sd - Tool

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5.1.1 sd - Tool

Single-dish data analysis package
Requires: Synopsis

Description

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.

reading: Scantable, Measurement Set, SDFITS (GBT, ATNF), NRO
writing: Scantable, Measurement Set, SDFITS (ATNF), image FITS, CLASS, ASCII

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.

Fitting

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.

Plotter

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.

Gridding

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.

Logging

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.

Methods

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_rcparameters	Print 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_model	Create 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

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