Map the Moon During Tomorrow’s Lunar Eclipse

Please help us accurately map the edge of the Moon by timing occultations
of stars during the August 28th total lunar eclipse (Tuesday morning
in Hawaii and the western parts of the Americas, and Tuesday evening in
Australia and New Zealand). This information is needed to help analyze
total and annular solar-eclipse observations to determine solar-radius
variations, since the Baily's Beads phenomena recorded during some
past solar eclipses are caused by the same lunar features that will
cover and uncover stars during the lunar eclipse. Especially needed are video or
CCD timings of the occultations, especially of reappearances, and of
grazing occultations that occur during the eclipse.

You can calculate predictions for lunar occultations for your observing
site using Occult, which is available for downloading for free on
the International Occultation Timing Association's lunar-occultations website. Timing methods are also described there.

Maps showing grazing occultations of stars of mag. 9.5 and
brighter, with corresponding tables, are in the August 28th eclipse
grazes section of IOTA's Asteroidal Occultation website. Especially
good are grazes of 7.8-mag. stars, with path #2 (ZC 3282) being a
northern limit passing near Redding, CA; n.w. of Boise, ID; near
Great Falls, MT; and a short distance n.w. of Moose Jaw, Sask.
Derek Breit has an interactive Google map for this graze, allowing
you to see the path in great detail.

Another good one is path #7,
a southern-limit graze of SAO 165048 passing over n.w. Oregon,
s.e. Washington, southern Alberta, and near Saskatoon, Sask.
Besides ZC 3282, Derek has Google maps for a graze of 11.1-mag. X182578,
whose path passes near Rohnert Park, Beale AFB, and
Nevada City, Calif.; and for path #8 (8.6-mag. SAO 165040) a
little north of #2. Google maps can be prepared for grazes
other than the ones mentioned above on request to either Brad
Timerson at or Derek Breit at
For example, the paths for two
9.4-9.5-mag. stars pass near San Luis Obispo, Bakersfield,
and Ridgecrest, Calif., and Las Vegas, Provo, and Greeley, CO,
and others pass near Hermosillo, Las Cruces, El Paso, and

For more information and instructions for reporting your observations, see IOTA's
lunar-occultations website:

David W. Dunham

Contributing Editor

Sky & Telescope

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