ObsCoreRecord¶

class pyvo.dal.ObsCoreRecord(results, index, *, session=None)[source]¶

Bases: SodaRecordMixin, DatalinkRecordMixin, Record, ObsCoreMetadata

a dictionary-like container for data in a record from the results of an image (SIA2) search, describing an available image in ObsCore format.

The commonly accessed metadata which are stadardized by the SIA2 protocol are available as attributes. If the metadatum accessible via an attribute is not available, the value of that attribute will be None. All metadata, including non-standard metadata, are also acessible via the get( key ) function (or the [key] operator) where key is table column name.

Attributes Summary

`access_estsize`	The approximate size (in kilobytes) of the file available via the access_url.
`access_format`	Content format of the dataset.
`access_url`	The access_url column contains a URL that can be used to download the data product (as a file of some sort).
`bib_reference`	URL or bibcode for documentation.
`calib_level`	Calibration level of the observation: in {0, 1, 2, 3, 4}
`data_rights`	This parameter allows mentioning the availability of a dataset.
`dataproduct_subtype`	Data product more specific type
`dataproduct_type`	Data product (file content) primary type.
`em_calib_status`	This attribute of the spectral axis indicates the status of the data in terms of spectral calibration.
`em_max`	Maximum of the spectral interval covered by the observation
`em_min`	Minimum of the spectral interval covered by the observation
`em_res_power`	Average estimation for the spectral resolution power stored as a double value, with no unit.
`em_res_power_max`	Resolving power max value on spectral axis
`em_res_power_min`	Resolving power min value on spectral axis
`em_resolution`	A mean estimate of the resolution, e.g.
`em_stat_error`	Spectral coord statistical error (accuracy along the spectral axis)
`em_ucd`	Nature of the spectral axis
`em_unit`	Units along the spectral axis
`em_xel`	Number of elements along the spectral axis
`facility_name`	Name of the facility or observatory used to collect the data
`instrument_name`	The name of the instrument used for the acquisition of the data
`o_calib_status`	Type of calibration applied on the Flux observed (or other observable quantity).
`o_stat_error`	Statistical error on the Observable axis.
`o_ucd`	Nature of the observable axis within the data product
`o_unit`	Units along the observable axis
`obs_collection`	The name of the collection (DataID.Collection) identifies the data collection to which the data product belongs.
`obs_create_date`	Date when the dataset was created
`obs_creator_did`	IVOA dataset identifier given by its creator.
`obs_creator_name`	The name of the institution or entity which created the dataset.
`obs_id`	Collection specific internal ID given by the ObsTAP service
`obs_publisher_did`	ID for the Dataset assigned by the publisher.
`obs_release_date`	Observation release date
`obs_title`	Brief description of dataset in free format
`pol_states`	List of polarization states present in the data file.
`pol_xel`	Number of different polarization states present in the data.
`proposal_id`	Identifier of proposal to which observation belongs
`publisher_id`	IVOA-ID for the Publisher.
`s_calib_status`	A string to encode the calibration status along the spatial axis (astrometry).
`s_dec`	CRS Declination of the center of the observation
`s_fov`	Approximate size of the covered region as the diameter of a containing circle.
`s_pixel_scale`	This corresponds to the sampling precision of the data along the spatial axis.
`s_ra`	ICRS Right Ascension of the center of the observation
`s_region`	Sky region covered by the data product (expressed in ICRS frame).
`s_resolution`	Spatial resolution of data specifies a reference value chosen by the data provider for the estimated spatial resolution of the data product in arcseconds.
`s_resolution_max`	Resolution max value on spatial axis (FHWM of PSF)
`s_resolution_min`	Resolution min value on spatial axis (FHWM of PSF)
`s_stat_error`	This parameter gives an estimate of the astrometric statistical error after the astrometric calibration phase.
`s_ucd`	UCD for the nature of the spatial axis (pos or u,v data)
`s_unit`	Unit used for spatial axis
`s_xel1`	Number of elements along the first spatial axis
`s_xel2`	Number of elements along the second spatial axis
`t_calib_status`	Type of time coordinate calibration.
`t_exptime`	Total exposure time. For simple exposures, this is just the time_bounds
`t_max`	The stop time of the observation specified in MJD as an `Time` instance.
`t_min`	The start time of the observation specified in MJD as an `Time` instance.
`t_ref_pos`	Time Axis Reference Position as defined in STC REC, Section 4.4.1.1.1
`t_resolution`	Estimated or average value of the temporal resolution.
`t_stat_error`	Time coord statistical error on the time measurements in seconds
`t_xel`	Number of elements along the time axis
`target_class`	This field indicates the type of object that was pointed for this observation.
`target_name`	The target_name attribute contains the name of the target of the observation, if any.

