The Total Solar Eclipse of 11 June 1983. The dark blue region is the path of totality (also known as the umbra).
The umbra shadow travels from west to east (left to right on the map). At the point of greatest eclipse, totality is at local midday. The duration of totality at greatest eclipse is 5 minutes 11 seconds. This occurs just north of the island of Java in Indonesia. On either side of that point, the duration is less. To the West of greatest eclipse the eclipse will be total before local noon; to the east, the eclipse will be total after local noon. The umbra is widest around the time of greatest eclipse as the Earth is bulging out towards the Moon in that region.
The blue circlular regions are the positions of the umbra at ten minute intervals. The umbra becomes more circular around the region of greatest eclipse as the surface of the Earth is at its most perpendicular to the umbra. The sub-solar point is the location where the Sun is overhead at the time of greatest eclipse. This point is well north of the equator at this time of year (June).
The red regions are the areas where the eclipse occurs during sunrise (left) or sunset (right). The area on either side of the path of totality (in pale blue) provides a partial eclipse, the magnitude decreasing with distance from the path of totality. Beyond the blue lines, no eclipse is visible.
The path of totality begins in the southern Indian Ocean, crossing the islands of Java, Sulawesi and New Guinea and leaving the Earth in the Pacific Ocean north of New Zealand. The umbra takes 3 hours 1 minute to traverse its entire path.
Our eclipse site was on the northern coast of the island of Java where the eclipse occurs just before local noon.
| Location | Tuban, Northern Java, Indonesia |
| Altitude | 2 m |
| Distance from Centre Line | < 1 km |
| 1st Contact (UT + 7) | 09:58 |
| 2nd Contact | 11:32 |
| 3rd Contact | 11:37 |
| 4th Contact | |
| Duration | 5m 10s |
| Path Width | 199 km |
| Solar Altitude | 60° |
| Solar Azimuth | 350° |
| Saros Details | 127 (56 / 82) |
| Gamma | -0.4949 |
| Diameter Ratio | 1.052 |
The Distance from Centre Line was estimated using a map with the path of totality plotted from Fred Espenak data.
First Contact is the beginning of the eclipse when the first "bite" appears on the Sun's disk; it is the beginning of the partial phase. Second Contact is the beginning of totality. Third Contact is the end of totality. Fourth Contact is the end of the partial eclipse - by that time we had packed up and left. The times are in local time which, for this eclipse, is UT + 7 (GMT plus seven hours).
The Duration of the eclipse at the observation site was 5 minutes 10 seconds.
The Path Width is the width of the path of totality. The value for this eclipse was 199km. This was a reasonably large figure that produced a long eclipse.
The Sun's Altitude is measured from the horizon; the Azimuth is the direction of the Sun measured clockwise from North. The figures are for mid-eclipse.
The Saros is a collection of eclipses belonging to a series. Each member of the series is followed by a similar eclipse approximately 18 years, 11 days and 8 hours later. This eclipse is a member of Saros number 127. It is the 56th eclipse out of a total of 82 in the series. The next eclipse of this series occured on 21 June 2001 and I saw it in Zimbabwe.
Gamma determines how the Moon's shadow, if extended, would pass through the Earth. A Gamma of zero implies that the shadow would pass through the exact centre of the Earth. A Gamma of greater than 1 misses the Earth and no total eclipse would occur. A positive Gamma passes North of the Earth's centre; a negative Gamma passes South of the Earth's centre. The value of Gamma for this eclipse is -0.4949. This means that the shadow passes South of the Earth's centre, about half of the way to the edge of the Earth. This, combined with the fact that in June, the Southern Hemisphere is tilted away the Sun, produces an eclipse in the Southern Tropical Zone.
The Diameter Ratio determines how much bigger the Moon's apparent radius is than the Sun's. In this case, the Moon's radius is 1.052 that of the Sun's. A total eclipse can only occur if this figure is greater than 1. The Moon would then appear larger than the Sun and could cover it completely. If this figure was less than one a total eclipse could not occur because the Moon would appear smaller than the Sun.
