Total Lunar Eclipse of December 21, 2010

 

Observation Report and Comments

 

Helio de Carvalho Vital

 

 

Location: Rio de Janeiro (22o55`24 S; 43o13` 42 W; Alt.=30m), Brazil

 

Instruments: 2.4 f/13 refractor at 40x (used for timings) and Canon SX20 IS digital camera at 25x and ISO 800 (used for pictures, not attached to telescope).

 

Atmospheric conditions: Good transparency and excellent stability; clear skies; morning twilight in progress after 07:00 UT.

 

Local altitude of the Moon: from 17o (U1) to 5o (last photo) with moonset predicted for 8:07 UT.

 

First naked-eye perception of the penumbral shading of the northeastern limb of the Moon`s disc occurred at 6:03 UT when the magnitude of the penumbral eclipse was 0.58.

 

Limb and Mid-Crater Contact Timings

 

Immersions

UT

Partial Phase (U1)

06:33:08

Grimaldi

06:38:05

Campanus

06:47:04

Kepler

06:52:06

Aristarchus

06:56:38

Copernicus

07:00:14

Pytheas

07:04:58

Timocharis

07:10:37

Dionysius

07:15:56

Manilius

07:16:33

Menelaus

07:19:20

Goclenius

07:23:08

Langrenus

07:27:11

Eudoxus

07:28:32

Proclus

07:31:20

 

Estimate of the Eclipse Brightness

 

Poor contrast due the combination of the very low altitude of the Moon and the influence of the morning twilight prevented magnitude estimates to be made. However, based on the visibility of the limb and of features in the umbra, the Danjon Number was estimated as L=2.4 (0.4). According to the correlation we have determined between L and the Moon`s magnitude (m), that would correspond to an approximate mid-totality value of m≈ -1.6. Such figures, if confirmed, would indicate a moderately bright eclipse, as bright as it could be considering the position of the Moon inside the umbra, thus not significantly obscured by volcanic aerosols in the stratosphere as expected.

 

Photos

 

The advance of the umbral shadow during immersion was captured by the author in picture 1. Overexposures revealed more and more orange-colored regions inside the progressing umbra during the first partial phase of the eclipse as totality approached and the Moon was about to hide behind a faraway hill just a few minutes before moonset (picture 2).

 

 

 

Lunissolar (Eclipses)/REA/Brasil