefinition] = {}

Extension properties (str: PropertyDefinition)

Some instruments have important properties beyond the standard set; this is the place to declare that they exist, and they will be treated in the same way as the standard set, except that their names will everywhere be prefixed with ext_.

Each property is indexed by name (str), with a corresponding PropertyDefinition.

name: str | None = 'LSSTCam'

Name of this translation class

supported_instrument: str | None = 'LSSTCam'

Supports the lsstCam instrument.

translators: dict[str, type[MetadataTranslator]] = {'DECam': <class 'astro_metadata_translator.translators.decam.DecamTranslator'>, 'HSC': <class 'astro_metadata_translator.translators.hsc.HscTranslator'>, 'LSST-TS3': <class 'lsst.obs.lsst.translators.ts3.LsstTS3Translator'>, 'LSST-TS8': <class 'lsst.obs.lsst.translators.ts8.LsstTS8Translator'>, 'LSST-UCDCam': <class 'lsst.obs.lsst.translators.lsst_ucdcam.LsstUCDCamTranslator'>, 'LSSTCam': <class 'lsst.obs.lsst.translators.lsstCam.LsstCamTranslator'>, 'LSSTCam-PhoSim': <class 'lsst.obs.lsst.translators.phosim.LsstCamPhoSimTranslator'>, 'LSSTCam-imSim': <class 'lsst.obs.lsst.translators.imsim.LsstCamImSimTranslator'>, 'LSSTComCam': <class 'lsst.obs.lsst.translators.comCam.LsstComCamTranslator'>, 'LSSTComCamSim': <class 'lsst.obs.lsst.translators.comCamSim.LsstComCamSimTranslator'>, 'LSST_LATISS': <class 'lsst.obs.lsst.translators.latiss.LatissTranslator'>, 'MegaPrime': <class 'astro_metadata_translator.translators.megaprime.MegaPrimeTranslator'>, 'SDSS': <class 'astro_metadata_translator.translators.sdss.SdssTranslator'>, 'SuprimeCam': <class 'astro_metadata_translator.translators.suprimecam.SuprimeCamTranslator'>}

All registered metadata translation classes.

Methods Documentation

are_keys_ok(keywords: Iterable[str]) → bool

Are the supplied keys all present and defined?.

Parameters:

keywordsiterable of str

Keywords to test.

Returns:

all_okbool

True if all supplied keys are present and defined.

classmethod can_translate(header, filename=None)

Indicate whether this translation class can translate the supplied header.

Parameters:

headerdict-like

Header to convert to standardized form.

filenamestr, optional

Name of file being translated.

Returns:

canbool

True if the header is recognized by this class. False otherwise.

classmethod can_translate_with_options(header: Mapping[str, Any], options: dict[str, Any], filename: str | None = None) → bool

Determine if a header can be translated with different criteria.

Parameters:

headerdict-like

Header to convert to standardized form.

optionsdict

Headers to try to determine whether this header can be translated by this class. If a card is found it will be compared with the expected value and will return that comparison. Each card will be tried in turn until one is found.

filenamestr, optional

Name of file being translated.

Returns:

canbool

True if the header is recognized by this class. False otherwise.

Notes

Intended to be used from within can_translate implementations for specific translators. Is not intended to be called directly from determine_translator.

cards_used() → frozenset[str]

Cards used during metadata extraction.

Returns:

usedfrozenset of str

Cards used when extracting metadata.

classmethod 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_idint

Unique exposure ID.

detector_numint

Detector number.

Returns:

detector_exposure_idint

The calculated ID.

classmethod compute_detector_info_from_serial(detector_serial)

Helper method to return the detector information from the serial.

Parameters:

detector_serialstr

Detector serial ID.

Returns:

infotuple of (str, str, int)

Detector group, name, and number.

classmethod compute_detector_num_from_name(detector_group, detector_name)

Helper method to return the detector number from the name.

Parameters:

detector_groupstr

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

detector_namestr

Detector name.

Returns:

numint

Detector number.

static compute_exposure_id(dayobs, seqnum, controller=None)

Helper method to calculate the exposure_id.

