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Useful Procedures for Quick FOS Reduction

In May 1989, Andy Lawrence wrote a set of procedures to automate the TRIM, SPECTRUM, SPECPLOT and LEXPLOT routines which are used to reduce the FOS data at the telescope, so that a first order spectrum was produced in about the time it took to acquire the next object.

Because of ADAM niceties about character strings, and the fact that R1,S1,T1 etc. are psuedo-variables standing for the real file name,(e.g. R1 is SYS:FOSABC.001, where ABC is the observer's signon initials) it is not obvious how to put RUN numbers into procedures. The following (in which parameter names are arbitrary) will serve as a starting point.

To reduce the FIRST order spectrum from the raw image and output a 1D spectrum :-


a) Do not use previously defined ADAM variables (e.g. `in' and `out' are used by the COMPMIRROR command).

b) For well exposed spectra taken using the FOS dekker in position 1, (24 arc seconds, single aperture) TRIM will work well in the automatic mode, and find the dekker edge itself.

ADAM> put RED(Saves RED for next time).

You can reduce R1 and put the spectrum in S1 by typing:-


To plot the spectrum on the LEXIDATA and measure wavelengths on it, use the following procedure:-


a)5400 and 8000 in this line are the minimum and maximum wavelengths,which you can adjust to suit your requirements

b)SPECPLOT will insist on prompting for a title and comments, but will accept carriage return as null.

c)The scale should be about int(maxcounts/1000). Maximum counts are output to the screen by SPECTRUM (and hence by procedure RED).

You can invoke this with:-


In addition to the lexidata display, you can get a hard copy on the line printer.


a) Variable names must not be duplicated in your various procedures.

If you are feeling really ambitious, you can do everything from the raw image to the hardplot of the spectrum in one fell swoop.


a) The `0' is the scale for the plot, and is a way of overcoming not knowing the maximum counts from the start, and will force a prompt.

In tests with one object in the slit, and measuring one wavelength from the SPECPLOT stage, the procedure AUTO took fractionally under 2 minutes from starting, to returning to the ADAM prompt.

Run it by typing:-


Remember to answer the few remaining prompts!

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Tue Apr 12 04:13:28 BST 1994