During a lunar eclipse where the Earth passes between the Sun and the Moon, the shadow of the Earth slowly covers the Moon and its features are eclipsed. If we observe and time these events, data can be computed to determine the enlargement of the shadow known as the UMBRA. The enlargement of the umbra is due to refraction of the atmosphere and its true shape which is not circular, can also be found.
Observations
Observe the Moon well before the night of the lunar eclipse to become familiar with the best lunar features. I have produced a list of 60 craters under the internal link Immersions, which you could use. As the eclipse of 2003 November 9 is a total eclipse, all of these craters will eventually be immersed into the umbra and will re-appear as the eclipse gradually comes to a close. These immersion and emersion predictions are for mid-crater events, where the umbra intersects the crater. However, observations of umbral contact with the edges of each crater as explained below, can also be analysed to give greater accuracy for the size and shape of the umbra.
Use a mounted telescope, or steadied binoculars to achieve a full image of the Moon so that orientation of the Moon and its features will be easier to remember - a magnification of around 20 to 50 is sufficient.
On the night of the eclipse you will need an assistant or a tape recorder, to make a history of your observations with an accurate timing source such as a short wave timing signal to give an accurate timing base to go with your reports of umbral contact with each of your favourite craters. On my web page for this eclipse, under the internal link Immersions are a list of mid-crater timing predictions for the first half of the eclipse, and under the internal link Emersions are a list of mid-crater timing predictions for the last half of the eclipse.
Contacts
Try to record all four contacts with each crater, two in the early part of totality (first and second contact) as illustrated below for the crater Copernicus:
Difficulties
Some difficulties may be experienced with the clarity of the edge of the umbra as it is not as well defined as shown in the above images. The umbral edge slowly changes from light to darkness over a range in its radius, so you will need to decide on a set distance from the edge and keep this in mind for all craters timed. Try and be as consistent as possible.
There may also be some difficulty in finding a clear short wave timing signal on the night of the eclipse, but some known radio frequencies are given here. You may be able to have someone call out the time every five minutes as your tape recorder accuracy will allow interpolation after the eclipse to the nearest second in time for each crater timing event using a stop watch.
Primary Contacts
One other observation of value is the times of primary contact when the umbra first touches the edge of the Moon (first primary contact), when the Moon is fully immersed in the umbra (second primary contact), the time the umbra begins to leave the Moon (third primary contact) and at the end of the eclipse where the umbra completely leaves the Moon (fourth primary contact).
Oblateness
On my web page for this eclipse under the link Circumstances, the expected times for primary contact are given for the normal eclipse contacts and at the bottom of the page, are the expected departures from these times due to the oblateness of the umbra. Your timings of each primary contact will help check the observed value of oblateness.
Evaluation
Please submit your crater and primary contact times by email providing the four contacts for each named crater, or mid-crater timings (the time at which the observed umbra passes over the center of the feature) for analysis to:
Once these timings are received a computer analysis will be made of all types of timings made by each observer, to determine the % enlargement of the umbra and the resulting observed umbral oblateness from acceptable data (the acceptability is base on the limits of %E betwen 0 and 4%).
Each observer will be notified if a return email address is given, and comparitive results will be posted on my web page.