NAME

plband -- Plot synthetic and measured instrument passbands.

USAGE

plspec obsmode

DESCRIPTION

This task plots a synthetic passband by combining throughputs for telscope components, passbands read from files, and certain functional forms, such as a Gaussian or a rectangular window. The passband is specified by passing an expression in the obsmode parameter. The syntax for this expression is described in the help file for calcband.

The user can control certain plot attributes, such as the scaling and line type and append the plot to a previous plot genarated by plband.

PARAMETERS

obsmode [string]

The command used to create the synthetic passband. The command syntax is described in the help file for calcband. More than one passband can be plotted by placing the commands in a file, whose name is passed to this parameter, preceded by a "@" character, e.g., @filename. The keywords which make up the observing mode are explained further in the obsmode task.

(left = INDEF) [real]

Minimum wavelength to plot. If set to INDEF, the task will set it to the minimum wavelength in the wavelength set.

(right = INDEF) [real]

Maximum wavelength to plot. If set to INDEF, the task will set it to the maximum wavelength in the wavelength set.

(bottom = INDEF) [real]

Minimum passband value to plot. If set to INDEF, the task will set it to the minimum passband value.

(top = INDEF) [real]

Maximum passband value to plot. If set to INDEF, the task will set it to the maximum passband value.

(normalize = no) [boolean]

Normalize all passbands to a maximum value of 1? If normalize = no, each curve is plotted at its intrinsic level.

(ylog = no) [boolean]

Create a semilogarithmic plot?

(append = no) [boolean]

Append results to an existing plot?

(ltype = "solid") [string]

The line type to be used for plotting the mode1 passband. The allowed values are: clear, solid, dashed, dotted, and dotdash.

(device = "stdgraph") [string]

Send output to the designated device.

(wavetab = "") [file name]

Name of an optional wavelength table or file. An appropriate table can be generated by using the genwave task. If a table is used, the wavelength column name must be "WAVELENGTH". If an ASCII file is used the first column is taken to be the wavelength column. The subdirectory 'synphot$data has ASCII wavelength tables useful for specific HST passbands.

If no wavelength table is specified, a default wavelength set is used. The default wavelength table covers the wavelength range where the passband is non-zero. Wavelengths are spaced logarithmically over this range. If there is more than one passband, the range is computed based on the first passband. If the wavelength range of the spectra differ significantly, a wavelength table should be specified explicitly.

(refdata = "") [pset name]

Parameter set for reference data used in calculations. This pset contains the following parameters:

area = 45238.93416:  HST telescope area in cm**2.

grtbl = "mtab$*.tmg":  HST graph table.  By default, this
        uses the more recent version. 

cmptbl = "mtab$*.tmc":  Instrument component table.  By 
        default, this uses the more recent version.

EXAMPLES

1. Plot the WFPC,F555W passband as a solid line.

  sy> plband wfpc,f555w

2. Plot a modified Gaussian on a logarithmic scale as a dotted line. Set the minimum value to 1.e-5

  sy> plband "tilt(gauss(6000,1000),.1,.8,.2)" ltype=dotted bot=1.e-5 yl+ 

REFERENCES

Written by B.Simon based on XCAL code written by Keith Horne

SEE ALSO

calcband, plspec