Solar Eclipse Prime Page

Annular Solar Eclipse of 1977 Apr 18

Fred Espenak

Introduction


The Annular Solar Eclipse of 1977 Apr 18 is visible from the following geographic regions:

  • Partial Eclipse: Africa, south Asia
  • Annular Eclipse: Namibia, Angola, D. R. Congo, Zambia, Tanzania

The map to the right depicts the geographic regions of eclipse visibility. Click on the map to enlarge it. For an explanation of the features appearing in the map, see Key to Solar Eclipse Maps.

The instant of greatest eclipse takes place on 1977 Apr 18 at 10:31:30 TD (10:30:42 UT1). This is 3.1 days before the Moon reaches apogee. During the eclipse, the Sun is in the constellation Aries. The synodic month in which the eclipse takes place has a Brown Lunation Number of 672.

The eclipse belongs to Saros 138 and is number 29 of 70 eclipses in the series. All eclipses in this series occur at the Moon’s descending node. The Moon moves northward with respect to the node with each succeeding eclipse in the series and gamma increases.

The solar eclipse of 1977 Apr 18 is a relatively long annular eclipse with a duration at greatest eclipse of 07m04s. It has an eclipse magnitude of 0.9449.

The annular solar eclipse of 1977 Apr 18 is preceded two weeks earlier by a partial lunar eclipse on 1977 Apr 04.

These eclipses all take place during a single eclipse season.

The eclipse predictions are given in both Terrestrial Dynamical Time (TD) and Universal Time (UT1). The parameter ΔT is used to convert between these two times (i.e., UT1 = TD - ΔT). ΔT has a value of 47.9 seconds for this eclipse.

The following links provide maps and data for the eclipse.

The tables below contain detailed predictions and additional information on the Annular Solar Eclipse of 1977 Apr 18 .


Eclipse Data: Annular Solar Eclipse of 1977 Apr 18

Eclipse Characteristics
Parameter Value
Eclipse Magnitude 0.94492
Eclipse Obscuration 0.89288
Gamma-0.39903
Conjunction Times
Event Calendar Date & Time Julian Date
Greatest Eclipse 1977 Apr 18 at 10:31:29.9 TD (10:30:42.0 UT1) 2443251.937986
Ecliptic Conjunction 1977 Apr 18 at 10:36:13.6 TD (10:35:25.7 UT1) 2443251.941270
Equatorial Conjunction 1977 Apr 18 at 10:18:48.0 TD (10:18:00.2 UT1) 2443251.929169
Geocentric Coordinates of Sun and Moon
1977 Apr 18 at 10:31:29.9 TD (10:30:42.0 UT1)
Coordinate Sun Moon
Right Ascension01h45m03.2s01h45m26.3s
Declination+10°51'37.2"+10°30'41.9"
Semi-Diameter 15'55.5" 14'50.4"
Eq. Hor. Parallax 08.8" 0°54'28.0"
Geocentric Libration of Moon
Angle Value
l 2.6°
b 0.5°
c -22.4°
Prediction Paramaters
Paramater Value
Ephemerides JPL DE406
ΔT 47.9 s
k (penumbra) 0.2725076
k (umbra) 0.2722810
Saros Series 138 (29/70)

Explanation of Solar Eclipse Data Tables

Penumbral Shadow Contacts and Extremes: Annular Solar Eclipse of 1977 Apr 18

Contacts of Penumbral Shadow with Earth
Contact Event Contact Time
TD
Time
UT1
Latitude Longitude
First External ContactP107:33:32.807:32:45.029°30.1'S017°08.0'W
First Internal ContactP210:12:31.910:11:44.077°11.9'S005°31.6'W
Last Internal ContactP310:50:48.610:50:00.751°20.0'S093°27.1'E
Last External ContactP413:29:36.413:28:48.600°22.0'N067°41.7'E
Extreme Northern and Southern Path Limits of Penumbra
Contact Event Contact Time
TD
Time
UT1
Latitude Longitude
North Extreme Path Limit 1N108:41:37.808:40:49.905°35.9'S039°17.5'W
South Extreme Path Limit 1S110:00:29.709:59:41.979°07.5'S033°34.2'E
North Extreme Path Limit 2N212:21:16.712:20:28.924°18.5'N089°41.6'E
South Extreme Path Limit 2S211:02:59.211:02:11.358°38.1'S085°55.6'E

