10-30-2019, 05:16 PM

MOON AZ-EL ROUTINE FOR HP45

Allowing for Parallax

(May also be used for Great Circle bearing and distance calculations)

G.D. Wall ZE2KV

"Moon Az-El Calculations

Preliminary:

(a) Longitude to STO 1 (degrees and decimals).

Longitude East positive, West negative.

(b) Colatitude for North elevated pole to STO 2 (degrees and decimals).

Colat for northern latitudes = 90 - Lat

Colat for southern latitudes = 90 + Lat

(c) Horizontal Parallax to STO 3 (degrees and decimals). Obtain from the Nautical Almanac

Routine:

Read in GHA (DMS)

DMS+

RCL 1

+ *Note if less than 360

COS

RCL 2

SIN

STO 4

×

90

ENTER Read in DEC (DMS} North positive South negative

DMS→

STO 5

SIN

×

RCL 2

COS

STO 6

RCL 5

COS

STO 5

×

+

ENTER

COS⁻¹

ENTER

(STO 8)

SIN

STO 7

RCL 3

×

+

CHS

90

+ Read Elevation

x⇄y

RCL 6

×

CHS

RCL 5

+

RCL 4

RCL 7

×

COS⁻¹ If less than 360 Read Azimuth otherwise proceed

CHS

360

+ Read Azimuth

At Test Point * less than 360 means values of 180 through

270 to 360, and negative values through -90 to -180

Test:

Location 36°-45'-40" N; 119°-47'-10" W

Horizontal Parallax 56.4'

GHA 85°-33.6'

Declination 13°-21.2' S

Read:

Elevation 29.61°

Azimuth 140.61°

Great Circle calculations:

1. Home station data is entered into STO 1 and STO 2 as before. STO 3 is zero.

2. Enter the longitude of the distant point at GHA but with

reversed sign, i.e., Long 120 W = 120 Long 50 E = -50

3. Enter the latitude of the distant point at DEC. Positive for North latitudes, negative for South.

4. Great Circle angular distance is stored at STO 8 for future use.

5. Bearing of the distant station is read at Azimuth.

6. Great Circle distance is then obtained:

RCL 8

69.057

× Read (in miles)

RCL 8

111.14

× Read (in kilometers)

7. Part of the parallax correction routine is not used in the Great Circle calculations and may be omitted. Miss out the steps (RCL 3 ..... .. Read Elevation x-y) but roll down twice after STO 7 and before RCL 6.

Test:

Fresno 36°-45'-40" N; 119°-47'-10" W

to Salisbury, Rhodesia

18°S; 31°E

Read:

Bearing 62.77° Distance 10235 miles"

BEST!

SlideRule

Allowing for Parallax

(May also be used for Great Circle bearing and distance calculations)

G.D. Wall ZE2KV

"Moon Az-El Calculations

Preliminary:

(a) Longitude to STO 1 (degrees and decimals).

Longitude East positive, West negative.

(b) Colatitude for North elevated pole to STO 2 (degrees and decimals).

Colat for northern latitudes = 90 - Lat

Colat for southern latitudes = 90 + Lat

(c) Horizontal Parallax to STO 3 (degrees and decimals). Obtain from the Nautical Almanac

Routine:

Read in GHA (DMS)

DMS+

RCL 1

+ *Note if less than 360

COS

RCL 2

SIN

STO 4

×

90

ENTER Read in DEC (DMS} North positive South negative

DMS→

STO 5

SIN

×

RCL 2

COS

STO 6

RCL 5

COS

STO 5

×

+

ENTER

COS⁻¹

ENTER

(STO 8)

SIN

STO 7

RCL 3

×

+

CHS

90

+ Read Elevation

x⇄y

RCL 6

×

CHS

RCL 5

+

RCL 4

RCL 7

×

COS⁻¹ If less than 360 Read Azimuth otherwise proceed

CHS

360

+ Read Azimuth

At Test Point * less than 360 means values of 180 through

270 to 360, and negative values through -90 to -180

Test:

Location 36°-45'-40" N; 119°-47'-10" W

Horizontal Parallax 56.4'

GHA 85°-33.6'

Declination 13°-21.2' S

Read:

Elevation 29.61°

Azimuth 140.61°

Great Circle calculations:

1. Home station data is entered into STO 1 and STO 2 as before. STO 3 is zero.

2. Enter the longitude of the distant point at GHA but with

reversed sign, i.e., Long 120 W = 120 Long 50 E = -50

3. Enter the latitude of the distant point at DEC. Positive for North latitudes, negative for South.

4. Great Circle angular distance is stored at STO 8 for future use.

5. Bearing of the distant station is read at Azimuth.

6. Great Circle distance is then obtained:

RCL 8

69.057

× Read (in miles)

RCL 8

111.14

× Read (in kilometers)

7. Part of the parallax correction routine is not used in the Great Circle calculations and may be omitted. Miss out the steps (RCL 3 ..... .. Read Elevation x-y) but roll down twice after STO 7 and before RCL 6.

Test:

Fresno 36°-45'-40" N; 119°-47'-10" W

to Salisbury, Rhodesia

18°S; 31°E

Read:

Bearing 62.77° Distance 10235 miles"

BEST!

SlideRule