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User Documentation |
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SUMMARY: fields | routine DETAILS: routine | ||||||||||
./guide gmeasure.pro
gmeasure |
procedure gmeasure, mode, fract, [brange=integer], [erange=integer], [rms=float], [/chan], [lefthorn=float], [righthorn=float], [/quiet], [ret=variable] |
Procedure to measure the area, width, and velocity of a galaxy profile.
The derived area, width and velocity are displayed unless the /quiet keyword is used. These values can also be returned using the ret keyword. The value of ret is a 6-element array containing the area, width, and velocity in that order estimates of the error on those quantities in the same order. The width and velocity are always given (shown and returned) in km/s and the area is given in data units * km/s. The error on the area is only set when fract equals 0.2 or 0.5. The errors on the width and velocity are only set for mode 4. Mode 4 always sets the width error to be twice the velocity error.
This is a front-end to awv. The source code there originated at Arecibo. See the comments there for a description of the 4 possibly values for mode and how fract and rms are used for each mode.
The data that is currently displayed in the plotter is used in this procedure. The displayed x-axis can be any type. The x-axis values are be converted to velocity taking into account any previously set velocity offset (even if the displayed axis is not the velocity axis). If there is no data displayed in the plotter, the contents of the primary data container (buffer 0) are used.
If the region of interest is not specified, the user is asked to mark it interactively.
A baseline should have been removed prior to using this function.
brange, erange, lefthorn, and righthorn are given in the currently display x-axis units unless the chan keyword is set.
Originally Contributed By: Karen O'Neil, NRAO-GB and Bob Garwood, NRAO-CV
gmeasure, 1, 0.5, ret=ret50 gmeasure, 1, 0.8, ret=ret80
Parameters | |
mode |
Must be one of 1,2,3, or 4. See the comments in awv for more details. |
fract |
Fraction of peak or mean used in locating the edges of the galaxy profile. See the comments in awv for more details. Note that in modes 3 and 4 the user is asked to mark the two horns of the galaxy profile with the cursor unless the optional lefthorn and righthorn keywords are used. |
Keywords | |
brange |
Starting value of the region of interest in x-axis units unless chan is set. |
erange |
Ending value of the region of interest in x-axis units unless chan is set. |
rms |
Used in modes 2, 3 and 4 as described in . If this is not supplied, it defaults to the stddev of the data within the region of interest given by brange and erange. |
chan |
Interpret the user supplied range and optional horn positions in channels instead of the current x-axis units. |
lefthorn |
Location of the left peak in x-axis units unless chan was specified. |
righthorn |
Location of the right peak in x-axis units unless chan was specified. |
quiet |
When set, the results are not printed to the terminal (the ret keyword should be used to get the results). |
ret |
Six-element array giving [area,width,velocity,areaerr,widtherr,velocityerr]. All six elements will be 0.0 if there was a problem. The areaerr is only set when fract is 0.2 or 0.5. The widtherr and velocityerr are only set by mode 4. Unset error values are 0.0. |