Partial Lunar Eclipse of 1991 Dec 21

Fred Espenak

Key to Lunar Eclipse Figure (below)

Introduction

The Partial Lunar Eclipse of 1991 Dec 21 is visible from the following geographic regions:

  • Asia, Australia, Pacific, Americas

The diagram to the right depicts the Moon's path with respect to Earth's umbral and penumbral shadows. Below it is a map showing the geographic regions of eclipse visibility. Click on the figure to enlarge it. For an explanation of the features appearing in the figure, see Key to Lunar Eclipse Figures.

The instant of greatest eclipse takes place on 1991 Dec 21 at 10:33:60 TD (10:33:01 UT1). This is 1.0 days before the Moon reaches perigee. During the eclipse, the Moon is in the constellation Taurus. The synodic month in which the eclipse takes place has a Brown Lunation Number of 853.

The eclipse belongs to Saros 115 and is number 56 of 72 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.

This is a very shallow partial eclipse. It has an umbral eclipse magnitude of only 0.0876 and a partial eclipse duration of 64.1 minutes. Gamma has a value of 0.9709.

The partial lunar eclipse of 1991 Dec 21 is followed two weeks later by a annular solar eclipse on 1992 Jan 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., TD = UT1 + ΔT). ΔT has a value of 58.3 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 Partial Lunar Eclipse of 1991 Dec 21 .

Eclipse Data: Partial Lunar Eclipse of 1991 Dec 21

Eclipse Characteristics
Parameter Value
Penumbral Magnitude 1.06511
Umbral Magnitude 0.08762
Gamma 0.97094
Epsilon 0.9877°
Opposition Times
Event Calendar Date & Time Julian Date
Greatest Eclipse 1991 Dec 21 at 10:33:59.7 TD (10:33:01.4 UT1) 2448611.939600
Ecliptic Opposition 1991 Dec 21 at 10:24:08.9 TD (10:23:10.6 UT1) 2448611.932761
Equatorial Opposition 1991 Dec 21 at 10:24:53.1 TD (10:23:54.8 UT1) 2448611.933273
Geocentric Coordinates of Sun and Moon
1991 Dec 21 at 10:33:59.7 TD (10:33:01.4 UT1)
Coordinate Sun Moon
Right Ascension17h55m52.1s05h56m15.5s
Declination-23°26'13.9"+24°25'15.3"
Semi-Diameter 16'15.5" 16'38.0"
Eq. Hor. Parallax 08.9" 1°01'02.6"
Geocentric Libration of Moon
Angle Value
l -2.0°
b -1.3°
c -1.9°
Earth's Shadows
Parameter Value
Penumbral Radius 1.3010°
Umbral Radius 0.7591°
Prediction Paramaters
Paramater Value
Ephemerides JPL DE405
ΔT 58.3 s
Shadow Rule Danjon
Shadow Enlargement 1.010
Saros Series 115 (56/72)

Explanation of Lunar Eclipse Data Tables

Eclipse Contacts: Partial Lunar Eclipse of 1991 Dec 21

Lunar Eclipse Contacts
Eclipse Event Contact Time
TD		 Time
UT1		 Zenith Latitude Zenith Longitude Position Angle Axis Distance
Penumbral BeginsP108:28:13.408:27:15.124°31.5'N128°36.3'W 313.9° 1.5776°
Partial BeginsU110:02:00.010:01:01.724°26.9'N151°02.1'W 347.6° 1.0361°
Greatest EclipseGreatest10:33:59.710:33:01.424°25.3'N158°41.3'W 5.2° 0.9877°
Partial EndsU411:06:04.811:05:06.524°23.5'N166°21.8'W 22.8° 1.0364°
Penumbral EndsP412:39:47.912:38:49.624°18.2'N171°13.1'E 56.5° 1.5788°
Eclipse Durations
Eclipse Phase Duration
Penumbral (P4 - P1)04h11m34.5s
Partial (U4 - U1)01h04m04.8s

Explanation of Lunar Eclipse Contacts Table

Polynomial Besselian Elements: Partial Lunar Eclipse of 1991 Dec 21

Polynomial Besselian Elements
1991 Dec 21 at 11:00:00.0 TD (=t0)
n x y d f1 f2 f3
0 0.34253 0.96075 -0.4091 1.30112 0.75917 0.27724
1 0.58532 -0.05309 -0.0000 0.00021 0.00021 0.00006
2 0.00009 -0.00026 0.0000 -0.00000 -0.00000 -0.00000
3 -0.00001 0.00000 - - - -

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 Besselian Elements

Eclipse Publications

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For more visit: AstroPixels Publishing


Links for the Partial Lunar Eclipse of 1991 Dec 21

Links to Additional Lunar Eclipse Information

• Decade Tables of Lunar Eclipses:
| 1901 - 1910 | 1911 - 1919 | 1921 - 1930 | 1931 - 1940 | 1941 - 1950 |
| 1951 - 1960 | 1961 - 1970 | 1971 - 1980 | 1981 - 1990 | 1991 - 2000 |
| 2001 - 2010 | 2011 - 2020 | 2021 - 2030 | 2031 - 2040 | 2041 - 2050 |
| 2051 - 2060 | 2061 - 2070 | 2071 - 2080 | 2081 - 2090 | 2091 - 2100 |

Lunar Eclipse Publications

Eclipse Predictions

Predictions for the Partial Lunar Eclipse of 1991 Dec 21 were generated using the JPL DE405 solar and lunar ephemerides. The lunar coordinates were calculated with respect to the Moon's Center of Mass.

The Earth's umbral and penumbral shadows were calculated using the Danjon methodusing a mean mid-latitude ellipticity to compensate for the opacity of the terrestrial atmosphere.

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 58.3 seconds for this eclipse.

Acknowledgments

Some of the content on this web site is based on the book 21st Century Canon of Lunar Eclipses. 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.