Penumbral Lunar Eclipse of 2581 Apr 20
Fred Espenak
Introduction
The
Penumbral Lunar Eclipse of 2581 Apr 20
is visible from the geographic regions shown on the map to the right.
The diagram above the map depicts the Moon's path with respect to Earth's umbral and penumbral shadows.
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 2581 Apr 20 at 07:01:03 TD (06:35:20 UT1).
This is 4.9 days after the Moon reaches apogee.
During the eclipse, the Moon is in the constellation Virgo.
The synodic month in which the eclipse takes place has a Brown Lunation Number of 8142.
The eclipse belongs to Saros 131 and is number 65 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 deep penumbral eclipse.
It has a penumbral eclipse magnitude of 0.9754 and a penumbral eclipse duration of 272.3 minutes.
Gamma has a value of 1.0415.
The penumbral lunar eclipse of 2581 Apr 20 is followed two weeks later by a total solar eclipse on 2581 May 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
1542.8
seconds for this eclipse.
The uncertainty in ΔT is
379.0 seconds corresponding to a standard error in longitude of the eclipse visibility zones of 1.58°.
The following links provide maps and data for the eclipse.
The tables below contain detailed predictions and additional information on the
Penumbral Lunar Eclipse of 2581 Apr 20
.
Polynomial Besselian Elements: Penumbral Lunar Eclipse of 2581 Apr 20
| Polynomial Besselian Elements |
| 2581 Apr 20 at 07:00:00.0 TD (=t0) |
| n |
x |
y |
d |
f1 |
f2 |
f3 |
| 0 | 0.41404 | 0.86900 | 0.2047 | 1.20202 | 0.66992 | 0.25185 |
| 1 | 0.43167 | -0.21032 | 0.0002 | 0.00032 | 0.00032 | 0.00009 |
| 2 | 0.00017 | -0.00005 | -0.0000 | 0.00000 | 0.00000 | 0.00000 |
| 3 | -0.00000 | 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 = 7.000
Explanation of Besselian Elements
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
Penumbral Lunar Eclipse of 2581 Apr 20
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
1542.8
seconds for this eclipse.
The uncertainty in ΔT is
379.0 seconds corresponding to a standard error in longitude of the eclipse visibility zones of 1.58°.
Acknowledgments
Some of the content on this web site is based on the book Thousand Year Canon of Lunar 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.
