Bill Ward has continued to work on the images that he captured during his trip to Tenerife to monitor the maximum of the 2017 Geminids Read more
Following on from his mammoth effort during the night of Dec 11-12, Tom Banks (Comberbatch, Cheshire) made use of a couple of cloud breaks during Geminid maximum night (Dec 13-14) to spot some Geminids. His first session, between 22:36 and 22:53 UT (50% cloud, increasing to 100%) produced 6 Geminids, while a second session at the end of the night from 06:23 to 07:27 UT (LM 5.0, significant cloud issues 06:33-06:45, twilight at end) produced 16 Geminids and 1 sporadic.
A further meteor watch by Tom during the night of Dec 15-16, illustrated how rapidly Geminid rates fall away in the nights following maximum. During observations totalling 5 hours 15 minutes (LM 5.3), he recorded 16 meteors, of which just 7 were Geminids.
Alastair McBeath (Morpeth, Northumberland) had longer clearer spells during the night of Dec 13-14. Observing from 22:39 to 02:46 UT (LM 6.1, around 50 minutes lost to cloud), he saw a total of 202 Geminids and 31 sporadics. Six of the Geminids were in the fireball category, though none were brighter than magnitude -4. One of Alastair’s fireballs (at 01:59 UT, travelling from Canis Minor to close to Sirius) may tie in with a fireball imaged low in the NW sky by the Bayfordbury camera of the University of Hertfordshire. His other fireballs were seen at 22:57 (Ori), 23:29 (Eri), 02:22 (UMa to Dra), 02:27 (Tau) and 02:44 UT (UMa).
Brendan Shaw (Meshaw, north Devon) observed between 22:49 and 00:35 UT (LM 5.5) during the night of Dec 11-12 in mostly clear skies, seeing 12 Geminids and 1 sporadic. The best meteor was the first – a mag -2 Geminid at 22:51 UT. He also noted two Geminids appearing only 20 seconds apart at 23:54 UT.
Robin Scagell (Flackwell Heath, Bucks) observed between 01:11 and 02:11 UT (LM ~4.5, passing cloud at times, 5 mins lost due to camera adjustment) on the morning of Dec 14, seeing 33 Geminids and 4 sporadics. the brightest meteors (6 Geminids and 1 sporadic) were of magnitude -2. Robin also imaged 6 Geminids in a total of 219 20-second exposures using a Canon 70D camera with 17 mm f/2.8 Sigma lens at ISO 3200.
Robin’s wife Sally, a less experienced observer, monitored a different part of the sky between 01:25 and 02:11 UT, seeing 25 meteors which were probably all Geminids.
Pam Foster (Pitlochry) observed from indoors between 19:40 and 00:40 UT (4 hours observing) on Dec 13-14 and, despite increasing problems with cloud during the final 80 minutes, saw 102 meteors.
Richard Fleet (Wilcot, Hants) reported seeing 5 meteors in good skies, between 23h and 0h UT on Dec 15-16, with just one being a Geminid, once again illustrating the rapid fall off in rates post-maximum.
The sharp fall-off in Geminid ZHRs can also be seen in the IMO Geminid activity graph
Bill Ward has now returned from his trip to Tenerife, where was was rewarded with three clear nights adding
“Peak ZHR comes in at 128 +/- 11, (03-04 ut on 14th) smashing the 2012 record. Some incredible images and spectra!” .
One of his images is reproduced here and shows a bright Geminid that ended behind a mountain.
One of Bill’s Tweets has led to some interesting debate between experienced meteor observers.
The image is reproduced here and shows a Geminid that appears to have a rather wavy path.
The subsequent Twitter discussions have focussed on two questions:
– whether some meteors do show “corkscrew”-like motion – some visual observers have in the past reported seeing such effects, but this has been difficult to verify due to the lack of a permanent record.
– whether the wavy motion seen in this image was a genuine property of the meteor or could have been due to the camera being shaken by the wind or the workings of the camera (“mirror slap” has been suggested).