Parameters:

dayobsstr or int

Day of observation in either YYYYMMDD or YYYY-MM-DD format. If the string looks like ISO format it will be truncated before the T before being handled.

seqnumint or str

Sequence number.

controllerstr, optional

Controller to use. If this is “O”, no change is made to the exposure ID. If it is “C” a 1000 is added to the year component of the exposure ID. If it is “H” a 2000 is added to the year component. This sequence continues with “P” and “Q” controllers. None indicates that the controller is not relevant to the exposure ID calculation (generally this is the case for test stand data).

Returns:

exposure_idint

Exposure ID in form YYYYMMDDnnnnn form.

classmethod defined_in_this_class(name: str) → bool | None

Report if the specified class attribute is defined specifically in this class.

Parameters:

namestr

Name of the attribute to test.

Returns:

in_classbool

True if there is a attribute of that name defined in this specific subclass. False if the method is not defined in this specific subclass but is defined in a parent class. Returns None if the attribute is not defined anywhere in the class hierarchy (which can happen if translators have typos in their mapping tables).

Notes

Retrieves the attribute associated with the given name. Then looks in all the parent classes to determine whether that attribute comes from a parent class or from the current class. Attributes are compared using id().

classmethod detector_mapping()

Returns the mapping of full name to detector ID and serial.

Returns:

mappingdict of str:tuple

Returns the mapping of full detector name (group+detector) to detector number and serial.

Raises:

ValueError

Raised if no camera policy file has been registered with this translation class.

Notes

Will construct the mapping if none has previously been constructed.

classmethod detector_serials()

Obtain the mapping of detector serial to detector group, name, and number.

Returns:

infodict of tuple of (str, str, int)

A dict with the serial numbers as keys and values of detector group, name, and number.

classmethod determine_translatable_headers(filename: str, primary: MutableMapping[str, Any] | None = None) → Iterator[MutableMapping[str, Any]]

Given a file return all the headers usable for metadata translation.

This method can optionally be given a header from the file. This header will generally be the primary header or a merge of the first two headers.

In the base class implementation it is assumed that this supplied header is the only useful header for metadata translation and it will be returned unchanged if given. This can avoid unnecessarily re-opening the file and re-reading the header when the content is already known.

If no header is supplied, a header will be read from the supplied file using read_basic_metadata_from_file, allowing it to merge the primary and secondary header of a multi-extension FITS file. Subclasses can read the header from the data file using whatever technique is best for that instrument.

Subclasses can return multiple headers and ignore the externally supplied header. They can also merge it with another header and return a new derived header if that is required by the particular data file. There is no requirement for the supplied header to be used.

Parameters:

filenamestr

Path to a file in a format understood by this translator.

primarydict-like, optional

The primary header obtained by the caller. This is sometimes already known, for example if a system is trying to bootstrap without already knowing what data is in the file. For many instruments where the primary header is the only relevant header, the primary header will be returned with no further action.

Yields:

headersiterator of dict-like

A header usable for metadata translation. For this base implementation it will be either the supplied primary header or a header read from the file. This implementation will only ever yield a single header.

Notes

Each translator class can have code specifically tailored to its own file format. It is important not to call this method with an incorrect translator class. The normal paradigm is for the caller to have read the first header and then called determine_translator() on the result to work out which translator class to then call to obtain the real headers to be used for translation.

classmethod determine_translator(header: Mapping[str, Any], filename: str | None = None) → type[astro_metadata_translator.translator.MetadataTranslator]

Determine a translation class by examining the header.

Parameters:

headerdict-like

Representation of a header.

filenamestr, optional

Name of file being translated.

Returns:

translatorMetadataTranslator

Translation class that knows how to extract metadata from the supplied header.

Raises:

ValueError

None of the registered translation classes understood the supplied header.

classmethod fix_header(header, instrument, obsid, filename=None)

Fix LSSTCam headers.

Notes

See fix_header for details of the general process.

is_key_ok(keyword: str | None) → bool

Return True if the value associated with the named keyword is present in this header and defined.

Parameters:

keywordstr

Keyword to check against header.

