Photometric observation of the total Lunar eclipse on 9th November 2003

A simple photometer was constructed for photometric observation which was able to measure luminous intensity of the Moon during the eclipse.

At the opening of photometer was the lens with 100 mm in diameter and focal length of 165 mm, and for the sensitive element a photoresistor of unknown characteristics and 6 mm in diameter was used. Since the diameter of the Moon image in focus is D = F / 110, e.g. 1.5 mm, the field of view of this photometer is some 2°. This is very important because the field of view included Moon's immediate proximity beside its disc, and its diffuse emission is also being measured. Readings were carried out with a classic multimeter every 30 seconds to determine the change of resistance as a function of luminous intensity. Since photoresistor's "resistance of background" is beyond the scope of measuring instrument (2MΩ), it was necessary to bind parallel 2MΩ resistor to enable that value be maximal as well. The resistance of dark frame varied at 1986kΩ, and the lowest measured intensity was 1981kΩ. Multimeter itself was powered by a 9V battery, bind to an improvised push button which was used to turn it on before every measurement.

In order to provide the tracking of celestial sphere photometer was mounted to a telescope. Measurement started just before the umbra contact, at 0h 20m 00s UT, nevertheless after the short period of time an appreciable difference between the luminous intensity of the full and partially eclipsed Moon was detected.
Click here for bigger picture...Results are shown in the graphic. What distracts at the most is an elevated part of the curve at the beginning, which is a consequence of an instrument error. Since between the III and IV contact a quick rise of fog occurred, measurement was aborted, which is also obvious from the graph. However, despite the poor weather conditions days before and after the eclipse, clear skies during the eclipse were enough to produce some results.