The Twitter discussion can be viewed here
with more discussion here
Bill has also posted this time lapse video showing 29 meteors that he recorded close to the Geminid activity peak from Tenerife. It is certainly worth waiting for the event 1:10 into the video !
Here are three additional Geminid images that were captured by Alex Pratt (Leeds) during the night of Geminid maximum (Dec 13-14).
Observing conditions were not ideal, but Alex commented
“Fortunately I had intermittent clear spells, with frequent gaps in the blanket of clouds. Video cameras can deliver the goods in these circumstances and a number of meteors were recorded through thin cloud or small gaps in the clouds.”
The first image shows a Geminid heading from Gemini towards Orion and was captured via his SE facing video camera at 22:49:27 UT on Dec 13th.
The second image was captured at 03:52:02 UT on Dec 14th via his N facing video camera.
Four stars of the ‘W’ of Cassiopeia can be seen to the left of this meteor.
The fainter streak of light to the left of the meteor is an image artefact and is a consequence of Alex operating this video camera through a window.
The third image was captured via Alex’s NW facing video camera at 05:21:30 UT on Dec 14th.
The cloud in this image would have made life difficult and less rewarding for visual observers, but video cameras “don’t care” and continue to record any meteors that appear through cloud gaps.
Below are four more Geminid images captured by Paul Sutherland (Walmer, Kent) during the night of Dec 13-14.
The times of these meteors were 01:44 UT, 02:20 UT, 02:24 UT and 03:38 UT.
Paul had his camera (Fujifilm X-M1 with Samyang 12mm f2 lens) running from 01.08 UT until 06.35 UT, although twilight was becoming an issue by 06h. He added “The lack of colour in the Geminids is quite noticeable after the colourful bright meteors provided by the Quadrantids, Perseids and Leonids“.
Moonlight circumstances were very favourable for the 2017 Geminids, but would the December weather be cooperative?
Bill Ward reported that he was taking no chances and was setting out for Tenerife with his cameras. Hopefully he will return with lots of nice meteor images.
The Geminid radiant would be above the horizon all night from the UK, with observed rates each night likely to be highest at around 2am
Skies were clear over much of the UK, but with snow on the ground in many areas, coupled with a northerly wind, it was for many the coldest night of the year.
Some hardy observers did brave the conditions to make use of the clear skies.
Tom Banks (Comberbatch, Cheshire) put in an outstanding effort, carrying out three meteor watches that amounted to 7 hours in total. During the first session between 22:16 and 00:16UT, he saw 20 Geminids and 6 sporadics (LM 5.1). The second session between 01:31 and 04:31 UT yielded 14 Geminids and 10 sporadics (LM 5.3), while the final hour-long session between 04:45 and 05:45 UT produced 3 Geminids and 2 sporadics (LM 4.8). Tom’s brightest meteor was a mag -3 Geminid seen in Lynx at 05:07 UT. He also recorded a fast-moving blue-tinged mag -2 meteor at 00:51 UT but although, this appeared to come from the general direction of Gemini, he couldn’t definitely trace it to te radiant and so recorded it as a sporadic. An amazing effort by Tom, who added “I now have a face like a polar explorer from the exposure (-6 degrees) and a perpetual yawn, but it was worth it for seven hours’ worth of records”
Jeff Stevens (Stoke-on-Trent) reported spending an hour, starting at 22:33 UT, lying on his garden bench looking for Geminids (LM ~3.5). He recorded five, including two simultaneous ones at 22:53UT. Jedff added that hs coat had frozen to the bench when he came to get up at the end!
David Scanlan (Romsey, Hants) reported observing for an hour between 18:30 and 19:30 UT (LM 4.5) and seeing one Zeta Aurigid and 1 sporadic, but no Geminids.
