 SPA News Circular 258 |
Apart from the quarterly magazine Popular Astronomy, the SPA publishes regular newsletters to keep members up to date with latest discoveries in astronomy and professional research. If a new bright comet or a nova is spotted, you will read about it in the News Circulars. We also keep up to date with news from professional observatories and the latest results from Hubble and planetary probes. The News Circulars' other major role is to report on members' own work for the SPA observing sections. Section directors write regular columns which could include YOUR own observations. |
ISSUE 258
The Holmes and Tuttle Show
Major flare-up of 17P/Holmes. Comet 17P/Holmes was discovered by Edwin Holmes from London on 1892 November 6. He had been observing in poor conditions, and decided to have a look at the Andromeda Galaxy (M31) with his 32cm reflector before stopping for the night. He found an unexpected object that wasn't M31. Other observers were initially skeptical, but the comet was soon confirmed. It remained bright for several weeks before slowly fading, and then underwent another outburst in mid-January 1893, which again brought it within naked eye range. At its eight following returns the comet was a faint object
17P was reported in outburst by Spanish amateurs on 2007 October 24, when near opposition, but well past perihelion, which was back in May. The brightest estimates so far suggest that it reached 2.5 on October 25, a rise of about 14 magnitudes, but what it will do now is uncertain. If it retains its present intrinsic brightness it could still be a naked eye object at the end of the year.
Best ever return of comet Tuttle. 8P/Tuttle is likely to be one of the brighter objects for observers over the coming months. It could be a binocular or even naked eye object at the beginning of the New Year, as it makes a close pass of the Earth at 0.25 AU before reaching perihelion at 1.03 AU in late January 2008. This is the closest pass to the Earth that it has made since before discovery, although there will be a closer one in 2048.
Occultations - Regulus Grazed By Moon
Since the last report, there have been two outstanding events. The first and perhaps most beautiful, because of the proximity of brilliant Venus and bright Saturn, was the grazing occultation of Regulus (Alpha Leonis). This event, which took place around 05h 30m UT on October 7th, was particularly beautiful not only because of the nearness of the two planets, but also because the night hemisphere of the Moon was glowing dimly with Earthshine.
The event was widely observed by many members, and some good results and timings were made along the graze-line, which stretched from Lytham St Annes (Lancashire) in the west, to Grimsby (Lincolnshire) in the east.
Meteor Update
Perseids. Some fine weather coincided with the Perseid maximum weekend for many parts of the British Isles this year, and observers were out in droves. By midnight UT on August 11-12, average Zenithal Hourly Rates (ZHRs) had reached 50-60 in SPA data, but seemed little better by the following night, closest to the expected, possibly multiple, maximum, averaging a fairly constant 60-70 between 23:30-03:00 UT. In the hour or so around 22:00 UT on August 12-13, ZHRs reached their highest in our results, at about 80 +/- 15, even though the radiant was still fairly low then. This was somewhat below their normal best, but still a fine display for all that.
Mars Tops the Target List
Since the last News Circular report, the Planetary Section has seen a large increase in the number of observations it has received from both visual observers, sending in their sketches, notes and intensity estimates, and from several first rate imagers. Mars has been the most observed target for both groups.
The Section has enjoyed tremendous support from David Tyler, who has supplied many stunning images of Jupiter, Mars and Saturn. David's recent images of Mars reveal a wealth of intricate detail. Other first class images of Jupiter, Mars and Saturn have been supplied by Pete Lawrence, who, like David, is a truly gifted imager with the patience of Job. Mike Brown has also provided the Section with many excellent images of Venus and Mars, imaged through his excellent 250mm planetary Newtonian.
