Parameterise mode can be used to test the value of the optimum flux (that psf scale factor which best matches the data) at any point on the image. To invoke PSS in PARAM mode, specify the MODE keyword on the command line,
> PSS my_pss_demo 1.01 my_par_results mode=paramThe EXPERT and PSF prompts will appear as in the previous tutorial. The first different prompt is PLIST, which controls where PSS is to find source positions,
PLIST - Source of RA and DECs > MY_SOURCES 2 positions read from SSDS file MY_SOURCES...PSS can get positions from a number of sources (see below), one of which is a SSDS. If any of the positions read do not lie on the image, PSS will warn the user but continue.
The flux and significance are now evaluated at each test position, and the results printed.
Src RA DEC X Y Signif Flux
1 00 01 07.7 +00 10 04 16.93 10.07 10.101 96.441
2 23 59 59.8 +00 00 01 -0.04 0.01 27.499 354.031
Note that despite reading in positions directly from the previous PSS run, the values of flux and significance are different from those final results, by about 1% in flux. This is due to a slight difference in algorithm in the two modes. A time critical part of the error determination in SEARCH mode uses an approximation for the psf which can deviate from the true psf shape by a few percent. These discrepancies should be removed in the near future.
PSS can read in positions from various sources -- the source search results file (SSDS) mode is shown above. Positions can also be read from ascii text files. Each line should contain an RA and DEC specification separated by one or more spaces. The valid formats for such specifications are detailed Ref 5,`` User Interface,RA DEC Formats" topic.
The last alternative is to enter celestial positions manually. This can be
achieved in two ways. The first is using TT: as a file name. This
causes PSS to read lines from SYS$INPUT just as if they were read from
a text file (and so use CTRL-Z to terminate input),
PLIST - Source of RA and DECs > TT: 12h43m12.1s -34d56m 190.2 -35.012 2 positions read from ascii file TT:...The alternative is to supply
TERMINAL in response to the PLIST
parameter. The user is then repeatedly prompted for RA and DEC.
PLIST - Source of RA and DECs > TERMINAL Enter RA and DEC at prompts, ! to terminate RA - Right ascension /!/ > 12h43m12.1s DEC - Declination > -34d56m RA - Right ascension /!/ > 190.2 DEC - Declination > -35.012 RA - Right ascension /!/ > 2 positions read from TERMINAL...