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ANALYSE/ROMAFOT frame [cat_tab] [int_tab] [sigma,sat]

To examine the catalogue table created by the command FIND/ROMAFOT one should use the command ``M'' followed by the sequential position of the object. The commands ``W'', ``U'', ``6'', ``X'' and ``Y'' will set the display.

A subframe with the selected star at the center is presented to the user. This subframe can be reduced (or enlarged) by the command ``R'' followed by the decrement (or increment) in x and y: delta_x, delta_y, respectively.

The command ``S'', followed by the shift in x and y coordinate provokes the displacement of the window. ``R'' and ``S'' are useful to include or exclude stars in the subframe.

A ``bar'' allows the display of the current status of the window.

The intensity profiles are displayed with a scale which saturates at an intensity of $I \simeq 950$. This can be changed with the command ``B'' followed by a factor for the intensities, typically 0.1 or smaller.

In crowded fields the maps, isophotal contours and intensity profiles are not enough to visualize the situation. In this case the commands ``K'' and ``L'' may help. With ``K'' one gets the pixel coordinates (both absolute in the frame and relative in the window) and the pixel intensity at the cursor position. The command ``L'' gives the height (above the background) at the vertical cursor position.

If the window has been properly set, shaped and understood, the user is expected to position the cursor where he thinks a star exists and give the command ``I''. This command passes the trial position of the star and its height and will be repeated for all the stars in the window. The maximum number of objects allowed is 36, but the user is discouraged from approaching this limit for many reasons. The most simple one is that 36 stars (i.e. $36\times 3$ parameters) which are fitted separately in 36 subframes with N pixels each require $36 \times 3 \times N = 108 N$ calculations at each iteration: the same fit all together requires $36 \times 3 \times 36 \times N = 3888 N$ calculations.

The command ``J'' works like ``I'' with the difference that the user is expected to provide the trial value for the height: this can be useful in case of difficult convergence when e.g. several local minima exist in the parameter space.

If some unwanted feature is present in the window (cosmic rays, scratches, tails of other stars and so on) ``E'' is most useful. This command provokes a hole in the window whose radius will be given by the operator. The hole is centered at the cursor position and the pixels included within its area will be ignored in the subsequent calculations as far as this window is concerned. There is no effective limit to the number of holes $(\leq 50)$. For this reason, it is not practical to have hole positions reported on the screen (in fact, they could fill the whole screen). Therefore by default the holes will not be listed. To change that use the command ``-'' which enables the report hole positions and sizes. This command executes the inverse operation, as well.

During the examination of the objects passed by FIND/ROMAFOT it often happens that several stars are asked to fit together in the same window and some of these are in the catalogue table. In order not to repeat photometry of the same objects, ANALYSE/ROMAFOT flags in the catalogue table all the objects already considered and the user is supplied with the message ``object already considered''. It is possible to disable this feature with the key ``Z''.

The user may realize that the windows presented are too wide (or too narrow) depending on the telescope scale, seeing, crowding and so forth. In this case the command ``/'' can be used to change the default window size.

A minor feature is the key ``A''. This allows the default display of level contours (instead of colour maps) without using command ``X'' or ``Y''.

Finally, the command ``5'' selects the mode to examine the catalogue table, either to give the record (manual mode $\rightarrow$ ``M'') or running through the table (automatic mode $\rightarrow$ ``A''). It is possible also to examine the list selectively ( $\rightarrow$ ``S''). For instance all the objects above a given height threshold are disregarded by the command GROUP/ROMAFOT.

After execution of ANALYSE/ROMAFOT all the program stars are arranged with their trial values in (normally multiple) windows with selected dimensions and shapes: these data are stored in the intermediate table. To continue the user should now run the command FIT/ROMAFOT.

next up previous contents
Next: FIT/ROMAFOT Up: The Interactive Path Previous: FIND/ROMAFOT
Petra Nass