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Notable Meteors and Fireballs : 2017 July-August

Here, in reverse chronological order, is a summary of notable meteors and fireballs reported to the section during July and August

 

2017 Aug 31st  20:30:50 GMT (21:30:50 BST)

Daniel Onan (Milton Keynes) has reported his sighting of this fireball. The fireball was of magnitude about -5 and travelled from hois NNW sky towards the SE, descending from around 58 deg altitude to 32 deg altitude as it did so. If had a duration of 1-2 seconds and left a short-lived long train.

 

2017 Aug 31st  10:31 UT (04:31 local time)

This summary usually only covers fireballs seen from the British Isles, but an exception is made here for regular section contributor Tom Banks who saw a fireball while in the USA.

Tom saw the fireball from Lily Lake, Colorado (Lat 40.31N, Long 105.54 W).  It was around magnitude -6, had a duration of 1-2 seconds and was blue in colour. No fragmentation was seen.

It left a train that persisted for more than 60 seconds.

The path of the fireball, as recorded by Tom as it travelled from Sculptor into Cetus is shown on the accompanying map. There are no major meteor showers active in late August, but the path of the fireball is more or less in line with the radiant of the Alpha Aurigid minor shower which peaks on August 31st.

Note that this fireball should not be confused with the more widely publicised and spectacular  "British Columbia fireball", which appeared a few days later.  Details of this latter event can be found  here

 

2017 Aug 15th  21:42 GMT (22:42 BST)

David Hargreaves (Biddulph Moor, N Staffs)  has reported that he witnessed and imaged a Perseid fireball in his north eastern sky that had a duration of 3-4 seconds.

The image shows the fireball starting close to the radiant (Cassiopeia is to the right).

There are several other reports on the IMO website of fireballs around this time seen from various locations across England.

Although David initially recorded the time of his image as 21:55 GMT, this was only approximate and he believes that there is a good chance that the time of his fireball was earlier and so could tie in with a fireball that appeared at approx 21:42 GMT and was imaged by Ray Taylor of the NEMETODE network from East Yorkshire and also by the  Bayfordbury  and   Hemel  cameras of the Univ of Herts all-sky network (in each case, the fireball trail in the linked images appears near the top right).

 

2017 Aug 12th  21:25 GMT (22:25 BST)

Kevin Boyle (Stoke on Trent) has reported his sighting of a Perseid fireball : "Quite an unusual meteor, initially thought it was a sporadic but backtrack strongly suggests it belonged to the Perseids. Quite a fast one, in keeping with the meteor shower, and was heading in a south to south-southeast direction. It left a short-lived smoky trail, lasting no more than a second and the head of the meteor flared up, reaching a magnitude of -5 to -6, exhibiting an unusual 'reddish' hue. It travelled past alongside the collection of Cygnus, roughly from the outskirts of Cepheus to near Lyra. Overall, the meteor lasted no more than 2-3 seconds."

 

2017 August 5th  22:50 GMT (23:50 BST)

Bill Ward has posted a very interesting video showing the persistent train left behind by a very bright Perseid meteor.

The video can be viewed via this this link

Bill refers to the emission being due to a "forbidden" spectral line. This means that the transition between the atom's energy levels is one that can only be produced in the low density of the upper layer's of the Earth's atmosphere. Such transitions are not produced in oxygen atoms at lower altitudes because the higher atmospheric density results in the oxygen colliding with another atom before the "forbidden" transition has the chance to take place.

 

2017 July 30th  23:36 GMT (00:36 BST on July 31st)

This fireball was imaged by Alex Pratt (Leeds) via his north west facing camera.

Alex notes it to have been of magnitude -4 and possibly a Perseid.

During July, Alex reports that his automated video cameras recorded many meteors, including 62 Perseids, 28 Alpha Capricornids and 35 southern Delta Aquarids.

The Perseids included a mag -2 event at 03:04 UT on July 28 and another mag -2 event at 00:16 UT on July 29.

Early August brought a mag -2.5 Alpha Capricornid at 00:03 UT on Aug 1.

 

 

 

 

2017 July 28th  00:17 GMT (01:17 BST)

The start of this fireball was imaged by Richard Fleet (Wilcot, Hants) low in his northern sky.

Alex Pratt reports that the fireball was also imaged low in the north north west by Nick James (Chelmsford, Essex).

Their analysis of the two images suggests that the fireball had an atmospheric trajectory near the England-Scotland border and was heading in a south westerly direction, as can be seen in the accompanying diagram.

Obviously there is some uncertainty in the trajectory due to the fireball being very distant from the two cameras.

The fireball was probably about magnitude -5.

 

Unfortunately, it seems that all cameras closer to the ground track were clouded our at the time.

 

 

2017 July 23rd  01:30 GMT (02:30 BST)

This fireball was witnessed by Richard Blass (Kilmichael Glassary, rural Argyll).

Richard describes it as being orange in colour, slow moving and having a duration of 3-4 seconds. It was high in the sky, travelling from NNE to WNW. No fragmentation was seen and it didn't leave a persistent train.

 

2017 July 17th  00:43 GMT (01:43 BST)

This fireball was imaged by three cameras of the NEMETODE video camera network.

William Stewart analysed the sky paths and speeds recorded by the individual cameras and determined that its atmospheric trajectory was over the southern Pennines/northern Peak District, as can be seen in the accompanying map.

William added "The meteoroid had a relatively low geocentric velocity (14.1km/s) and hence must have been of a reasonable size to produce a meteor this bright. Calculations suggest an object of circa 300g with a diameter of around 50mm penetrating to an altitude of just under 30km."

The fireball was probably around magnitude -4.

 

2017 July 9th  22:52 GMT (23:52 BST)

This fireball was reported by Neil Fraser (Faringdon, south Oxfordshire). It was in his north eastern sky, had a duration of 1-2 seconds, left a train approx 30 degrees in length that persisted for 0.5 seconds and ended with a terminal flare.

The fireball was also witnessed by three other observers who submitted reports to the IMO. Two were elsewhere in Oxfordshire and one witness was in Kent. Taking into account the sky directions reported from each location would suggest that the fireball's atmospheric trajectory was over the east midlands and it was heading a roughly northerly direction.

Added by:  Tracie Heywood