Returns:

is_okbool

True if the header is present and not-None. False otherwise.

static is_keyword_defined(header: Mapping[str, Any], keyword: str | None) → bool

Return True if the value associated with the named keyword is present in the supplied header and defined.

Parameters:

headerdict-lik

Header to use as reference.

keywordstr

Keyword to check against header.

Returns:

is_definedbool

True if the header is present and not-None. False otherwise.

is_on_sky()

Determine if this is an on-sky observation.

Returns:

is_on_skybool

Returns True if this is a observation on sky on the summit.

classmethod max_detector_exposure_id()

The maximum detector exposure ID expected to be generated by this instrument.

Returns:

max_idint

The maximum value.

classmethod max_exposure_id()

The maximum exposure ID expected from this instrument.

Returns:

max_exposure_idint

The maximum value.

classmethod observing_date_to_observing_day(observing_date: Time, offset: TimeDelta | int | None) → int

Return the YYYYMMDD integer corresponding to the observing day.

The offset is subtracted from the time of observation before calculating the year, month and day.

Parameters:

observing_dateastropy.time.Time

The observation date.

offsetastropy.time.TimeDelta | numbers.Real | None

The offset to subtract from the observing date when calculating the observing day. If a plain number is given it is taken to be in units of seconds. If None no offset is applied.

Returns:

dayint

The observing day as an integer of form YYYYMMDD.

Notes

For example, if the offset is +12 hours both 2023-07-06T13:00 and 2023-07-07T11:00 will return an observing day of 20230706 because the observing day goes from 2023-07-06T12:00 to 2023-07-07T12:00.

classmethod observing_date_to_offset(observing_date: Time) → TimeDelta | None

Return the offset to use when calculating the observing day.

Parameters:

observing_dateastropy.time.Time

The date of the observation. Unused.

Returns:

offsetastropy.time.TimeDelta

The offset to apply. During lab testing the offset is Pacific Time which can mean UTC-7 or UTC-8 depending on daylight savings. In Chile the offset is always UTC-12.

quantity_from_card(keywords: str | Sequence[str], unit: Unit, default: float | None = None, minimum: float | None = None, maximum: float | None = None, checker: Callable | None = None) → Quantity

Calculate a Astropy Quantity from a header card and a unit.

Parameters:

keywordsstr or list of str

Keyword to use from header. If a list each keyword will be tried in turn until one matches.

unitastropy.units.UnitBase

Unit of the item in the header.

defaultfloat, optional

Default value to use if the header value is invalid. Assumed to be in the same units as the value expected in the header. If None, no default value is used.

minimumfloat, optional

Minimum possible valid value, optional. If the calculated value is below this value, the default value will be used.

maximumfloat, optional

Maximum possible valid value, optional. If the calculated value is above this value, the default value will be used.

checkerCallable, optional

Callback function to be used by the translator method in case the keyword is not present. Function will be executed as if it is a method of the translator class. Running without raising an exception will allow the default to be used. Should usually raise KeyError.

Returns:

qastropy.units.Quantity

Quantity representing the header value.

Raises:

KeyError

The supplied header key is not present.

resource_root() → tuple[str | None, str | None]

Return package resource to use to locate correction resources within an installed package.

Returns:

resource_packagestr

Package resource name. None if no package resource are to be used.

resource_rootstr

The name of the resource root. None if no package resources are to be used.

search_paths()

Search paths to use for LSST data when looking for header correction files.

Returns:

pathlist

List with a single element containing the full path to the corrections directory within the obs_lsst package.

to_altaz_begin() → Any

Return value of altaz_begin from headers.

Telescope boresight azimuth and elevation at start of observation.

Returns:

altaz_beginastropy.coordinates.AltAz

The translated property.

to_boresight_airmass() → Any

Calculate airmass at boresight at start of observation.

Notes

Early data are missing AMSTART header so we fall back to calculating it from ELSTART.

to_boresight_rotation_angle() → Any

Angle of the instrument in boresight_rotation_coord frame.

Returns:

translationastropy.coordinates.Angle

Translated value derived from the header.

to_boresight_rotation_coord() → Any

Boresight rotation angle.