Explanation of Penumbral Shadow Contacts and Extremes Tables

Umbral Shadow Contacts and Extremes: Annular Solar Eclipse of 1977 Apr 18

Contacts of Umbral Shadow with Earth
Contact Event Contact Time
TD
Time
UT1
Latitude Longitude
First External ContactU108:41:17.908:40:30.137°35.3'S031°48.6'W
First Internal ContactU208:46:26.608:45:38.738°33.8'S032°47.5'W
Last Internal ContactU312:16:41.312:15:53.508°47.7'S084°09.1'E
Last External ContactU412:21:52.912:21:05.107°47.8'S083°02.9'E
Extreme Northern and Southern Path Limits of Umbra
Contact Event Contact Time
TD
Time
UT1
Latitude Longitude
North Extreme Path Limit 1N108:43:04.708:42:16.836°51.3'S032°28.7'W
South Extreme Path Limit 1S108:44:42.508:43:54.739°17.1'S032°07.6'W
North Extreme Path Limit 2N212:20:04.712:19:16.807°02.8'S083°38.8'E
South Extreme Path Limit 2S212:18:26.912:17:39.009°32.1'S083°33.9'E

Explanation of Umbral Shadow Contacts and Extremes Tables

Central Line Extremes and Duration: Annular Solar Eclipse of 1977 Apr 18

Extreme Limits of the Central Line
Contact Event Contact Time
TD
Time
UT1
Latitude Longitude
Extreme Central Line Limit 1C108:43:51.908:43:04.138°03.9'S032°18.2'W
Extreme Central Line Limit 2C212:19:17.412:18:29.608°17.1'S083°36.1'E

Explanation of Central Line Extremes Table

Greatest Eclipse and Greatest Duration
Event Time
TD
Time
UT1
Latitude Longitude Sun
Altitude
Sun
Azimuth
Path Width Central
Duration
Greatest Eclipse10:31:29.910:30:42.011°56.3'S028°04.6'E 66.4° 344.8° 220.4 km07m04.18s
Greatest Duration10:40:30.010:39:42.210°49.0'S030°21.5'E 66.0° 334.1° 222.6 km07m04.99s

Explanation of Greatest Eclipse and Greatest Duration

Polynomial Besselian Elements: Annular Solar Eclipse of 1977 Apr 18

Polynomial Besselian Elements
1977 Apr 18 at 11:00:00.0 TD (=t0)
n x y d l1 l2 μ
0 0.33826 -0.32184 10.8680 0.56645 0.02019 345.1664
1 0.49262 0.13328 0.0142 0.00005 0.00005 15.0035
2 -0.00000 -0.00005 -0.0000 -0.00001 -0.00001 -0.0000
3 -0.00001 -0.00000 - - - -
Tan ƒ1 0.0046565
Tan ƒ2 0.0046333

At time t1 (decimal hours), each besselian element is evaluated by:

x = x0 + x1*t + x2*t2 + x3*t3 (or x = Σ [xn*tn]; n = 0 to 3)

where: t = t1 - t0 (decimal hours) and t0 = 11.000

Explanation of Polynomial Besselian Elements

Links for the Annular Solar Eclipse of 1977 Apr 18

Links to Additional Solar Eclipse Information

Eclipse Predictions

Predictions for the Annular Solar Eclipse of 1977 Apr 18 were generated using the JPL DE406 solar and lunar ephemerides. The lunar coordinates were calculated with respect to the Moon's Center of Mass. The predictions are given in both Terrestrial Dynamical Time (TD) and Universal Time (UT1). The parameter ΔT is used to convert between these two times (i.e., UT1 = TD - ΔT). ΔT has a value of 47.9 seconds for this eclipse.

Acknowledgments

Some of the content on this website is based on the book Thousand Year Canon of Solar Eclipses 1501 to 2500. All eclipse calculations are by Fred Espenak, and he assumes full responsibility for their accuracy.

Permission is granted to reproduce eclipse data when accompanied by a link to this page and an acknowledgment:

"Eclipse Predictions by Fred Espenak, www.EclipseWise.com"

The use of diagrams and maps is permitted provided that they are NOT altered (except for re-sizing) and the embedded credit line is NOT removed or covered.