Start of Document Contents Next Page


Qed is an outgrowth of the Quilt 9 photometer control and data acquisition program, and an earlier data reduction program called Dred, written by Butler Hine when he was a graduate student at Texas. Dred incorporated the idea of encoding and recording the keystrokes used to mark the data, which has been elaborated in Qed into recording all of the operations, and allowing playback to re-reduce raw data from that record. The display and most of the keystroke actions are taken from Quilt 9 directly, to avoid cognitive dissonance (brain damage) when going from Q9 to Qed. Dred did most of the same operations but used different keystrokes to effect them. Some of Qed's internal operations were lifted from Dred (e.g. division by a fitted polynomial function, correction to the barycenter of the solar system). Dred assumed that you knew what you were doing (Butler usually did) and did not check input parameters or keystroke sequences, so bad input or inappropriate keystrokes would often cause a crash, or wildly wrong output data. Qed is much less trusting than Dred was, insisting that input parameters fall within a defined range of values, and that the sequence of reduction steps follow a specific pattern. You can still crash the program if you know how, and get nonsense for output data if you demand it, but there is much less chance for inadvertant disaster.

Qed runs under MS-DOS on a PC, any version later than 2.0. It requires 640K of regular memory and, while it can run without floating-point hardware support, it is very slow when it does. All modern PCs have the hardware built in. It also requires a display screen driver, which you include by adding a command to your local config.sys startup file:

assuming the file nansi.sys is in the directory \systm. In addition to the file qed.exe you also need one called qed.tbl that lives in the same directory.

The basic purpose of the Qed program is to aid the observer in removing, to the extent possible, all of the non-astrophysical artifacts introduced into the measurements by the instrument, and by the telescope in its earth-based environment. It is the second in a sequence of programs designed to help astronomers do time-series photometry. The sequence reflects the way this is done: one must first acquire the data at the telescope, using a suitable photometer (program: Q9), reduce the data (Qed), analyze the data (Qmrg, Qsft), then interpret the data by fitting it to models of the astrophysical processes believed to be operating in the star (WDEC, WD-40).

Start of Document Contents Next Page