Orwell Astronomical Society (Ipswich)
Fireballs, 30 July 1973 - 12 January 1986
On Saturday 27 May 1972, a meteor disintegrated in the atmosphere over Suffolk producing red, green and bluish trains. The coastguard mistook the lights in the sky for distress flares and launched the Lowestoft lifeboat! Reports of the incident appeared in the local press and were reported in the May 1972 OASI Newsletter. The incident stimulated the interest of members of OASI in observing fireballs. Initially Charles Radley collated observing reports of the phenomenon and, from the late 1970s onwards, David Barnard undertook this role. Members of OASI reported observations of fireballs from 1973 to 1986; the reports are summarised below.
In 1976, OASI purchased a camera which was used from 1978 to 1986, primarily by Alan Smith, as an all-sky fireball camera. The camera captured many images of fireballs, some of which are reproduced below.
Note: an appeal for more observations of the fireball was published in the Ipswich Evening Star newspaper on 10 August. OASI received a report from a Mr S J Anderson in Luton. By combining his report with that from OASI member Percy Fulcher it was possible to estimate the track of the fireball as follows: it started near Dieppe on the French Coast at an altitude of about 150 km, travelled north crossing the English Coast near Eastbourne, passed over Herstmonceux and disintegrated over the Essex/Cambridge border near Saffron Walden at an altitude of 60 km. The colour and track of the fireball suggested that it was associated with the Alpha Capricornid or Delta Aquarid meteor showers.
Track: in the north at a low elevation, travelling to the horizon at an angle 30° from the east, lasting over three seconds, perhaps as long as eight seconds.
Colour: slight green colour with a reddish tail.
Track: from Andromeda to Aries, passing 1° from the Square of Pegasus. Disintegrated at the end of the track. Track length approx 25°.
Train: 10° length at maximum extent.
Note: independent observers, one in Dartford and one in West Drayton, also provided observations of this fireball. Analysis of the three observations indicated that the object travelled across the Thames estuary or southern North Sea, starting at 2° 0' E, 51° 50' N, 150 km (±20 km) altitude and ending some 25 km away at 1° 20' E, 51° 40' N, 40 km (±15 km) altitude, some 20 km off the Essex coast between Clacton-on-Sea and Frinton-on-Sea.
Track: from approx 50° altitude in the north-west to approx 20° altitude in the west-north-west.
Colour: intense white colour.
Note: this fireball appeared approximately three minutes after the reappearance of Saturn from a lunar occultation.
Track: started in Cygnus, moving very fast in the direction of Jupiter (in Aquarius). Just after passing Delphinus, the object broke into a wide trail with fragments shooting off the sides. Approximately 15° N of Jupiter the fireball died with no visible after-trail or sonic boom.
Colour: intense white.
Note: the fireball is believed to be a member of the Delta Cygnids, which comes to maximum on 20 August.
Track: started between Cepheus and Cassiopeia, moved south-west through Cepheus and finished in the area bounded by Draco, Lyra, Cygnus and Cepheus. The object's motion lasted for approximately three seconds before the nucleus disintegrated, leaving trails visible for approximately one second.
Colour: nucleus was intense white. The fireball left four yellowish trails of magnitude -1.
Track: started on the boundary of Ursa Major and Leo Minor at RA 10h 50m, dec +40° and ended on the border of Ursa Major and Draco at RA 13h 30m, dec +63°.
Train: persisted for several seconds.
Note: this fireball might have come from the Leonid shower. Although premature, its track seemed to originate from the radiant in Leo.
On Sunday 06 June 1976, at approximately 21:30 UT, a magnitude -10 fireball was seen across southern England. The Meteor Section of the BAA is undertaking a thorough investigation, and anyone who observed the object is urged to contact the Section Director. It appears that the fireball commenced around Gloucestershire and ended in the East Anglian region and was accompanied by a loud bang, probably due to the outer layers fragmenting. A couple of members of OASI saw the object. The Ipswich Evening Star devoted a column to the object on the 07 Junue issue. Meteorites could be lying in our area thanks to this object!
At once I rang Bob Malster and asked him to put an appeal for reports of the fireball in the next East Anglian Daily Times newspaper, which he duly did. The appeal resulted in news of six sightings by approximately ten people. I sent a report to Keith Hindley, BAA Meteor Section Director. Recently Keith sent me an interesting letter (parts reprinted below). I would like to take this opportunity to thank everyone who sent me details of their observations. Please send future fireball sightings to David Barnard, Director of the OASI Meteor and Fireball Section.
