nenupy.beamlet.bstdata

BST_Data

Object class BST_Data (from the beamlet module) inherits from Beamlet. It is designed to read the so called Beamformed Statistics Data or BST from the NenuFAR low-frequency radio-telescope.

Initialization

The BST_Data object needs to be provided with a path to a BST observation file (in FITS format):

>>> from nenupy.beamlet import BST_Data
>>> bst = BST_Data(
        bstfile='/path/to/BST.fits'
    )

Data selection

Data selection is enabled thanks to dedicated keywords that set BST_Data attributes. They can be set directly or passed as keyword arguments to BST_Data.select():

BST_Data.abeam: Analog beam index selection.
BST_Data.dbeam: Digital beam index selection.
BST_Data.polar: Polarization selection.
BST_Data.timerange: Time range selection.
BST_Data.freqrange: Frequency range selection.

>>> from nenupy.beamlet import BST_Data
>>> bst = BST_Data(
        bstfile='/path/to/BST.fits'
    )
>>> data = bst.select(
        timerange=['2020-01-01 12:00:00', '2020-01-01 13:00:00'],
        freqrange=[55, 65],
        polar='NW',
        dbeam=0
    )

Observation and current selection informations

Once initialized, a BST_Data contains many informations regarding the observation accessible via specific getters such as:

BST_Data.abeams: Available analog beal indices
BST_Data.dbeams: Available digital beam indices
BST_Data.mas: Mini-Arrays per per BST_Data.abeam
BST_Data.marot: Mini-Array rotations per BST_Data.abeam
BST_Data.ants: Antennas used per BST_Data.abeam
BST_Data.beamlets: Beamlet indices per BST_Data.dbeam
BST_Data.freqs: Available frequencies per BST_Data.dbeam
BST_Data.freq: Frequency selection
BST_Data.time: Time selection
BST_Data.azana: Azimuth pointed per BST_Data.abeam
BST_Data.elana: Elevation pointed per BST_Data.abeam
BST_Data.utana: Time range of analog pointings.
BST_Data.azdig: Azimuth pointed per BST_Data.dbeam
BST_Data.eldig: Elevation pointed per BST_Data.dbeam
BST_Data.utdig: Time range of digital pointings.

Other informations linked to the base class nenupy.beamlet.beamlet.Beamlet can also be accessed.

class nenupy.beamlet.bstdata.BST_Data(bstfile)[source]

Bases: Beamlet

Class to read NenuFAR BST data stored as FITS files.

Parameters:: bstfile (str) – Path to BST file.

property abeam

Analog beam index selected for the available beams (see BST_Data.abeams).

Setter:: Analog beam index
Getter:: Analog beam index
Type:: int

property abeams

Analog beam indices recorded during the observation. Each analog beam defines a particular set of Mini-Arrays as well as a given pointing direction.

Getter:: Analog beam indices available
Type:: numpy.ndarray

property ants

Antenna used within a Mini-Array. This is analog beam dependant (BST_Data.abeam).

Getter:: Antenna selected
Type:: numpy.ndarray

property azana

Pointed Azimuth for a given analog beam.

Getter:: Azimuth
Type:: astropy.units.Quantity

property azdig

Pointed Azimuth for a given digital beam.

Getter:: Azimuth
Type:: astropy.units.Quantity

property beamlets

Beamlet indices associated with a given digital beam (set with BST_Data.dbeam).

Getter:: Beamlet indices
Type:: numpy.ndarray

property bstfile

Path toward BST FITS file.

Setter:: BST file
Getter:: BST file
Type:: str
Example:

>>> from nenupy.beamlet import BST_Data
>>> bst = BST_Data(
        bstfile='/path/to/BST.fits'
    )
>>> bst.bstfile
'/path/to/BST.fits'

property dbeam

Digital beam index selected for the available beams (see BST_Data.dbeams).

Setter:: Digital beam index
Getter:: Digital beam index
Type:: int

property dbeams

Digital beam indices recorded during the observation. Each digital beam corresponds to a given pointing direction. They are also linked to corresponding BST_Data.abeams.

Getter:: Digital beam indices available
Type:: numpy.ndarray

property elana

Pointed Elevation for a given analog beam.

Getter:: Elevation
Type:: astropy.units.Quantity

property eldig

Pointed Elevation for a given digital beam.

