The Moon's Brightness during the January 21, 2019 Total Lunar Eclipse


The writer measured the brightness of the Moon during the January 21, 2019 total lunar eclipse. He used a single channel SSP-3 photometer along with filters transformed to the Johnson B and V system. He also used a small telescope having a diameter of 0.030 m with a focal length of 0.12 m. This combination produced a field of view of 56 arc-minutes which is large enough to cover the entire Moon. Data were collected between 4:43 and 5:31 U.T. on January 21, 2019. The V-filter brightness dropped from -3.18 at 4:43 UT to -2.04 at 5:13:30 UT. Afterwards, it rose back to -2.70 magnitude by 5:31 UT. The B-filter brightness (in magnitudes) went from -1.76 at 4:45 UT to -0.32 at 5:14:30 to -0.98 at 5:30:30 UT. The corresponding B-V value was 1.72 at minimum brightness. This is much higher than the corresponding value of the uneclipsed Moon. It is concluded that fully eclipsed Moon reached a similar brightness as similar events since 2000.

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