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DIAPHRAGM/ROMAFOT frame [regi_tab] [rego_tab] ap_rad

This command performs aperture photometry at given positions. These positions are read from a registration table created by REGISTER/ROMAFOT. Values of the sky background are read as well.

This command has two fairly different applications. The first application is fast photometry of many objects with the sequence of commands SKY/ROMAFOT, SEARCH/ROMAFOT, DIAPHRAGM/ROMAFOT. The second application is to calibrate a frame transporting standard magnitudes from another frame. Given the importance of a careful determination of the sky background, the previous use of FIT/ROMAFOT is not redundant in this second case. The user is allowed to select the diaphragm over which the integration is performed. Usually a compromise between large apertures (to sample all the stellar contribution) and small apertures (to minimise the light from nearby companions) is necessary.

This module creates an output file with the same structure as that created by FIT/ROMAFOT. However, the instrumental magnitude is determined by summing up the pixel intensities above the sky within the diaphragm.

Petra Nass