This package contains software which analyzes a set of measurements of many stars taken from many images. It tries to find the optimal photometric solution, allowing the zero-point of each image to float to the level which brings the stars into the best agreement.
The idea behind this "inhomogeneous ensemble photometry" is described very clearly in a paper by R. Kent Honeycutt, CCD ensemble photometry on an inhomogeneous set of exposures", in Publications of the Astronomical Society of the Pacific, volume 104, page 435 (1992).
The software is written in ANSI C. The latest versions requires the GNU Scientific Library (GSL) to do much of the least-squares minimization. The oldest versions (0.1, 0.2) do not require the GSL, but are fragile. The selftest script is written in Perl; it works with Perl 5.
The current version is ensemble 1.2, last modified Jun 15, 2019. It includes a new option, "quick=", which can speed up execution in datasets with many faint stars. You must install the GNU Scientific Library to build this version.
Older versions:
Last modified Jun 15, 2019 by Michael Richmond