This is just a short note about the 1976 August 22 fireball. Many thanks again for doing so much work which was much appreciated. We received one or two other sightings, but the fireball was certainly not widely observed.
I am delighted to report, however, that we wrote at once to Dr Zdenek Cepleche, leader of the European Network, and he has just written to report that the fireball was photographed by two members of the European Network, station 55 (Marienberg) and station 59 (Nurnburg). These are the two most north-westerly stations of the European Network.
The fireball began at about 80 km altitude some 70 km NW of Dusseldorf and ended at about 50 km altitude about 25 km WSW of Dusseldorf. The start height is a photographic one (i.e. when the fireball brightened to approximately magnitude -7). Visually (i.e. when the fireball brightened to magnitude above +6 or +4) the start height would have been over 100 km. The meteor was of peak absolute magnitude -10 to -11 and did not result in a meteorite fall. It was probably carbonaceous in nature and completely disintegrated during its flight.
It is interesting to note that the fully corrected end bearings from Ipswich of all our reports (allowing for conversion from magnetic to true bearings) is 101.6° ±0.9°. The true bearing of the photographic end-point above is actually 103° - a pretty good agreement under the circumstances and showing that the survey method is a good one.
Dr Cepleche wishes me to thank you for the field work, which he found particularly useful. Many thanks from me too for the good work - I hope that you have another fireball event to get your teeth into soon.
Signed Keith Hindley
Track: moving southwards at steady speed. The observers reported two loud bangs and a hissing noise.
Colour: red and yellow.
Train: about one minute duration.
Note: the Ipswich Evening Star newspaper and Radio Orwell featured the fireball and the publicity generated ten reports of sightings that evening. Most were from passengers on aeroplanes between 19:00 and 22:00 UT, and none seemed to confirm the fireball at 17:00 UT. In a triumph of optimism over experience, Jeremy and Michael together with David Barnard, Roy Cheesman and his two sons hunted for possible meteorites along the foreshore of the River Orwell, but without success!
Track: a Perseid passing from Cepheus into Draco.
Colour: red and yellow.
Train: visible for approximately 45 seconds after the fireball disappeared.
Track: east to west. The fireball underwent several flares during its passage across the sky.
Track: started 2° W of Mars and finished 1° E of Pollux.
Magnitude: -5 to -10.
Compass bearing: SSW.
Track: started in Delphinus, fading out about 20° from the horizon, breaking up into about five pieces.
Train: none, sparkler-like.
Moon: 10 days old.
Compass bearing: NE.
Track: broke into six pieces.
Disappearance: 30° altitude.
Path: started at RA 8h, dec 37°N, ended at RA 9.5h, dec 8°N (approx). Passage lasted 15-20 seconds.
Colour: white, flaring before fragmentation into two unequal components just before disappearance. Left no trail.
Disappearance: 30° altitude.
An interesting fireball was seen in the Essex-Suffolk region of England at 21:57 UT on 03 June 1980. I have received only a few observations, all of which were due to the efforts of Alan Smith of the Orwell Astronomical Society (Ipswich).
It has not been possible to deduce an accurate track for the object, but sufficient evidence has been provided to indicate that it travelled on a bearing of approximately 80°, crossing the East Coast between Felixstowe and Walton-on-the-Naze. The object first became visible some distance west of Colchester as a dull orange-red disk which brightened rapidly to a brilliant red and then suddenly changed colour to a brilliant green. The object suddenly faded when well out over the North Sea. Observers reported that fragmentation (red sparks) occurred from when first seen until the object faded. A short trail was recorded, but no-one observed a persistent trail after the fireball faded.
The object, although said to be brighter than the Full Moon, was reported consistently as relatively small, the description suggesting a size of about five arcmin. The object travelled across the sky at quite high speed, its duration being about three seconds. There were no reports of sound effects.
Path: NW to SW with a passage lasting approximately four seconds.
Track: from east to west.
Duration: circa 9 seconds, the slowest fireball ever seen by the observer!
Note: the OASI fireball camera recorded this fireball and another at 18:45 UT the same evening.
Path: due north to due west at an altitude of 20°. The path undulated.
Path: from east to west. The passage of the meteor lasted approximately 10 seconds.
Colour: orangish-reddish, with no fragmentation.
Sound: the meteor generated a whistling, rumbling sound.