Dec 13-14 (maximum night)
Many parts of the UK endured overcast skies, with further snowfall in some areas. However, some observers found the weather to be better than expected and were able to make use of short-lived breaks. In such conditions, it is usually possible for some observers to monitor the meteor activity via radio methods using forward scatter from the GRAVES radar system in France. However, this was not to be as William Stewart reported his disappointment that GRAVES went offline at 20:09 GMT.
Richard Fleet (Wilcot, Hants) observed visually and reported seeing 33 Geminids and 9 other meteors during a clear spell between 11pm and midnight.
Shortly after ending his visual observations, due to a veil of thin cloud spreading across, his SW facing camera captured this image of a bright Geminid.
A late night clearance allowed Richard to observe again, seeing 46 Geminids between 5am and 6am, six of which were mag 0 or brighter.
Jeff Stevens carried out a short meteor watch between 22:40 and 23:40 UT (20 mins with interference from broken cloud), seeing 9 Geminids.
Once early evening cloud had dispersed, David Scanlan was able to observe for 1 hour 22 minutes between 21:43 and 23:05 UT (LM 4.5), seeing 17 meteors, 14 of which were Geminids.
Steve Brown (Stokesley, North Yorkshire), reported via Twitter that during a 4 hour session, starting mid evening, he recorded 101 Geminids, 15 sporadics and 1 owl.
Alex Pratt (Leeds) had intermittent clearer spells along with a number of smaller cloud gaps – conditions that are challenging for visual observers but which hinder video observing much less.
He has reported imaging around 800 events, with around 500 likely to be Geminids.
His best event was the mag -4 Geminid at 23:30 UT, shown in the accompanying image, that was recorded by his NW facing camera.
Other notable events that were imaged by Alex included those at 22:48 UT, 03:52 UT and 05:21 UT.
Paul Sutherland (Walmer, Kent) and Stuart Atkinson (Cumbria) reported their results from the early hours of the 14th via Facebook.
Paul’s images were captured via his automated camera system (Fujifilm X-M1 with Samyang 12mm f2 lens). Over a 5 hour interval, Paul captured images of 48 meteors. Stuart reported seeing around a couple of dozen Geminids visually in around 40 minutes and imaging three of them.
Paul’s best image, from 01:38 UT, is shown below left, with Stuart’s best image on the right
Congratulations go to the SPA’s Paul Sutherland whose image of a Leonid fireball from 2017 Nov 19th was chosen to appear on the “cover” of the 2018 January issue of the on-line magazine eMeteorNews. Read more
October Camelopardalids: A minor meteor shower that has occasionally produce good observed rates, including in 2016.
|Main Activity Dates||Oct 5 – 6|
|Peak Rates||Oct 5d 18h-22h ?|
|Best Observed Rates||Oct 5|
|Visibility each night (UK)||Visible all night|
|Moonlight issues at Maximum||Serious – Full Moon is on Oct 5|
Draconid (Giacobinids): Can produce very high rates when parent comet is near perihelion – 2017 is not such a year
|Main Activity Dates||Oct 7-10|
|Peak Rates||Oct 8 – 9|
|Best Observed Rates||Evening of Oct 8|
|Visibility each night (UK)||Visible all night|
|Moonlight issues at Maximum||Very Significant – Full Moon is on Oct 5|
These are two low activity meteor showers that occasionally do something “interesting”.
A significant level of activity from the October Camelopardalids was reported by video observers in 2005 and 2006. Another outburst was recorded in 2016, between 14h and 15h UT on Oct 5th (for further info, see here ).
No significant activity was seen in other years. A recurrence in 2017 of the 2016 event would most likely peak some time between 19h and 20h UT on Oct 5, favouring observers in western Asia.
The October Camelopardalid radiant, at approx RA 11h, Dec +78, is located roughly midway between the pointers (alpha and beta UMa) and Polaris, as is shown in the accompanying chart.
Unfortunately for visual observers, moonlight will be a serious problem in 2017, with Full Moon occurring on Oct 5. Video observers should, however, be less seroiusly affected.
