# CubeSum_AT — Sums the emission in a cube.¶

This module defines the CubeSum_AT class.

class admit.at.CubeSum_AT.CubeSum_AT(**keyval)[source]

Creates a moment-0 map of a cube, with optional channel segment selection.

In optical astronomy this would be called a white light image. In radio astronomy it’s often called a Moment-0 map. CubeSum_AT is a special version of Moment_AT, mostly used to produce an unbiased reference line emission image, one that eliminates most of the (optionally frequency dependent) noise. Since it is not interested in the possibly many lines in the cube, it only adds up the emission. Higher order moments are thus meaningless. Use the LineID_AT/LineCube_AT/Moment_AT sequence to get meaningful higher order moments. This image is often used as a reference image to extract positions for CubeSpectrum_AT, or for PVSlice_AT to compute a best slice based on the moments of inertia in this map.

An optional CubeStats_BDP can be given, which will also contain the variation of the RMS accross the channels in this spectral window, from which one can judge if a channel based RMS clipping is really needed. In most cases this is not. NOTE: Currently channel based RMS clipping can be slow.

Also optionally a LineList_BDP (from LineSegment_AT or LineID_AT) can be added to the input, in which case you can select if the line segments are used to form an even better CubeSum. You can also select its complement, using linesum=False, in effect creating an image where only noise should be present (assuming the continuum had been subtracted properly). numsigma=0 is recommended in this case. This image is recommended to test your continuum subtraction strategy and should thus only contain noise and no obvious source structure.

Keywords

numsigma: float
The cutoff level for the moment map in terms of the characterictic noise, sigma. How sigma is determined, can be set via the sigma= keyword. Note that the values above numsigma*sigma and below -numsigma*sigma will be taken into the sum in order for this imagine to be unbiased, and for properly continuum subtracted cubes display absorbtion signal. Default: 2.0.
sigma: float
The noise level to be used for calculating the cutoff values. If a CubeStats_BDP is provided and sigma is provided negative, then CubeSum_AT uses the frequency-dependent sigma from the CubeStats_BDP used in the cutoff. This sigma was determined for each plane in the input cube. If a CubeStats_BDP is provided and sigma is provided positive, then the sigma is taken from its cube rms value and the actual value of sigma is ignored. If a CubeStats_BDP is not provided, sigma must be set to a positive value for masking. Otherwise, an exception will be thrown. A negative value is not allowed in this case. Default: -1.0. Units are those of the input image, typically Jy/beam.
linesum: boolean
Only used if a LineList_BDP is part of the input. In that case by default the line segments will be used to add to the Moment-0. If linesum=False, its complement (supposedly just noise) will be used. Default: True.
Extra channels added on either side of a line (as given by the LineList). Default: 5.
zoom: int
Image zoom ratio applied to the moment map plots. This does not affect the base (CASA) image itself. Default: 1.

Input BDPs

SpwCube_BDP: count: 1
Input spectral window cube; usually the output of an Ingest_AT.
CubeStats_BDP: count: 1 (optional)
Optional input for the global RMS or channel-based RMS (if sigma>0). Note that tracking channel-based RMS is currently very expensive. Normally the output of a CubeStats_AT.
LineList_BDP: count: 1 (optional)
Optional input of a LineList in case channels segments are selected or rejected to be included; usually the output of a LineID_AT. A LineSegment_BDP (from LineSegment_AT) is also allowed.

Output BDPs

Moment_BDP: count: 1
Graphics Produced
TBD
Parameters: keyval : dictionary, optional

Attributes

 _version (string)

Methods

 addinput(item[, slot]) Add a BDP input to an AT. addinputbdp(item[, slot, insert]) Add a BDP to the _bdp_in list. addoutput(item[, slot]) Add a BDP output product to an AT. addoutputbdp(item[, slot, insert]) Add a BDP to the _bdp_out list. baseDir([path]) Get/set project base directory. bestMatch(at1, at2) Determines the better match of two tasks to the current one. checkfiles() Check if the files from all the BDP_out’s in an AT exist. checktype(item) Check the type of an object to see if it is a BDP. clearinput() Clear the input BDP list. clearoutput([delete]) Clear the output BDP list. copy() Creates an independent duplicate of the task. delete() Method to delete the AT and underlying BDPs. delinput(slot) Delete a specific BDP in the _bdp_in list. deloutput(slot) Delete a specific BDP in the _bdp_out list. dir([filename]) Absolute directory reference of the ADMIT project. dryrun() Method to do a dry run of the AT, generally just checks input values for errors. enabled([state]) Returns current task enabled setting, with optional reset. execute([args]) Executes the task. freeAlias(aliases[, alias]) Deletes alias reservation, if present. get(attrib) Method to get the given attributes value getProject() Retrieves project ID associated with the task. getVersion() Return the version string. getdtd(fl) Method to write out the dtd data. geteffectivelevel() Method to get the effective logging level of the logging subsystem getkey(key) Retrieval value for a key. getloggername() Method to get the name of the logger for this AT instance getlogginglevel() Method to get the current logging level of the AT haskey(key) Query if a key exists for an AT. html(inheader) Method to represent the current AT in HTML format. id([strip]) Returns task ID number. isAutoAlias([withEmpty, compat]) Whether the task alias appears to be auto-generated. isequal(at) Method to determine if two ATs are the same. isstale() Returns whether the AT is out of date. len2() Returns the length of _bdp_in and _bdp_out in a tuple. link() Increments the task link count. markChanged() Mark an AT that it’s state was changed, so it would need to be rerun. markUpToDate() Resets _stale to indicate that the AT does not need to be run. merge(at[, aliases]) Merges attributes from another task. mkdir(dirname) Make a directory in the ADMIT hierarchy. mkext(filename, ext[, alias]) Return a new filename with a new extension with optional ADMIT alias. newId(tid) Assigns the task a new ID number. reset(a) Performs an in-place shallow copy. run() The run method creates the BDP running([state]) Returns current task execution flag, with optional reset. save() Save (write) any BDPs connected to this AT. set(item, val) Method to set protected attributes, rather than direct access setAlias(aliases[, alias, auto]) Sets and registers the task alias, guaranteed unique among registered aliases. setProject(pid) Adds a project ID to task ID. set_bdp_in([bdpin]) Validate the _valid_bdp_in list and digest it into the appropriate attributes. set_bdp_out([bout]) Validate the _valid_bdp_out list and digest it into the appropriate attributes. seteffectivelevel(level) Method to set the effective logging level of the logging subsystem setkey([name, value, isinit]) Set keyword value. setloggername(name) Method to set the name of the logger for this AT instance setlogginglevel(level) Method to set the logging level show() Return the AT type. statusicons() return some html icons representing the enabled/stale status of this task summary() Returns the summary dictionary from the AT, for merging into the ADMIT Summary object. unlink() Decrements the task link count. userdata() Returns the user dictionary from the AT, for merging into the ADMIT userdata object. validateinput([describe]) Method to validate the _bdp_in’s against a dictionary of expected types. validatekeys() Method to error check all input keys. write(node) Method to write the AT to disk.
run()[source]

The run method creates the BDP

Parameters: None None
summary()[source]

Returns the summary dictionary from the AT, for merging into the ADMIT Summary object.