Getter:: Elevation
Type:: astropy.units.Quantity

property freq

Current frequency selection made from setting BST_Data.freqrange.

Getter:: Frequency selection
Type:: astropy.units.Quantity

property freqrange

Frequency selection.

Setter:: Frequency range
Getter:: Frequency range
Type:: float, list, numpy.ndarray or astropy.units.Quantity
Example:

Set frequency to the closest available from 55 MHz:

>>> bst.freqrange = 55
>>> bst.freq
<Quantity [54.98047] MHz>

Select frequencies falling between two values: (assumed to be defined in MHz):

>>> bst.freqrange = [55, 56]
>>> bst.freq
<Quantity [55.17578 , 55.371094, 55.566406, 55.76172 , 55.95703 ] MHz>

or, using astropy.units.Quantity:

>>> import astropy.units as u
>>> import numpy as np
>>> bst.freqrange = np.array([55e6, 56e6]) * u.Hz
>>> bst.freq
<Quantity [55.17578 , 55.371094, 55.566406, 55.76172 , 55.95703 ] MHz>

property freqs

Recorded frequencies for a given digital beam (set with BST_Data.dbeam). Converted to mid sub-band frequencies

Getter:: Available frequencies
Type:: astropy.units.Quantity

property marot

Rotations corresponding to Mini-Arrays listed in BST_Data.mas.

Getter:: Mini-Arrays rotations
Type:: astropy.units.Quantity

property mas

Mini-Arrays that have been used for a given analog beam (set with BST_Data.abeam).

Getter:: Mini-Arrays selected
Type:: numpy.ndarray

property polar

Polarization selection (between 'NW' and 'NE').

Setter:: Polarization
Getter:: Polarization
Type:: str

select(**kwargs)[source]

Select data from the BST observation file.

Parameters:

freqrange (float, list, numpy.ndarray or astropy.units.Quantity, optional) – Frequency range (see BST_Data.freqrange).
timerange (str, list, numpy.ndarray or astropy.time.Time) – Time range (see BST_Data.timerange).
dbeam (int, optional) – Digital beam index (see BST_Data.dbeam)
polar (str, optional) – Polarization (see BST_Data.polar)

Returns:

Selected data

Return type:

nenupy.beamlet.sdata.SData

property time

Current time selection made from setting BST_Data.timerange.

Getter:: Time selection
Type:: astropy.time.Time

property timerange

Time selection.

Setter:: Time range
Getter:: Time range
Type:: str, list, numpy.ndarray or astropy.time.Time
Example:

Set time to the closest available from a given ISOT value:

>>> bst.timerange = '2019-11-29T15:00:00'
>>> bst.time
<Time object: scale='utc' format='jd' value=[2458817.125]>

Select times falling between two values:

>>> bst.timerange = ['2019-11-29T15:00:00', '2019-11-29T16:00:00']
>>> bst.time
<Time object: scale='utc' format='jd' value=[2458817.125 ... 2458817.16666667]>

or, using astropy.time.Time:

>>> from astropy.time import Time
>>> t0 = Time('2019-11-29T15:00:00')
>>> t1 = Time('2019-11-29T16:00:00')
>>> bst.timerange = [t0, t1]
>>> bst.time
<Time object: scale='utc' format='jd' value=[2458817.125 ... 2458817.16666667]>

or:

>>> from astropy.time import Time, TimeDelta
>>> t0 = Time('2019-11-29T15:00:00')
>>> t1 = t0 + TimeDelta(3600, format='sec')
>>> bst.timerange = [t0, t1]
>>> bst.time
<Time object: scale='utc' format='jd' value=[2458817.125 ... 2458817.16666667]>

property utana

This returns the time range of all pointings associated with a given BST_Data.abeam. The shape of the output array is:

[[pointing_1_start, pointing_1_stop], [pointing_2_start, pointing_2_stop], …]

Getter:: Time range of analog pointings.
Type:: astropy.time.Time

property utdig

This returns the time range of all pointings associated with a given BST_Data.dbeam. The shape of the output array is:

[[pointing_1_start, pointing_1_stop], [pointing_2_start, pointing_2_stop], …]

Getter:: Time range of digital pointings.
Type:: astropy.time.Time