Introduction

This chapter describes the set of commands implemented in MIDAS to do crowded field photometry on digital astronomical images. The package has been developed by
R. Buonanno, G. Buscema, C. Corsi, I. Ferraro, and G. Iannicola, all at the Osservatorio Astronomico di Roma. The package runs as a part of the data reduction system at Rome Observatory and is well known from its name: ROMAFOT. Since in Italian the suffix ``fot'' refers also to the word ``photometry'', the name ROMAFOT was chosen as an easy homophony with DAOPHOT.

The idea of ROMAFOT was born (and realised) in the second half of the seventies. The need for such a package has arisen from the technical evolution (for instance the arrival of the PDS etc.) and from the huge amounts of data becoming manageable. A rich bibliography of authors who worked on the same objective (e.g. Newell and O'Neil, 1974 [1], Van Altena and Auer, 1975 [2], Butcher, 1977 [3], Herzog and Illingworth, 1977 [4], Chiu, 1977 [5], Auer and Van Altena, 1978 [6] Buonanno et al., 1979 [7], Buonanno et al., 1983 [8] Stetson, 1979 [9], Stetson, 1979 [10]) shows that efficient handling of digital astronomical images was widely felt for the astronomical community. In addition, since the numerical problem requires very classic solutions, neither the idea nor the solution asks for particular emphasis.
Where ROMAFOT has perhaps merit is in having taken dozens of decisions such as:

• should the sky background be calculated before or together with the star?
• which size of the subwindow optimises the ratio photometric quality/computing time?
• when should two objects be considered blended and be fitted together?
• which is the optimum degree of interaction?

All these choices require experiments, time, and naturally effort.

In this description Section 5.2 gives some theoretical background about how ROMAFOT operates. Section 5.3 presents an overview of the commands available in the ROMAFOT context. Section 5.4 describes the commands in detail. The section is split into a part for the automatic reduction and a part for the more interactive reduction. Finally, Section 5.5 gives a summary of all ROMAFOT commands.