Solar Eclipse Prime Page

Partial Solar Eclipse of -1686 Jul 31 (1687 Jul 31 BCE)

Fred Espenak

Introduction

eclipse map

The Partial Solar Eclipse of -1686 Jul 31 (1687 Jul 31 BCE) is visible from the geographic regions shown on the map to the right. 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 -1686 Jul 31 at 04:26:02 TD (17:34:31 UT1). This is 5.3 days after the Moon reaches apogee. During the eclipse, the Sun is in the constellation Leo. The synodic month in which the eclipse takes place has a Brown Lunation Number of -44630.

The eclipse belongs to Saros -1 and is number 74 of 74 eclipses in the series. Thus, the -1686 Jul 31 event is the last eclipse of the series . All eclipses in this series occur at the Moon’s ascending node. The Moon moves southward with respect to the node with each succeeding eclipse in the series and gamma decreases.

This is an extremely shallow partial eclipse. It has an eclipse magnitude of only 0.0063, while Gamma has a value of -1.5527. This is a very deep partial eclipse. It has an eclipse magnitude of 0.0063, while Gamma has a value of -1.5527.

The partial solar eclipse of -1686 Jul 31 is followed two weeks later by a total lunar eclipse on -1686 Aug 14.

Another solar eclipse occurs one synodic month after the -1686 Jul 31 eclipse. It is the partial solar eclipse of -1686 Aug 29.

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 39091.5 seconds for this eclipse. The uncertainty in ΔT is 2516.5 seconds corresponding to a standard error in longitude of the eclipse path of ± 10.51°.

The following links provide maps and data for the eclipse.

The tables below contain detailed predictions and additional information on the Partial Solar Eclipse of -1686 Jul 31 .

Eclipse Data: Partial Solar Eclipse of -1686 Jul 31

Eclipse Characteristics
Parameter Value
Eclipse Magnitude 0.00631
Eclipse Obscuration 0.00059
Gamma-1.55268
Conjunction Times
Event Calendar Date and Time Julian Date
Greatest Eclipse -1686 Jul 31 at 04:26:02.5 TD (17:34:31.0 UT1) 1105457.232303
Ecliptic Conjunction -1686 Jul 31 at 04:08:48.2 TD (17:17:16.7 UT1) 1105457.220332
Equatorial Conjunction -1686 Jul 31 at 04:37:26.3 TD (17:45:54.8 UT1) 1105457.240217
Geocentric Coordinates of Sun and Moon
-1686 Jul 31 at 04:26:02.5 TD (17:34:31.0 UT1)
Coordinate Sun Moon
Right Ascension07h33m08.6s07h32m44.9s
Declination+22°08'17.1"+20°42'06.2"
Semi-Diameter 15'54.4" 15'11.6"
Eq. Hor. Parallax 08.7" 0°55'45.6"
Geocentric Libration of Moon
Angle Value
l -3.5°
b 1.9°
c 10.9°
Prediction Paramaters
Paramater Value
Ephemerides JPL DE406
ΔT 39091.5 s
k (penumbra) 0.2725076
k (umbra) 0.2722810
Saros Series -1 (74/74)

Explanation of Solar Eclipse Data Tables

Penumbral Shadow Contacts and Extremes: Partial Solar Eclipse of -1686 Jul 31

Contacts of Penumbral Shadow with Earth
Contact Event Contact Time
TD		 Time
UT1		 Latitude Longitude
First External ContactP104:13:49.217:22:17.766°39.8'S099°48.4'W
Last External ContactP404:38:06.517:46:35.067°51.5'S085°54.9'W
Extreme Northern and Southern Path Limits of Penumbra
Contact Event Contact Time
TD		 Time
UT1		 Latitude Longitude
North Extreme Path Limit 1N104:17:35.917:26:04.466°22.1'S102°55.3'W
South Extreme Path Limit 1S104:34:19.017:42:47.667°50.0'S082°35.2'W

Explanation of Penumbral Shadow Contacts and Extremes Tables

Polynomial Besselian Elements: Partial Solar Eclipse of -1686 Jul 31

Polynomial Besselian Elements
-1686 Jul 31 at 04:00:00.0 TD (=t0)
n x y d l1 l2 μ
0 -0.32639 -1.53495 22.1446 0.55920 0.01298 240.2830
1 0.52309 -0.03347 -0.0064 -0.00009 -0.00009 14.9991
2 0.00002 -0.00008 -0.0000 -0.00001 -0.00001 0.0000
3 -0.00001 0.00000 - - - -
Tan ƒ1 0.0046505
Tan ƒ2 0.0046274

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 = 4.000

Explanation of Polynomial Besselian Elements

Links for the Partial Solar Eclipse of -1686 Jul 31 (1687 Jul 31 BCE)

Links to Additional Solar Eclipse Information

Calendar

The Gregorian calendar (also called the Western calendar) is internationally the most widely used civil calendar. It is named for Pope Gregory XIII, who introduced it in 1582. On this website, the Gregorian calendar is used for all calendar dates from 1582 Oct 15 onwards. Before that date, the Julian calendar is used. For more information on this topic, see Calendar Dates.

The Julian calendar does not include the year 0. Thus the year 1 BCE is followed by the year 1 CE (See: BCE/CE Dating Conventions). This is awkward for arithmetic calculations. Years in this catalog are numbered astronomically and include the year 0. Historians should note there is a difference of one year between astronomical dates and BCE dates. Thus, the astronomical year 0 corresponds to 1 BCE, and astronomical year -1 corresponds to 2 BCE, etc..

Eclipse Predictions

Predictions for the Partial Solar Eclipse of -1686 Jul 31 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 39091.5 seconds for this eclipse. The uncertainty in ΔT is 2516.5 seconds corresponding to a standard error in longitude of the eclipse path of ± 10.51°.

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.