The Draconids, also known as the Giacobinids (due to their link with Comet 21P/Giacobini-Zinner), produced meteor storms in 1933 and 1946, along with strong activity in 1985,1998 and 2011. However in most years very little activity is seen and 2017, with the parent comet still in the outer part of its orbit, is expected to be such a case. The next potentially good year will be 2018.
The Draconid radiant, at RA 17h28m, Dec +54, lies just to the right of the head of Draco (see the chart below). Draconid meteors are slow moving – a feature that should allow them to be readily distinguished from any sporadic meteors that might by chance line up with the Draconid radiant.
From the UK, the Draconid radiant is above the horizon all night and is highest in the sky during the early evening hours.
Moonlight will significantly affect Draconid observations in 2017, with Full Moon havig occurred on Oct 5.
Alpha Aurigids A minor meteor shower that occasionally produces stronger displays
|Main Activity Dates||Aug 25 to Sep 10|
|Peak Rates||Aug 31|
|Best Observed Rates||Late in the night of Aug 31 – Sep 1|
|Visibility each night (UK)||Visible all night, but radiant is low in sky before midnight|
|Moonlight issues at Maximum||minor – waxing gibbous Moon in Sagittarius|
September (Epsilon Perseids) A minor meteor shower that produced a somewhat stronger display in 2013
|Main Activity Dates||Sep 5 – 21|
|Peak Rates||Sep 9|
|Best Observed Rates||Late in the night of Sep 9-10|
|Visibility each night (UK)||Visible all night, but radiant is low in sky before midnight|
|Moonlight issues at Maximum||Severe – waning gibbous Moon in Pisces|
September is often overlooked by many meteor observers due to there being no major meteor showers active. However, it is around this time of the year that sporadic background activity peaks and a number of minor meteor showers are also active.
The Alpha Aurigids start in August and peak at the August/September transition. Moonlight circumstances are fairly good in 2017. Despite the Moon having passed first quarter on Aug 29, it will be low in the sky in Sagittarius on the night of maximum and setting by around midnight, leaving the sky moon-free for when Auriga has become higher in the sky. Dramatic enhancements of Alpha Aurigid activity have been seen in some years, but none are predicted for 2017. This chart shows the radiant location, with the UK horizon shown for the early hours of the morning – note that the radiant is closer to Delta Aurigae than to Alpha Aurigae (Capella):
The September Perseids (sometimes referred to as the Epsilon Perseids) peak around the 9th of the month. The shower is properly observable from the UK by 22h UT, and can be watched thereafter all night. A stronger than usual display from this shower was detected in 2013. A Full Moon restricted observations in 2014, but nothing unusual was reported. Similarly, nothing unusual occurred in 2015 or 2016. Moonlight circumstances are poor in 2017. Full Moonoccurs on Sep 6 and by the night of maximum the gibbous Moon in Pisces) will be rising soon after it gets dark.
This chart shows the radiant location, with the UK horizon shown for the middle of the night. Note that at maximum the radiant lies close to Beta Persei (Algol) rather than Epsilon Persei.
Later in the month we start to see the start of activity associated with numerous meteoroid trails left behind over the millennia by comet Encke. Indeed, from mid September the IMO lists the Southern Taurid shower, rather than listing the more general Antihelion source in its shower listing.
|Main Activity Dates||August 3-25|
|Peak Rates||around Aug 18th|
|Best Observed Rates||around the middle of the night|
|Visibility each night (UK)||Visible all night|
|Moonlight issues at Maximum||None – New Moon is on August 21|
Although some kappa Cygnid activity will be seen by observers in the lead up to Perseid maximum, the peak of this minor shower occurs in mid August, probably around August 18th.
Rates are generally low and meteors are slow, but occasional bright fireballs (possibly in periodic bursts every 6 to 7 years) have been seen from this source. There are also suggestiojns of a decades-long periodicity in rates.
