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Inspecting data

FIND-CENTROID Find the centroid of emission for X-register spectrum
FIND-INTEGRATED-INTENSITY Determine integ'd intensity in nominated range
FIND-LINE-WIDTH Interactive measurement of line equivalent width
FIND-MAXIMUM Find the position of the maximum in the spectrum
FIND-MOMENTS Calculates the moments of the spectrum outside line core
FIND-SKEWNESS Calculate higher order moments
FIND-SPECTRUM-STATISTICS Determine mean, std deviation and Tsys for spectrum
FIND-ZENITH-DISTANCE Work out Zenith distance (complementary Elev'n) of obs'n
LIST-SPECTRUM Write the current data to current list file
PRINT-SPECTRUM-HEADER Write the current header to current list file

Several parameters of the spectrum (or line, if any) can be measured. FIND-SPECTRUM-STATISTICS returns the mean and standard deviation of all the points within the selected baseline regions (which may be chosen using the graphics crosshairs in interactive mode, or input as numbers directly). FIND-INTEGRATED-INTENSIT(y) calculates the total emission or absorption between user-defined limits (which are defined using the graphics crosshair if plotting on a graphics terminal). FIND-MAXIMUM calculates the value and position of the maximum of the current spectrum, using a crude interpolation algorithm. FIND-MOMENTS and FIND-SKEWNESS are both useful for the calculation of various moments of the spectrum -- FIND-MOMENTS about a defined point, and FIND-SKEWNESS about the centroid. FIND-CENTROID returns the mean position and I will change the command name as soon as I can. FIND-LINE-WIDTH evaluates the equivalent width (i.e. integrated intensity divided by maximum intensity) in a window selected using the cursor (or directly if not using interactive graphics).

FIND-ZENITH-DISTANCE evaluates the zenith distance (90-deg - Elevation) for the date/time and RA/Dec in the scan header, and resets the value in the header in cases where the latter is in error. As for evaluating the LSR velocity, the telescope site must be defined for this to work -- use SET-SITE-PARAMETERS.

The current spectrum header can be printed on the current list device (the terminal or printer, depending on what is set up by SET-LIST-FILE) using PRINT-SPECTRUM-HEADER, while the data values can be listed using LIST-SPECTRUM.


next up previous contents
Next: Plotting data Up: OUTLINE OF FACILITIES Previous: Scan arithmetic   Contents
Jamie Leech 2004-08-16