The text below is a summary of the full description of the camera and its results, which may be downloaded here.
In May 1976, OASI purchased, from a member of the Society, a second-hand Zorki 4 camera with an auxiliary lens which screwed on to the front of a normal 50 mm lens giving a fisheye equivalent to about a 15 mm lens. The arrangement produced circular photographs that covered the sky from horizon to horizon, but reduced the speed of the optical system so much that it captured only very bright meteors (fireballs). Although the auxiliary lens was slightly damaged it nevertheless provided a reasonable image and it was with considerable interest that members of OASI used the camera to photograph the sky.
After some tentative experimentation and a rather poor response from the BAA Meteor Section, in 1978 OASI passed the camera to Alan Smith to run on a regular basis. After cleaning and testing the camera and auxiliary lens Alan used the auxiliary lens on the front of his own Zenith B SLR camera. The camera was mounted in a wooden box (an old mantle clock case!) with a hole cut in the side through which the lens protruded. This home-made fireball camera recorded its first film on 18 September 1978. Alan sent the film to the BAA Meteor Section and a prompt reply encouraged him to become a regular member of the fireball camera network of Great Britain. He subsequently ran the camera on every clear (or partly clear) night for a couple of years, with each exposure being about 30 minutes, from the end of astronomical twilight to around midnight (when he went to bed!) Eventually, he mounted two resistors, powered from a 12 volt supply, to act as a dew heater. However, every so often, it would rain and the camera would get soaked!
By September 1980, continual requests for feedback from the BAA on reports and photographs had gone unanswered. Alan became disillusioned with the inefficiency of the Association and decided to develop the films himself and report the results directly to the British Meteor Society (of which he was a member).
Eventually he purchased his own wide angle (20 mm) lens which gave a much better and faster image, and in 1980 returned the original auxiliary lens to OASI's instrument curator. However, the camera would still record only very bright meteors.
In March 1981, he fitted a rotating shutter (a set of "helicopter" blades) in front of the lens, driven by an old cassette tape motor. This gave any fast-moving object a dashed appearance on the negative and allowed the speed of fireballs to be estimated and, as a by-product, reduced the amount of background fogging caused by terrestrial lighting. The dashed line image produced on the film was also much easier to spot when scanning the negatives using a high-powered viewer.
Also in March 1981, Alan purchased a motor-driven camera body for less than £20 from a camera shop in Ipswich. He used this to automate operation of the system, so that it would start and stop filming at pre-determined times of the night allowing more exposures to be taken, especially after after midnight. He also constructed a moisture detector which operated a cover to protect the instrument in case of rain. He ran the new camera every clear-ish night until mid-1986.
In early 1981, the camera recorded its first confirmed fireball (confirmed by Dr Keith Hindley, co-ordinator of the fireball camera network). By late 1982, after its first four years of use, the camera had logged 830 photographs over a total observing period of 1475 hours, 53 minutes, 23 seconds, and recorded five fireballs. Statistically, a fireball is expected every approximately 400 hours on average so to capture five in almost 1476 hours was lucky!
By the mid-1980s, despite ongoing improvements to the camera system, its deficiencies were becoming all too evident. The main drawbacks of the fisheye lens for all-sky photography were that the camera was photographically slow and the image size was small. In fact, the camera could capture only bright objects, magnitude -3 and brighter. Other problems associated with the camera concerned the quantity of film used, the quality of film processing, and the hundreds of negatives which had to be examined. Alan scanned the negatives by hand at very high magnification - recall that this was the era before powerful home computers and image processing within reach of all! Eventually, he obtained a microfiche reader that displayed the negative on a glass screen, but the magnification was of necessity very high and visual scanning remained time-consuming as he had to examine every part of every negative. Most negatives of course showed nothing, and even those that did show a meteor trail usually revealed only a very small, faint image. Despite investigating the possibilities of constructing a more sophisticated system based on new optics, Alan stopped running the camera in 1986, as the night sky was by then so light polluted that exposure times had to be curtailed. (The increasing number of aircraft vapour trails compounded the problems of light pollution.)
Alan logged all photos but the passage of time has resulted in the loss of most images. Altogether, he recorded several thousand hours of observation, and created a great number of negatives. One of his regrets was dumping all the negatives - so he had no record of the sky during the supposed "Rendlesham UFO" incident on 26 December 1980.
Some of the best images produced by the camera are below.
Historical footnote on meteor observing in Suffolk.
Reports of OASI meteor watches.