Declination Angle Chart 
(dish size list or tuning page)
(to Western Hemisphere,Eastern Hemisphere,Footprints by Dish Size)

 
Explanation of Declination
Declination angle keeps satellite antenna from
aiming into deep space and changes value with
latitude in accordance to earth's curvature.

    Early
    astronomers developed the 

    polar mount to track stars. For deep 

    space tracking, i.e. star observation, 

    the elevation setting of the polar mount 

    is equal to the latitude of the site 

    location. However, geostationary 

    satellites are much closer to earth than are celestrial objects
    and their observation requires a slight tilting 'downwards' from
    deep space 

    observation settings to see the geostationary satellite arc.
    This adjustment of (to) the polar mount, the tilting downwards,
    is the declination adjustment of the polar mount and its amount
    is the declination offset angle (not to be confused with the
    declination angle which is the sum of the declination offset
    angle and the polar axis zenith elevation angle). The declination
    angle is determined by the formula below where 22300 is the distance
    from the surface of the earth to the satellite belt and 3964
    is the radius of the earth (both in km.). In summary, the declination
    angle lowers the satellite antenna from looking into deep space
    to look at the arc of geostationary satellites. However, upon
    practice, it has been discovered that using the latitude as the
    elevation angle, (first chart below),
    the satellites at the top of the arc, in a tracking mount system,
    were in perfect alignment with the satellite dish, i.e. were
    tracked perfectly by the polar mount, whereas the satellites
    at the lower ends of the arc where not tracking correctly. Conversely,
    if the satellites at the ends of the arc, on the horizon, were
    tracking correctly then the central satellites, at the top of
    the arc would be slightly off target. This effect is caused by
    the slight deviation from the true north/south line, caused by
    the act of the tilting of the dish, as the dish moves to view
    satellites lower on the arc, i.e. closer to the horizon. With
    this in mind, it was formulated the elevation/declination angles
    of the modified polar mount (second chart
    below) whose application has no effect on seeing satellites
    at the top of the arc but has the effect of better tracking on
    the sides and low end of the arc. This effect is accomplished
    by slightly increasing the elevation angle and accordingly slightly
    decreasing the declination angle by the same amount. Use elevation/declination
    settings from the modified polar mount
    chart (second chart below) when installing and adjusting
    your polar mount tracking system - compare the values of the
    two charts below to see the difference in elevation and declination
    angles. Note: Elevation and declination angles are always
    measured and applied when the dish is at its zenith, i.e. highest
    point in the arc, when the dish axis is aligned along the true
    north-south line. (Applying
    declination/elevation angles.)
 

    Declination angle for normal mounts may be found by using the
    following equation:

    ARCTAN((3964*SIN(L)/(22300+3964(1-COS(L)))))

    Where 'L' is your site latitude.

    NOTE: This formula does not yield modified polar mount
    declination values but yields the values in the chart immediately
    below.

Declination Angle Chart
NOTE: This table is for traditional polar mount adjustment where elevation angle=latitude;
for modified polar mount declination values see second chart below.

Latitude (deg)	Declination Angle (deg)	Latitude (deg)	Declination Angle (deg)	Latitude (deg)	Declination Angle (deg)	Latitude (deg)	Declination Angle (deg)
1	0.18	24	4.07	46	6.92	69	8.47
2	0.36	25	4.23	47	7.01	70	8.51
3	0.53	26	4.38	48	7.11	71	8.54
4	0.71	27	4.53	49	7.21	72	8.56
5	0.89	28	4.67	50	7.30	73	8.59
6	1.06	29	4.82	51	7.38	74	8.61
7	1.24	30	4.96	52	7.47	75	8.63
8	1.41	31	5.10	53	7.55	76	8.64
9	1.59	32	5.24	54	7.63	77	8.66
10	1.76	33	5.38	55	7.71	78	8.67
11	1.94	34	5.51	56	7.78	79	8.67
12	2.11	35	5.64	57	7.85	80	8.68
13	2.28	36	5.77	58	7.92	81	8.68
14	2.45	37	5.90	59	7.99	82	8.68
15	2.62	38	6.02	60	8.05	83	8.68
16	2.79	39	6.14	61	8.11	84	8.67
17	2.95	40	6.26	62	8.16	85	8.66
18	3.12	41	6.38	63	8.22	86	8.65
19	3.28	42	6.49	64	8.27	87	8.64
20	3.44	43	6.60	65	8.31	88	8.62
21	3.60	44	6.71	66	8.36	89	8.60
22	3.76	45	6.81	67	8.40	90	8.58
23	3.92	68	8.44

Modified Polar Mount Tracking Angles
NOTE: Elevation Angle is the angle measured on (at) the pivot axis of the mount. To get the Total Declination Angle setting as measured on (at) the back of the dish ring (dish mount), add the Declination Offset Angle to the Elevation Angle. In summary, the difference between the Total Declination Angle and the Elevation Angle is the Declination Offset Angle. Elevation and Declination Angles are always measured and applied when the dish is at its zenith, i.e. highest point in the arc, when the dish axis is aligned along the true north-south line.