Attributes Documentation

access_estsize¶: The approximate size (in kilobytes) of the file available via the access_url. This is used only to gain some idea of the size of a data product before downloading it, hence only an approximate value is required. Provision of dataset size estimates is important whenever it is possible that datasets can be very large.

access_format¶: Content format of the dataset. The value of access_format should be a MIME type, either a standard MIME type, an extended MIME type from the above table, or a new custom MIME type defined by the data provider.

access_url¶: The access_url column contains a URL that can be used to download the data product (as a file of some sort). Access URLs are not guaranteed to remain valid and unchanged indefinitely. To access a specific data product after a period of time (e.g., days or weeks) a query should be performed to obtain a fresh access URL.

bib_reference¶: URL or bibcode for documentation. This is a forward link to major publications which reference the dataset.

calib_level¶: Calibration level of the observation: in {0, 1, 2, 3, 4}

data_rights¶: This parameter allows mentioning the availability of a dataset. Possible values are: public, secure, or proprietary.

dataproduct_subtype¶: Data product more specific type

dataproduct_type¶: Data product (file content) primary type. This is coded as a string that conveys a general idea of the content and organization of a dataset.

em_calib_status¶: This attribute of the spectral axis indicates the status of the data in terms of spectral calibration. Possible values are defined in the Characterisation Data Model and belong to {uncalibrated , calibrated, relative, absolute}.

em_max¶: Maximum of the spectral interval covered by the observation

em_min¶: Minimum of the spectral interval covered by the observation

em_res_power¶: Average estimation for the spectral resolution power stored as a double value, with no unit.

em_res_power_max¶: Resolving power max value on spectral axis

em_res_power_min¶: Resolving power min value on spectral axis

em_resolution¶: A mean estimate of the resolution, e.g. Full Width at Half Maximum (FWHM) of the Line Spread Function (or LSF). This can be used for narrow range spectra whereas in the majority of cases, the resolution power is preferable due to the LSF variation along the spectral axis.

em_stat_error¶: Spectral coord statistical error (accuracy along the spectral axis)

em_ucd¶: Nature of the spectral axis

em_unit¶: Units along the spectral axis

em_xel¶: Number of elements along the spectral axis

facility_name¶: Name of the facility or observatory used to collect the data

instrument_name¶: The name of the instrument used for the acquisition of the data

o_calib_status¶: Type of calibration applied on the Flux observed (or other observable quantity).

o_stat_error¶: Statistical error on the Observable axis. Note: the return value has the units defined in unit

o_ucd¶: Nature of the observable axis within the data product

o_unit¶: Units along the observable axis

obs_collection¶: The name of the collection (DataID.Collection) identifies the data collection to which the data product belongs. A data collection can be any collection of datasets which are alike in some fashion. Typical data collections might be all the data from a particular telescope, instrument, or survey. The value is either the registered shortname for the data collection, the full registered IVOA identifier for the collection, or a data provider defined short name for the collection. Examples: HST/WFPC2, VLT/FORS2, CHANDRA/ACIS-S, etc.

obs_create_date¶: Date when the dataset was created

obs_creator_did¶: IVOA dataset identifier given by its creator.

obs_creator_name¶: The name of the institution or entity which created the dataset.

obs_id¶: Collection specific internal ID given by the ObsTAP service

obs_publisher_did¶: ID for the Dataset assigned by the publisher. Note that data from a source (creator_did) can be published by multiple publishers and have assigned multiple publisher data IDs.

obs_release_date¶: Observation release date

obs_title¶: Brief description of dataset in free format

pol_states¶: List of polarization states present in the data file. Possible values are: {I Q U V RR LL RL LR XX YY XY YX POLI POLA}. Values in the set are separated by the ‘/’ character. A leading / character must start the list and a trailing / character must end it. It should be ordered following the above list, compatible with the FITS list table for polarization definition.

