The following table contains the Besselian elements for the Annular Solar Eclipse of 1977 Apr 18 .
The geographic coordinates of the eclipse path are in the Path Table . The global visibility of the eclipse is shown on an Orthographic Map . The features of this map are described in the Key to Solar Eclipse Path Tables. The path of the eclipse is displayed in greater detail on a Google Map .
Besselian Elements for the Annular Solar Eclipse of 1977 Apr 18
Equatorial Conjunction: 10:18:48.0 TDT J.D. = 2443251.929723
(Sun & Moon in R.A.) (=10:18:00.2 UT)
Ecliptic Conjunction: 10:36:13.6 TDT J.D. = 2443251.941824
(Sun & Moon in Ec. Lo.) (=10:35:25.8 UT)
Instant of 10:31:29.9 TDT J.D. = 2443251.938540
Greatest Eclipse: (=10:30:42.0 UT)
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Gamma = -0.3990 Ephemerides = VSOP87/ELP2000-82
Eclipse Magnitude = 0.9449 Lunation No. = -281
ΔT = 47.9 s Saros Series = 138 (29/70)
Lunar Radius k1 = 0.272488 (Penumbra) Shift in Δb = 0.00"
Constants: k2 = 0.272281 (Umbra) Lunar Position: Δl = 0.00"
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Geocentric Coordinates of Sun & Moon at Greatest Eclipse (VSOP87/ELP2000-82):
Sun: R.A. = 01h45m03.2s Moon: R.A. = 01h45m26.3s
Dec. =+10°51'37.3" Dec. =+10°30'41.9"
Semi-Diameter = 15'55.5" Semi-Diameter = 14'50.4"
Eq.Hor.Par. = 08.8" Eq.Hor.Par. = 0°54'28.0"
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Polynomial Besselian Elements for: 1977 Apr 18 11:00:00.0 TDT (=t0)
n x y d l1 l2 μ
0 0.338262 -0.321838 10.86803 0.566433 0.020194 345.16647
1 0.4926239 0.1332840 0.014200 0.0000499 0.0000497 15.003543
2 -0.0000041 -0.0000505 -0.000002 -0.0000100 -0.0000099
3 -0.0000057 -0.0000015
Tan ƒ1 = 0.0046565 Tan ƒ2 = 0.0046333
At time t1 (decimal hours), each Besselian element is evaluated by:
a = a0 + a1*t + a2*t^2 + a3*t^3 (or a = Σ [an*t^n]; n = 0 to 3)
where: a = x, y, d, l1, l2, or μ
t = t1 - t0 (decimal hours) and t0 = 11.000 TDT
The Besselian elements were derived from a least-squares fit to elements
calculated at five uniformly spaced times over a six hour period centered at t0.
The Besselian elements are valid over the period 8.00 ≤ t0 ≤ 14.00 TDT.
Note that all times are expressed in Terrestrial Dynamical Time (TDT).
Saros Series 138: Member 29 of 70 eclipses in series.
Predictions for the Annular Solar Eclipse of 1977 Apr 18 were generated using the VSOP87/ELP2000-82 solar and lunar ephemerides and a value of ΔT = 47.9 seconds. The accuracy of the northern and southern edges of the eclipse path are limited to approximately 1-2 kilometers due to the lunar limb profile.
All eclipse calculations are by Fred Espenak, and he assumes full responsibility for their accuracy. Permission is freely granted to reproduce this data when accompanied by an acknowledgment:
"Eclipse Predictions by Fred Espenak, NASA's GSFC"
For more information, see: NASA Copyright Information
