Wednesday, March 3, 2010

The return of periodic comet 10P/Tempel

According to the ephemerids, comet 10P/Tempel is expected to reach (about) magnitude +8 next July. Currently 10P is visible (with some difficulties) in the early morning sky, pretty low in the south-east horizon, within the constellation of Serpens.According to the Minor Planet Center ephemerids, it's currently supposed to have an m1 of about 13.5; however in our images (details in the caption) this object is a modest target:

We measured it at (unfiltered Red) magnitude nearly 18, with a tiny coma of about 15 arcsec in diameter. Image enhancement techniques didn't provide any appreciable extent to the measured coma. One possibility is that, like other short period comets, 10P will develope an appreciable coma when it will get closer to the Sun (currently it's beyond the orbit of Mars, at about 2 AU from our star). Obviously we cannot rule out the hypothesis that the moonlight disturbance and/or the low altitude of the object on the horizon might have compromised the detection of a faint external coma (in spite of the fact that the sky was pretty clear and transparent).

The Afrho parameter (proxy of the dust abondance within the coma) currently is about 15 to 20 cm, like other short period comets at this distance, prior to their perihelion. Finger crossed for a neat binocular comet next summer.

Giovanni Sostero & Ernesto Guido

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