Interestingly, the shower shows up rather strongly in the radar monitoring of the CMOR system , indicating that there is also a significant contribution from small particles that are too faint to be readily seen with the naked eye.
New Moon in 2017 is on Aug 21. Hence moonlight will not be a problem for the peak of the 2017 Kappa Cygnids.
The position of the radiant, on the border of Cygnus and Draco, is shown on this chart:
The Quadrantid meteor shower is active during the first week of the year, with peak activity set to occur during the night of Jan 3-4. Read more
Here, in reverse chronological order, is a summary of notable meteors and fireballs reported to the section during December 2017:
2017 December 31st 17:33 UT
This fireball was reported by hundreds of witnesses across the UK.
The accompanying map shows the locations of all witnesses who submitted their reports via the IMO report form http://spa.imo.net/
As the map indicates, most witnesses were on the eastern side of the country,with people further west missing out due to vercast skies.
The preliminary analysis by the International Meteor Organisation (IMO) indicate that it started over the North Sea and travelled westwards, crossing the coast near Hartlepool and ending to the south of Carlisle.
This trajectory is shown by the blue arrow on the map.
More details can be found in this report
Bill Ward initiated an interesting on-line discussion after posting an image of a Geminid meteor with a wavy path that he captured during a trip to Tenerife to monitor the maximum of the 2017 Geminids. Bill noted that he had imaged 10 such meteors during this trip and one during an earlier trip, but hadn’t imaged any from the UK in the past.
Over the years, some visual observers have reported seeing meteors that appeared to have non-linear paths, but in the absence of photographic evidence, there was no way to establish whether the meteor’s path was really non-linear.
Some of the comments in response to the post did suggest, however, that the wavy-ness might have been due to motion of the camera (possibly related to the wind) or an effect known as “mirror slap”. The reason that the effect was only seen from Tenerife might therefore be a consequence of airline baggage restrictions meaning that the tripod used might not have been as sturdy as that used in the UK.
If this “corkscrewing” is genuine, then the only way to prove it will require the same meteor to be imaged from more than one location.
Other Notable Geminids
Although visual observers commented on the lack of particularly bright Geminids, some fireballs were imaged.
Alex Pratt (Leeds) commented that on a number of occasions he recorded pairs of simultaneous Geminids, one such pair being that in the accompanying image, captured at 00:36:53 UT on Dec 14th via his N facing camera.
2017 December 7th 21:07 UT
This fireball was reported by Mark Garrett (Compton Dando, Somerset) and Iain Sainsbury (Great Abington, Cambridgeshire).
Mark saw the fireball in his eastern sky and reports that it started in Gemini and ended near Betelgeuse, adding “the fireball stretched out creating a tail and the tail split into three parts (gaps appeared)” . From Iain’s location, the fireball started in the east and ended in the SSW. Iain described it as been yellow and orange in colour and leaving a persistent train, adding “As I watched it it broke up into 10-20 pieces some larger an others maybe 6-7 big pieces“.
There was a good deal of cloud over the UK at the time and this no doubt limited the number of witnesses. The IMO received additional reports from witnesses in Lancashire, Oxfordshire and Essex and, taking into account the sky positions reported from each location, have derived a provisional trajectory for the fireball, starting over Norfolk, near Norwich, and heading in a SW direction, ending close to London. This trajectory, does however, appear a little inconsistent with the two SPA reports as, based on these, a trajectory shifted further south (Suffolk to Surrey?) would seem more accurate.
Here, in reverse chronological order, are details of notable meteors and fireballs reported to the section during November 2017:
2017 Nov 29th 17:06:42 UT
This fireball in the evening twilight was widely seen.
The image shown here was captured by William Stewart (Ravensmoor, Cheshire) of the NEMETODE network ( http://www.nemetode.org )
Visual reports include the one from Mell Jeffrey (Norton, North Yorkshire). Mell was driving at the time and comments that she initially thought it was just car headlights reflecting off her windscreen, before realising that a reflection from headlights wouldn’t have reflected and moved in such a way. She records the event as starting in her western sky, descending steeply towards the WNW and having a duration of 3-4 seconds.
