aa - Astronomical Almanac - Compiled for Cygwin

By WJR, Thu June 16 2022

Stephen L. Moshier's venerable aa program (an astronomical almanac used to calculate planet and star positions), compiled for Cygwin (gcc version 11.3.0). It can be used interactively, or input can be directed from a text file.

aa - Astronomical Almanac, version 5.6 (aa-5.6.tar.gz, 161K)

Example Usage

Used interactively, simply ./aa. Or with input directed from a file, ./aa < Mars-2022-06.txt. Sample input file Mars-2022-06.txt to display data for Mars in June, 2022. The second set of numbers, ending with -1, tells aa to quit.


Longitude, latitude, altitude, and other local parameters are specified in the aa.ini file. Note: this file must reside in the same directory as the aa executable.

-84.17 ;Terrestrial east longitude of observer, degrees
39.95  ;Geodetic latitude, degrees
252.0  ;Height above sea level, meters
10.0   ;Atmospheric temperature, deg C
1000.0 ;Atmospheric pressure, millibars
1      ; 0 - TDT=UT, 1 - input=TDT, 2 - input=UT
0.0    ;Use this deltaT (sec) if nonzero, else compute it.

Further Reading

Refer to the file included with the distribution.

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