pol_xel¶: Number of different polarization states present in the data. The default value is 0, indicating that polarization was not explicitly observed. Corresponding values are stored in the pol property

proposal_id¶: Identifier of proposal to which observation belongs

publisher_id¶: IVOA-ID for the Publisher. It will also be globally unique since each publisher has a unique registered publisher ID

s_calib_status¶: A string to encode the calibration status along the spatial axis (astrometry). Possible values could be {uncalibrated, raw, calibrated}

s_dec¶: CRS Declination of the center of the observation

s_fov¶: Approximate size of the covered region as the diameter of a containing circle. For most data products the value given should be large enough to include the entire area of the observation; coverage within the bounded region need not be complete, for example if the specified radius encompasses a rotated rectangular region. For observations which do not have a well-defined boundary, e.g. radio or high energy observations, a characteristic value should be given. The radius attribute provides a simple way to characterize and use (e.g. for discovery computations) the approximate spatial coverage of a data product. The spatial coverage of a data product can be more precisely specified using the region attribute.

s_pixel_scale¶: This corresponds to the sampling precision of the data along the spatial axis. It is stored as a real number corresponding to the spatial sampling period, i.e., the distance in world coordinates system units between two pixel centers. It may contain two values if the pixels are rectangular.

s_ra¶: ICRS Right Ascension of the center of the observation

s_region¶: Sky region covered by the data product (expressed in ICRS frame). It can be used to precisely specify the covered spatial region of a data product. It is often an exact, or almost exact, representation of the illumination region of a given observation defined in a standard way by the concept of Support in the Characterisation data model.

s_resolution¶: Spatial resolution of data specifies a reference value chosen by the data provider for the estimated spatial resolution of the data product in arcseconds. This refers to the smallest spatial feature in the observed signal that can be resolved. In cases where the spatial resolution varies across the field the best spatial resolution (smallest resolvable spatial feature) should be specified. In cases where the spatial frequency sampling of an observation is complex (e.g., interferometry) a typical value for spatial resolution estimate should be given; additional characterisation may be necessary to fully specify the spatial characteristics of the data.

s_resolution_max¶: Resolution max value on spatial axis (FHWM of PSF)

s_resolution_min¶: Resolution min value on spatial axis (FHWM of PSF)

s_stat_error¶: This parameter gives an estimate of the astrometric statistical error after the astrometric calibration phase.

s_ucd¶: UCD for the nature of the spatial axis (pos or u,v data)

s_unit¶: Unit used for spatial axis

s_xel1¶: Number of elements along the first spatial axis

s_xel2¶: Number of elements along the second spatial axis

t_calib_status¶: Type of time coordinate calibration. Possible values are principally {uncalibrated, calibrated, raw, relative}. This may be extended for specific time domain collections.

t_exptime¶

Total exposure time. For simple exposures, this is just the time_bounds: size expressed in seconds. For data where the detector is not active at all times (e.g. data products made by combining exposures taken at different times), the t_exptime will be smaller than the time_bounds interval. For data where the xptime is not constant over the entire data product, the median exposure time per pixel is a good way to characterize the typical value. In some cases, exptime is generally used as an indicator of the relative sensitivity (depth) within a single data collection (e.g. obs_collection); data providers should supply a suitable relative value when it is not feasible to define or compute the true exposure time.

In case of targeted observations, on the contrary the exposure time is often adjusted to achieve similar signal to noise ratio for different targets.

t_max¶: The stop time of the observation specified in MJD as an Time instance. In case of data products result of the combination of multiple frames, t_max must be the maximum of the stop times. None is used for NaN response values.

t_min¶: The start time of the observation specified in MJD as an Time instance. In case of data products result of the combination of multiple frames, min time must be the minimum of the start times. None is used for NaN response values.

t_ref_pos¶: Time Axis Reference Position as defined in STC REC, Section 4.4.1.1.1

t_resolution¶: Estimated or average value of the temporal resolution.

t_stat_error¶: Time coord statistical error on the time measurements in seconds

t_xel¶: Number of elements along the time axis

target_class¶: This field indicates the type of object that was pointed for this observation. It is a string with possible values defined in a special vocabulary set to be defined: list of object classes (or types) used by the SIMBAD database, NED or defined in another IVOA vocabulary.

target_name¶: The target_name attribute contains the name of the target of the observation, if any. This is typically the name of an astronomical object, but could be the name of a survey field. The target name is most useful for output, to identify the target of an observation to the user. In queries it is generally better to refer to astronomical objects by position, using a name resolver to convert the target name into a coordinate (when possible).

Navigation

ObsCoreRecord¶