Orwell Astronomical Society (Ipswich)

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Lunar Total Eclipse, 09 January 2001

Living in Ipswich, I suffer from bright skies and considerable light pollution. The last lunar eclipse that I saw was in September 1996: I attempted photography, but the longer exposures started to go yellow-green from the light pollution. For the lunar total eclipse of 09 January 2001, I decided to escape to the dark skies of Mike Harlow's garden, outside Ipswich, to attempt more photography.

During the drive to Mike's, the Moon was at low altitude and visible through thin cloud - not very encouraging! However, by midway through the partial phase the sky had cleared sufficiently to make photography worthwhile. Since the last eclipse I had acquired a Meade ETX 90 so I decided to try this. I set the Meade for a focal length of approximately 1450 mm but a rather small effective aperture of f/22. To compensate for the small aperture I used Ektachrome 1600 film. I also used a second camera, with a 500 mm f/8 lens and Elite Chrome 200 film. The second camera was three stops up on aperture and three stops down on sensitivity compared to the Meade, so that the exposure times for the two would be the same - this minimises the opportunity to make mistakes! The two cameras were mounted on a Vixen drive. A sample of my results is below.

Fig. 1. 19:19 UT. Partial phase. 1/30 s exposure, ETX. This looks OK but a slower film (say ISO 100) would still have required an exposure of only 1/2 s and the result would have been less grainy.
Fig. 2. 20:00 UT. Totality. 30 s exposure, ETX. Because the mount nominally drives to follow the stars there is a certain degree of blurring of the Moon. If I had doubled the exposure the Moon would have been brighter but the blurring would have been unacceptable. Note the naked eye (magnitude 5.2) star star 63 Gem to the east of the Moon.
Fig. 3. 20:40 UT. Totality. 8 s exposure, ETX. Although this is dark it is sharper as the Moon drifted less relative to the stars during the exposure.
Fig. 4. 20:00 UT. Totality. 30 s exposure, 500 mm lens. Blurring is not visible on this scale. A slight orange glow is visible around the Moon, presumably from faint clouds or haze.

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

After totality ended I noticed that I had condensation on the front element of the ETX - must build a dew cap, with or without a heater! During the outgoing partial phase the clouds started to roll in from the south-west and, by 21:15 UT, had obscured the Moon for good,preventing further photography.

So what would I do differently with next time? I would use the ETX on the shorter 1250 mm f/16 setting and keep the exposures the same, giving a brighter image.

More Information on Eclipses

See Fred Espenak's eclipse web site eclipse.gsfc.nasa.gov/eclipse.html.

Nigel Evans