Only relevant for science observations.

to_can_see_sky() → Any

Return whether the observation can see the sky or not.

Returns:

can_see_skybool or None

True if the detector is receiving photons from the sky. False if the sky is not visible to the detector. None if the metadata translator does not know one way or the other.

Notes

The base class translator uses a simple heuristic of returning True if the observation type is “science” or “object” and False if the observation type is “bias” or “dark”. For all other cases it will return None.

to_dark_time() → Any

Calculate the dark time.

If a DARKTIME header is not found, the value is assumed to be identical to the exposure time.

Returns:

darkastropy.units.Quantity

The dark time in seconds.

to_datetime_begin() → Any

Calculate start time of observation.

Uses FITS standard MJD-BEG or DATE-BEG, in conjunction with the TIMESYS header. Will fallback to using MJD-OBS or DATE-OBS if the -BEG variants are not found.

Returns:

start_timeastropy.time.Time or None

Time corresponding to the start of the observation. Returns None if no date can be found.

to_datetime_end() → Any

Calculate end time of observation.

Uses FITS standard MJD-END or DATE-END, in conjunction with the TIMESYS header.

Returns:

start_timeastropy.time.Time

Time corresponding to the end of the observation.

to_detector_exposure_id() → Any

Return value of detector_exposure_id from headers.

Unique integer identifier for this detector in this exposure.

Returns:

detector_exposure_idint

The translated property.

to_detector_group() → Any

Collection name of which this detector is a part. Can be None if there are no detector groupings.

Returns:

translationstr

Translated value derived from the header.

to_detector_name() → Any

Name of the detector within the instrument (might not be unique if there are detector groups).

Returns:

translationstr

Translated value derived from the header.

to_detector_num() → Any

Return value of detector_num from headers.

Unique (for instrument) integer identifier for the sensor.

Returns:

detector_numint

The translated property.

to_detector_serial() → Any

Serial number/string associated with this detector.

Returns:

translationstr

Translated value derived from the header.

to_detector_unique_name() → Any

Return a unique name for the detector.

Base class implementation attempts to combine detector_name with detector_group. Group is only used if not None.

Can be over-ridden by specialist translator class.

Returns:

namestr

detector_group``_``detector_name if detector_group is defined, else the detector_name is assumed to be unique. If neither return a valid value an exception is raised.

Raises:

NotImplementedError

Raised if neither detector_name nor detector_group is defined.

to_exposure_group() → Any

Calculate the exposure group string.

For LSSTCam and LATISS this is read from the GROUPID header. If that header is missing the exposure_id is returned instead as a string.

to_exposure_id() → Any

Generate a unique exposure ID number

This is a combination of DAYOBS and SEQNUM, and optionally CONTRLLR.

Returns:

exposure_idint

Unique exposure number.

to_exposure_time() → Any

Duration of the exposure with shutter open (seconds).

Returns:

translationastropy.units.Quantity

Translated value derived from the header.

to_focus_z() → Any

Return the defocal distance of the camera in units of mm. If there is no FOCUSZ value in the header it will return the default 0.0mm value.

Returns:

focus_z: astropy.units.Quantity

The defocal distance from header in mm or the 0.0mm default

to_group_counter_end() → Any

Return the observation counter of the observation that ends this group.

The definition of the relevant group is up to the metadata translator. It can be the last observation in the exposure_group or the last observation in the visit, but must be derivable from the metadata of this observation. It is of course possible that the last observation in the group does not exist if a sequence of observations was not completed.

Returns:

counterint

The observation counter for the end of the relevant group. Default implementation always returns the observation counter of this observation.

to_group_counter_start() → Any

Return the observation counter of the observation that began this group.

The definition of the relevant group is up to the metadata translator. It can be the first observation in the exposure_group or the first observation in the visit, but must be derivable from the metadata of this observation.

Returns:

counterint

The observation counter for the start of the relevant group. Default implementation always returns the observation counter of this observation.

to_has_simulated_content() → Any

Return a boolean indicating whether any part of the observation was simulated.

Returns:

is_simulatedbool

True if this exposure has simulated content. This can be if some parts of the metadata or data were simulated. Default implementation always returns False.

to_instrument() → Any

The instrument used to observe the exposure.

