DAOPHOT is invoked by the simple command:
this should generate a response similar to:
Subsequent use of daophot will place you inside the DAOPHOT executable image, which you can
leave with the command:
Inside the executable image you can identify the data to be analysed by DAOPHOT using the command:
The file has to be in the NDF format of the Starlink Standard Data Structures (SUN/33). The default
file extension is .sdf.
At present DAOPHOT can only handle NDF files that have the DATA_ARRAY structure at the top level. If the program fails to find the data structure in the container file, then the message:
will be displayed. If you do not expect this message, then this is the moment to seek help from your system manager. If you do not get this message, then you can carry on with DAOPHOT.
The complete set of DAOPHOT commands can be found in the user’s manual (MUD/9).
There are three options files which are used by DAOPHOT at various stages of the reduction. There
are examples of these in the directory specified by the DAOPHOT_DIR environmental variable. The
file daophot.opt is used when the program starts up. Parameter definitions can be added or
removed from the options file as required. An option is specified using a two letter mnemonic
followed by its value. If a copy of this file is not present in the default directory, or the
parameters have invalid values, then the program will prompt for those parameters that it
cannot continue without, namely the read-out noise and the gain. This is signified by the
message:
followed by the parameter prompt. The user has to give values for the read-out noise and gain before the program will continue. Both parameters are used at various stages of processing and the user guide keeps stressing that it is highly advisable to have the most accurate values as possible for these parameters. Although the program will execute with guesstimates for these, the results should be treated with caution. The sections on the PEAK and NSTAR commands in the user guide suggest a method of checking the validity of the values given.
The file photo.opt contains the list of aperture radii used by DAOPHOT when performing aperture
photometry.
An alternative to the iterative profile fitting routine NSTAR in DAOPHOT has been written by Peter Stetson and is called ALLSTAR. It is described in the user manual and can be executed by typing:
The file allstar.opt contains parameters for this program.