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Next: How to use ROMAFOT Up: Crowded Field Photometry Previous: Theory

   
Overview of ROMAFOT

The current MIDAS implementation of ROMAFOT consists of 17 commands which are listed in Table 5.3. In order to be able to execute these commands the context ROMAFOT should be enabled first. This can be done using the command SET/CONTEXT ROMAFOT.
 
Table 5.1: ROMAFOT commands
Command Description
ADAPT/ROMAFOT Adapt trial values to a new image frame
ADDSTAR/ROMAFOT Add pre-selected subarrays to the original image frame
ANALYSE/ROMAFOT Select objects or analyses the results of the fit procedure
CHECK/ROMAFOT Estimate number and accuracy of artificial objects recovered
CBASE/ROMAFOT Create the base-line for transformation of frame coordinates
CTRANS/ROMAFOT Execute transformation of coordinates on intermediate table
DIAPHRAGM/ROMAFOT Perform aperture photometry
EXAMINE/ROMAFOT Examine quality of the fitted objects; flags them if needed
FCLEAN/ROMAFOT Select subarrays containing artificial objects
FIND/ROMAFOT Select objects from ROMAFOT frame using the image display
FIT/ROMAFOT Determine characteristics of objects by non-linear fitting
GROUP/ROMAFOT Perform an automatic grouping of objects
MFIT/ROMAFOT Fit the PSF using the integral of the PSF (for undersampled data)
MODEL/ROMAFOT Determine subpixel values to be used for the integral of the PSF
REGISTER/ROMAFOT Compute absolute parameters and stores results in final table
RESIDUAL/ROMAFOT Compute difference between original and reconstructed image
SEARCH/ROMAFOT Perform actual search of object above certain threshold
SELECT/ROMAFOT Select objects or stores parameters in intermediate table
SKY/ROMAFOT Determine intensity histogram and background in selected areas
 

ROMAFOT is as interactive as the user wishes. In fact, during a reduction session the user is often asked to choose between an interactive or an automatic procedure, including ``greytone'' extremes. Hence, the package leaves it up to the user: For the user one cannot define a fixed set of guidelines for these decisions, apart from the two obvious considerations that no software can take the place of the human brain and that the benefit of photometric precision should be proportional to the cost in terms of human effort.

As stated above, apart from a part which has to be interactive, the user can choose between running ROMAFOT in automatic or in interactive mode. Hence, a number of interactive ROMAFOT commands have non-interactive ``sister'' command(s) with the same functionality. Figure 5.1 shows the flow diagram of the ROMAFOT package. From this diagram it is clear that after determining the PSF one can continue along two paths. Figure 5.2 visualises the procedure to insert artificial stars in the original frame in order to estimate the ability of the program to recover an object and the general reproducibility of the photometry. Finally, Figure 5.3 shows the procedure to use the photometric results (positions and intensities) from the frame with the best resolution as input for all the other program frames.

  
Figure 5.1: Romafot reduction scheme
\begin{figure}
\begin{center}
\begin{tabular}{\vert ccccc\vert c\vert}
\hline...
...DUAL/ROMAFOT & & & residuals\\
\hline
\end{tabular} \end{center} \end{figure}


  
Figure 5.2: Romafot procedure to determine accuracy and degree of completeness
\begin{figure}
\begin{center}
\begin{tabular}{\vert ccccc\vert c\vert}
\hline...
...\
& & CHECK/ROMAFOT & & & \\
\hline
\end{tabular} \end{center} \end{figure}


  
Figure 5.3: Romafot procedure to transfer inputs to other program frames
\begin{figure}
\begin{center}
\begin{tabular}{\vert ccccc\vert c\vert}
\hline...
... ANALYSE/ROMAFOT& & & check \\
\hline
\end{tabular} \end{center} \end{figure}

ROMAFOT is fully integrated into the MIDAS environment, which means that the image display part runs on all display system supported by MIDAS and that all intermediate and the final results are stores in MIDAS tables. Obviously, the use of the MIDAS table file system adds a great deal of flexibility to ROMAFOT, since a large number of MIDAS commands can be used (e.g. for table emanupulation, displaying, selection, etc.).


next up previous contents
Next: How to use ROMAFOT Up: Crowded Field Photometry Previous: Theory
http://www.eso.org/midas/midas-support.html
1999-06-15