Returns:

translationstr

Translated property.

to_location() → Any

Calculate the observatory location.

Uses FITS standard OBSGEO- headers.

Returns:

locationastropy.coordinates.EarthLocation

An object representing the location of the telescope.

to_object() → Any

Object of interest or field name.

Returns:

translationstr

Translated value derived from the header.

to_observation_counter() → Any

Return the sequence number within the observing day.

Returns:

counterint

The sequence number for this day.

to_observation_id() → Any

Label uniquely identifying this observation (can be related to ‘exposure_id’).

Returns:

translationstr

Translated value derived from the header.

to_observation_reason() → Any

Return the reason this observation was taken.

Base class implementation returns the science if the observation_type is science, else unknown. A subclass may do something different.

Returns:

namestr

The reason for this observation.

to_observation_type() → Any

Return value of observation_type from headers.

Type of observation (currently: science, dark, flat, bias, focus).

Returns:

observation_typestr

The translated property.

to_observing_day() → Any

Return the day of observation as YYYYMMDD integer.

For LSSTCam and other compliant instruments this is the value of the DAYOBS header.

Returns:

obs_dayint

The day of observation.

to_observing_day_offset() → Any

Return the offset required to calculate observing day.

Base class implementation returns None.

Returns:

offsetastropy.time.TimeDelta or None

The offset to apply. Returns None if the offset is not defined.

Notes

This offset must be subtracted from a time of observation to calculate the observing day. This offset must be added to the YYYYMMDDT00:00 observing day to calculate the time span coverage of the observing day.

to_physical_filter() → Any

Calculate the physical filter name.

Returns:

filterstr

Name of filter. Can be a combination of FILTER, FILTER1, and FILTER2 headers joined by a “~”. Trailing “~empty” components are stripped. Returns “unknown” if no filter is declared.

to_pressure() → Any

Return value of pressure from headers.

Atmospheric pressure outside the dome.

Returns:

pressureastropy.units.Quantity

The translated property.

to_relative_humidity() → Any

Return value of relative_humidity from headers.

Relative humidity outside the dome.

Returns:

relative_humidityfloat

The translated property.

to_science_program() → Any

Observing program (survey or proposal) identifier.

Returns:

translationstr

Translated value derived from the header.

to_telescope() → Any

Full name of the telescope.

Returns:

translationstr

Translated property.

to_temperature() → Any

Return value of temperature from headers.

Temperature outside the dome.

Returns:

temperatureastropy.units.Quantity

The translated property.

to_tracking_radec() → Any

Return value of tracking_radec from headers.

Requested RA/Dec to track.

Returns:

tracking_radecastropy.coordinates.SkyCoord

The translated property.

to_visit_id() → Any

Calculate the visit associated with this exposure.

Notes

For LATISS and LSSTCam the default visit is derived from the exposure group. For other instruments we return the exposure_id.

classmethod translator_version() → str

Return the version string for this translator class.

Returns:

versionstr

String identifying the version of this translator.

Notes

Assumes that the version is available from the __version__ variable in the parent module. If this is not the case a translator should subclass this method.

static unpack_exposure_id(exposure_id)

Unpack an exposure ID into dayobs, seqnum, and controller.

Parameters:

exposure_idint

Integer exposure ID produced by compute_exposure_id.

Returns:

dayobsstr

Day of observation as a YYYYMMDD string.

seqnumint

Sequence number.

controllerstr

Controller code. Will be O (but should be ignored) for IDs produced by calling compute_exposure_id with controller=None.

static validate_value(value: float, default: float, minimum: float | None = None, maximum: float | None = None) → float

Validate the supplied value, returning a new value if out of range.

Parameters:

valuefloat

Value to be validated.

defaultfloat

Default value to use if supplied value is invalid or out of range. Assumed to be in the same units as the value expected in the header.

minimumfloat

Minimum possible valid value, optional. If the calculated value is below this value, the default value will be used.

maximumfloat

Maximum possible valid value, optional. If the calculated value is above this value, the default value will be used.

Returns:

valuefloat

Either the supplied value, or a default value.