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5.1.1 sd - Tool

Single-dish data analysis package
Requires: Synopsis


The sd tool provides data reduction functions for single-dish (auto-correlation) data. It is actually a standalone software that is called ASAP (ATNF Spectral Analysis Package). For more information about ASAP, visit here.

The sd tool is a top level object and it contains various sub tools as well as a number of functions.

Important note

In the latest release, single dish package is loaded at the start-up of CASA. Therefore, it is not necessary to load ASAP explicitly anymore.

Data format

There are various types of data format for single-dish data. Currently, sd tool supports the following data formats for reading and writing.

An internal data format for sd tool is Scantable. The Scantable is defined as CASA table and is specially designed for single-dish data. The data is converted to Scantable during the processing whatever its original data format is. The result of the processing can be stored in other data format than Scantable. The Scantable is implemented as sd.scantable object in sd tool. See sd.scantable for details.

Selecting data

The Scantable can contain data with various types of frequency setting, multiple polarization components, and so on. In case you want to select data by some conditions, sd.selector is available for that. The sd.selector provides various functions to select and/or to sort data as well as it provides an interface to select data by TaQL. See sd.selector for details.


The sd.fitter is an object to perform fitting data. Both baseline and line fitting for spectral data can be done by this object if appropriate fitting function and masked region are set. Currently, Gaussian and Lorentzian are supported for line fitting, while polynomials with arbitrary order are available for baseline fitting. Masking should be applied in the form of Bool array. See sd.fitter for details.

Line finding

The sd tool provides automatic line finding functionality that is called sd.linefinder. The sd.linefinder has a few control parameter for line finding. The user is able to customize a behavior of line finding process by changing these parameters. Simplified line finding tool sd.simplelinefinder is also available. See sd.linefinder and sd.simplelinefinder for details.

Line catalog

The sd.linecatalog object is an interface for line catalog. The input data should be provided from the user. Supported format is ASCII table or specific format for sd.linecatalog. CASA package contains a default line catalog that is a part of JPL line catalog and is specific table format for the sd tool (ASAP). Benefit of this object is that it provides an interface to the catalog such as selecting lines by frequency and/or line intensity. It also enables an interaction between spectral data on the sd.plotter such as overlaying line catalog on the plotted spectra. See sd.linecatalog for details.


The sd.plotter is a plotter object that is exclusively designed for sd tool. That provides plotting functionalities for spectral data, time variation of azimuth and elevation, and pointing information. For plotting spectral data, it supports multi-panel and multi-page plot. See sd.plotter for details.

Coordinate system

The sd.coordinate is a representation of spectral coordinate of the data (frequency axis). It provides functions for conversion between pixel (channel), frequency, and velocity. See sd.coordinate for details.

Opacity model

In the sd tool, MIRIAD like atmospheric opacity model is implemented as sd.opacity_model. It calculates opacities from given atmospheric conditions (temperature, pressure, and humidity) and elevation. See sd.opacity_model for details.


The tool to convolve spectral data onto regularly spaced grid, sd.asapgrid is available. Currently, three convolution kernels, box, prolate-spheroidal, and gaussian, can be used for convolution. See sd.asapgrid for details.


Although logging system is integrated into CASA logger, sd tool has own logging functions so that you can use it instead of CASA logging functions. Log messages will be displayed in the CASA logger either you use logging functions for CASA or sd tool. See sd.asaplog for details.


almacal Calibration function specific for ALMA data
apexcal Calibration function specific for APEX data
average_time Averaging data in time
calfs Calibration function for frequency switched data
calibrate High level function for calibration
calnod Calibration function for nodding data
calps Calibration function for position switched data
commands Show a list of commands and their short descriptions
dosigref Equivalent function with dosigref in GBTIDL
dototalpower Equivalent function with dototalpower in GBTIDL
fitter Create a fitter object
get_revision Get revision of the source code for the tool
is_asap_cli Return True if the tool is launched as standalone software
is_casapy Return True if the tool is loaded as part of CASA
linecatalog Create a linecatalog object
linefinder Create a linefinder object
list_files Return a list of files readable by sd tool
list_rcparametersPrint a list of rc parameters
list_scans Return a list of scantables created by the user
mask_and Logical operation function on array
mask_or Logical operation function on array
mask_not Logical operation function on array
merge Merge a list of scantables into one
opacity_modelCreate a opacity_model object
quotient Take a quotient of a signal and reference scan
rc Set the current rc parameters
scantable Create scantable object
selector Create selector object
skydip Determine the opacity from a set of ’skydip’ observations
splitant Split Measurement Set data by antenna and save them as scantable
unique Return the unique values in a list
welcome Return a welcome message

    sd.almacal - Function
    sd.apexcal - Function
    sd.average_time - Function
    sd.calfs - Function
    sd.calibrate - Function
    sd.calnod - Function
    sd.calps - Function
    sd.commands - Function
    sd.dosigref - Function
    sd.dototalpower - Function
    sd.get_revision - Function
    sd.is_asap_cli - Function
    sd.is_casapy - Function
    sd.list_files - Function
    sd.list_rcparameters - Function
    sd.list_scans - Function
    sd.mask_and - Function
    sd.mask_or - Function
    sd.mask_not - Function
    sd.merge - Function
    sd.quotient - Function
    sd.rc - Function
    sd.skydip - Function
    sd.splitant - Function
    sd.unique - Function
    sd.welcome - Function

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