May 4th 2004 Total Lunar Eclipse

 

Observation Report by Helio C. Vital

 

Location: Tijuca, Rio de Janeiro, RJ, Brazil (Lat-Long-Height: -22 55' 21" , -43 13' 42", 30m)

Time Span: from 20:55 till 21:43 UT

Local Rise Time of the Moon: 20:21 UT

Atmospheric Conditions: good stability but very poor seeing due to dry fog and high cirrus clouds just above the horizon. Thick Clouds prevented observation after 21:43 UT.

First Visibility of Moon: 20:55 UT (naked eye) - totally eclipsed Moon first noticed only 6 degrees above horizon

 

Totality

Prevailing colors of the lunar disk: mostly copper-like; greenish-yellowish band next to the umbral border at U3

Apparent brightness of the totally eclipsed Moon: approximately equal to that of Jupiter at 21:04. Accounting for the light extinction differential (-1.60.4), that means that the Moon was shining at -2.2 + -1.6 = -3.8 (0.4). However, from our light curve of the 2003 May 16th eclipse, we gather that 4 minutes before U3 a +1.2 (0.3) correction is required to yield the magnitude of the Moon at mid-totality, that yields m= -2.6 (0.5). Our correlation based on many previous eclipses predicted -1.7 (0.5)(1σ). That figure, if confirmed, would mean that the Moon remained significantly brighter than expected during totality, maybe an indication that a below-average stratospheric concentration of volcanic aerosols was probed over mid-southern latitudes.

Visibility of the lunar disk: some major features and the entire limb were noticed through the C8.

 

 

Partiality

Features of the umbral border: well-defined (probable indication of no major ozone depletion at mid-southern latitudes)

Crater Timings during Emersions: Five mid-crater timings have been made as shown in the table below. Apparently, in good agreement with predictions based on a 2% atmospheric umbral enlargement. Very poor contrast prevented timings to be made before 21:22 UT and so did a thick blanket of stratus clouds after 21:43 UT.

 

Crater

Emersion (UT)

Atmospheric Umbral Enlargement (%)

Tycho

21:24:06

1.75

Kepler

21:29:00

2.08

Aristarchus

21:30:01

2.01

Copernicus

21:36:54

2.00

Pytheas

21:39:02

1.61

Mean Enlargement = 1.890.09%

Oblateness = 1/117 (0<O<1/57) (2σ)

Authors_Photos

Index

 

[email protected] Helio C. Vital

 

 

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