sd.scantable

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5.1.2 sd.scantable - Tool

Representation of single-dish data format
Description

The scantable is a representation of the Scantable, which is a data format designed properly for single-dish data. The scantable is implemented as CASA table so that it is possible to access data via table tool. On the other hand, the scantable has its own functions to get/set some data. In addition to the simple setter/getter and utility functions, the scantable has some data reduction function such as calibration, baseline fitting, etc.

The ’insitu’ option often appears in the functions. This parameter controls if a certain operation is applied to this scantable (true) or return another scantable that is a result of the operation (false). In former case, the original scantable loaded will be lost although the data on disk will be kept. The default value of the option depends on sd.rcParams dictionary. See sd.list_rcparameters for details about sd.rcParams.

The constructor takes several arguments that handles some of optional behavior of it. The getpt and antenna arguments are only effective if file specified by filename argument is Measurement Set format.

Definition

A documentation for detailed definition of the Scantable will be prepared by ATNF.

Arguments


Inputs
filename	Name of an input file, or a reference to an existing scantable (advanced)
	allowed:	string, scantable
	Default:
average	Average all integrations within a scan on read
	allowed:	bool
	Default:	None (taken from scantable.autoaverage attribute of rc parameters)
unit	Brightness unit. It must be consistent with K or Jy. It overrides the default value or replaces the value in existing scantables
	allowed:	string
	Default:	None
getpt	Measurement Set input data only. If True, all pointing data are filled.
	allowed:	bool
	Default:	False
antenna	Measurement Set input data only. Antenna selection by ID or name
	allowed:	string, integer
	Default:	” (first antenna in the ANTENNA table)
parallactify	Indicate that the data had been parallactified.
	allowed:	bool
	Default:	None (taken from scantable.parallactify attribute of rc parameters)

Example

# create scantable from the data from the second antenna in Measurement Set
s=sd.scantable(’sddata.ms’,average=False,getpt=True,antenna=1)

Methods

add	Return a scan where all spectra have the offset added
auto_cspline_baseline	Perform automatic line finding and baseline subtraction using cubic spline function
auto_poly_baseline	Perform automatic line finding and baseline subtraction using polynomial function
auto_sinusoid_baseline	Perform automatic line finding and baseline subtraction using sinusoidal function
auto_quotient	Automatic quotient for coordinated scans
average_beam	Average beams together for multi-beam observation
average_pol	Average polarizations together
average_time	Return time average of a scan
bin	Perform binning of spectra
chan2data	Return channel/frequency/velocity and spectral value
clip	Flag data by its spectral value
convert_flux	Return a scan where all spectra are converted to Jy or K
convert_pol	Convert data to a different polarization type
copy	Return a copy of this scantable
create_mask	Return a bool array based on [min,max] windows
cspline_baseline	Perform a baseline subtraction using cubic spline function
drop_scan	Return a new scantable where the specified scan number(s) dropped
flag	Apply FFT to the spectra
flag	Flag selected data using specified mask (channel based flag)
flag_nans	Flag NaN values

flag_row	Flag spectra based on specified rows (row based flag)
freq_align	Perform frequency alignment
freq_switch	Apply frequency switching to the data
gain_el	Apply gain-elevation correction based on user-provided data
get_abcissa	Get the abcissa values
get_antennaname	Get antenna name
get_azimuth	Get a list of azimuth during the observation
get_column_names	Get a list of column names in the main table
get_coordinate	Return the spectral coordinate for a given row as a coordinate object
get_direction	Get a list of positions on the sky as a string
get_directionval	Get a list of positions on the sky as a float
get_elevation	Get a list of elevation during the observation
get_fit	Get the stored fits for a row in scantable
get_fluxunit	Get a flux unit
get_inttime	Get a list of integration times for the observation
get_mask	Get mask for the specified row as a bool list
get_mask_indices	Compute a lists of mask start/end indices from the given bool array
get_masklist	Compute a list of mask windows from the given bool array
get_parangle	Get a list of parallactic angles for the observation
get_restfreqs	Get the rest frequency(s) stored in the scantable

get_rms	Calculate rms of the spectrum
get_row	Return a scantable with single row
get_row_selector	Return a selector object that only selects target row
get_scan	Return a specified scan(s) specified by scan number or source name
get_selection	Get current selection that is currently set on this scantable
get_sourcename	Get a list of source names for the observation
get_spectrum	Get the spectrum for the current row
get_time	Get a list of time stamps for the observation
get_tsys	Get a list of system temperatures
get_unit	Get the default unit of spectral axis
get_weather	Get the weather informations
getbeam	Get beam number of the given row
getbeamnos	Get a list of beam numbers in the scantable
getcycle	Get cycle number of the given row
getif	Get IF number of the given row
getifnos	Get a list of IF nubers in the scantable
getmolnos	Get a list of molecule ids in the scantable
getpol	Get polarization number of the given row
getpolnos	Get a list of polarization numbers in the scantable
getscan	Get scan number of the given row

getscannos	Get a list of scan numbers in the scantable
history	Print a history
invert_phase	Invert the phase of the complex polarization
lag_flag	Perform Fourier filtering on the spectra
mx_quotient	Form a quotient using ”off” beams when observing in ”MX” mode
nbeam	Return a number of beams
nchan	Return a number of channels
ncycle	Return a number of cycles
nif	Return a number of IFs
npol	Return a number of polarizations
nrow	Return a number of rows
nscan	Return a number of scans
opacity	Apply an opacity correction
parallactify	Set a flag to indicate the data should be treated as ”parallactified”
poltype	Get a polarization type
poly_baseline	Perform a baseline subtraction using polynomial function
recalc_azel	Recalculate azimuth and elevation for each sky position
resample	Perform a binning
rotate_linpolphase	Rotate a phase of the complex polarization
rotate_xyphase	Rotate a phase of the XY correlation

save	Store the scantable on disk
scale	Scale spectra by the given factor
set_dirframe	Set the frame type of the direction on the sky
set_doppler	Set definition of the Doppler correction
set_feedtype	Set the feed type
set_fluxunit	Set flux unit
set_freqframe	Set the frame type of the spectral axis
set_instrument	Set antenna name
set_restfreqs	Set rest frequency
set_selection	Select a subset of the data
set_sourcetype	Set the types of source to be source or reference scan
set_spectrum	Set spectrum for specified row
set_unit	Set unit for spectral axis
shift_refpix	Shift the reference pixel of the spectral coordinate
sinusoid_baseline	Perform a baseline subtraction using sinusoidal function
smooth	Smooth the spectra
stats	Compute specified statistics of the spectra
stddev	Compute standard deviation of the spectra
summary	Print a summary of the contents of the scantable
swap_linears	Swap the linear polarizations XX and YY

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