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Journal

No 55 - March 2008

Recent observations

Comets

As reported at the last minute in ASE Journal 54, comet 17P/Holmes surprised astronomers with an outburst in late October that boosted its brightness 500,000-fold above expectations. It was brighter than 3 mag compared to the predicted 17 mag. Horst Meyerdierks followed it from late October until the end of December, measuring coma diameter and brightness in dSLR images.

Horst also imaged 8P/Tuttle on three occasions in late December and early January. This comet behaved more to the predictions, being just brighter than 7 mag. It was moving rather quicker than Holmes from Cassiopeia past M33 and into Pisces.

Sun

Horst takes an image of the Sun whenever possible and averages his spot counts in 30-day intervals. He reports the following R numbers (number of spots plus ten times the number of spot groups):

2006-12-11 / -01-09 14.9 -07-09 / -08/07 8.9
2007-01-10 / -02-08 20.8 -08-08 / -09/06 6.9
-02-09 / -03-10 5.8 -09-07 / -10/06 2.3
-03-11 / -04-09 2.2 -10-07 / -11-05 1.1
-04-10 / -05-09 4.2 -11-06 / -12-05 4.4
-05-10 / -06-08 15.7 2007-12-06 / -01-04 5.0
-06-09 / -07/08 9.9 2008-01-05 / -02-03 3.1

Early in 2007 it appeared that the minimum of sunspot activity might have occurred in March, but after a more active summer October turned out even lower spot counts.

Variables

Horst observed the minimum on 2007-10-23 of the eclipsing binary RZ Cas. He measured the brightness in dSLR images taken at 15 min intervals. Each image was a tracked single frame of 20 s exposure taken with a 400 mm f/6.3 (63 mm aperture) lens. RZ Cas has an amplitude of 1.4 or 1.5 mag and the data have an accuracy of 0.04 mag.

Des Loughney in January observed the eclipsing binary VW Cep with an amplitude of only 0.4 mag. His data are also accurate to 0.04 mag. But Des used a stationary dSLR with 200 mm f/3.5 (57 mm aperture) lens and averaged 10 frames of 2.5 s exposure.

Lunar halo

The lunar halo of Christmas Eve was seen by various observers in the Central Belt, certainly from Edinburgh to Falkirk and Stirling. Frank Howie made the picture shown here.

lunar halo
A light mist made this lunar halo even more beautiful on a cold, Christmas Eve, 2007. Mist reduced the contrast of the overall scene, clearly revealing discernible colour tinges in the halo - like a faint, 360° softly coloured rainbow. An extra bonus was the presence of Mars within the halo at the 2 o'clock position. All this beauty, despite the bright sodium street lights in the immediate vicinity of the observing site (Morningside, Edinburgh). Photograph and caption by Frank Howie.

Contents

Cover page

Society news

Astronomical Society of Edinburgh - Annual General Meeting

"Conjunction"

Astronomical Society of Edinburgh - Annual Report for 2007

UN declares Year of Astronomy

Scottish Astronomers Group - reincarnated

UK astronomy in funding crisis

John Christopher Bartholomew, MA. FRSGS. FRSE.

Book review: The lost language of the stars

Recent observations

Forthcoming events

Asteroid "Harryford" 6907

About the ASE Journal


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