(25) Celestial Azimuth / Elevation (ARRL)
08-25-2023, 01:54 PM (This post was last modified: 08-25-2023 01:55 PM by SlideRule.)
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 SlideRule Senior Member Posts: 1,437 Joined: Dec 2013
(25) Celestial Azimuth / Elevation (ARRL)
An excerpt from the ARRL Handbook for radio amateurs, Azimuth and Elevation, 1991, page 23-37 & 23-38 {639-640}

" Calculator and Computer Programs
As has been mentioned, a calculator or computer may be used in solving the equations for azimuth and elevation. Tables in this section list suitable programs. The program of Table 9 is for Hewlett-Packard HP-25 and similar calculators using reverse Polish notation (RPN). With this program, the GHA and declination of a celestial body are entered for a particular time of day, and the calculator computes the azimuth and elevation for that time. Calculations must then be repeated for a different time of day, by using different GHA and declination values, as appropriate. For EME work, it is convenient to calculate ez-al data at 30-minute intervals or so, and to keep the results of all calculations handy during the EME window. Necessary antenna-position corrections can then be made periodically. "

Table 9
Calculator Program for Determining
Azimuth and Elevation of Celestial
Bodies

Code:
Line  Key Entry 01    RCL 1 02    - 03    STO 4 04    f COS 05    X↔Y 06    STO 5 07    f COS 08    × 09    RCL 0 10    f COS 11    STO 6 12    × 13    RCL 0 14    f SIN 15    STO 7 16    RCL 5 17    f SIN 18    STO 5 19    × 20    + 21    STO × 7 22    ENTER ↑ 23    g SINˉ¹ 24    f COS 25    STO × 6       use these program steps for the moon 26    g ¹⁄ₓ 27    X↔Y       use these program steps for the sun and distant bodies 26    f Last X 27    GTO 32 28    RCL 3 29    - 30    × 32    g TANˉ¹ 32    RCL 5 33    RCL 7 34    - 35    RCL 6 36    ÷ 37    g COSˉ¹ 39    RCL 4 39    f SIN 40    g X ≥ 0 41    GTO 44 42    R ↓ 43    GTO 00 44    R ↓ 45    CHS 46    RCL 2 47    + 48    GTO 00

" Instructions
1) Load the program, selecting lines 26 and 27 for either the moon or for more distant bodies. Switch to RUN.
2) Initialize: f PRGM; f FIX 1; g DEG
3) Store constants: 360 STO 2; 0.01657 STO 3
4) Store data:
your latitude (degrees and decimal; negative if east) STO 0
your longitude (degrees and decimal; negative if east) STO 1
5) Input data:
Decl. of celestial body (degrees and decimal) Enter ↑
GHA of celestial body (degrees and decimal) R/S
The result displayed after a few seconds is the azimuth or bearing in degrees clockwise from north.
Depressing X↔Y displays the elevation angle above the horizon. (The body is below the horizon if a negative angle is displayed.)
6) For another az-el calculation from the same location, go to step 5.
7) For az-el calculations from a different location on the earth's surface, go to step 4 using new latitude and longitude. "

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