Many reports of the event were made via Twitter. These reports were inevitably rather brief (e.g. “Did anyone else just see a fireball like a massive shooting star pass across the sky over England?” and “Spotted it in Bolton – spectacular!“, but did give an indication as to which parts of the UK the fireball was seen from – tweets came from locations as far apart as Edinburgh and Essex. Some also illustrate how members of the public react to such events, with comments including “it was incredible to see it, quite spooky” , “I went inside and told my wife, but she looked at me funny” and “I wish some boffin has a photo of it“.
Although the fireball was “detected” by several automated video systems, the number of good images captured proved small. Richard Fleet (Wilcot, Hants) recorded a flash through the clouds via his NW facing video camera at the time of the fireball, while Alex Pratt (Leeds) reported that his NW facing video camera was automatically activated to record a video clip at this time by a flash outside of its field of view.
William Stewart (Ravensmoor, Cheshire) did record the fireball via his all sky camera, as it passed through patchy cloud, with the software he was running classifying it as a member of the December Alpha Draconid minor meteor shower and possibly around magnitude -7. His image is shown above.
William reported the fireball via this tweet , which includes a link to his video of the fireball
Details of all of the reports of this fireball submitted to the IMO can be viewed via this link http://spa.imo.net/imo_view/event/2017/4781
The provisional analysis of the visual reports submitted to the IMO suggested that the fireball was heading in a NW to SE direction and had a ground track over western Cheshire.
William, however, was able to carry out a more detailed analysis, based on the more precise sky positions and speeds provided by his video record and by a second video captured by another NEMETODE member, Nick James (Chelmsford).
This analysis places the ground track slightly further west and over north east Wales. It indicates that the fireball became visible at an altitude of about 95km and ended at an altitude of around 28km.
2017 Nov 29th 02:51 UT
Bill Ward (Kilwinning) reports capturing 325 images during the night of Nov 28-29, although on closer inspection he found that 82 were due to cosmic rays rather than meteors.
His best capture was of an event at 02:51:59 UT for which he captured the second order spectrum shown here.
Bill captured the spectrum using his 600 lines/mm system and notes that he was very close to resolving the magnesium triplet around 5175A.
Bill also comments that the spectrum also showed emission lines from Iron well into the near UV.
2017 Nov 25th 07:13UT
The night of Nov 24-25 proved productive forRichard Fleet (Wilcot, Hants).
In addition to the fireball just before midnight, he imaged another fireball in the morning twilight, just before his automated imaging system was due to switch off.
The slow moving fireball was imaged via his SW facing video camera, from which the accompanying still image is taken.
The video can be viewed here
The fireball was also seen visually by Rob Sime(Rugby), who saw the fireball low in his SSW sky and described the fireball as breaking up into approx 10 pieces and showing green and white colours.
The IMO also received many visual reports of this fireball from witnesses across the southern half of the UK and from NW France.
The reports submitted to the IMO can be viewed here
This map in this link also shows that the most likely ground track for this fireball was in a WSW direction just south of the Dorset coast.
2017 Nov 24th 23:59 UT
This spectacular fireball was seen visually by Adrian Avery (West Sussex) and imaged by Richard Fleet (Wilcot, Hants).
Adrian saw the fireball in his western sky, describing it as “Brilliant Green, appeared to explode (soundlessly) before vanishing”.
Richard imaged it via his SW facing video camera, from which the accompanying still image is taken. The video can be viewed here
The fireball was seen by large numbers of observers across the south of England, observers further north presumably missing out due to cloudy skies.
The reports submitted to the IMO can be viewed here. This summary also marks the most likely ground track for the fireball and suggests that despite Richard’s initial guess that the fireball may have been over the English channel, it may actually have been a little further north and located over southern Hampshire.
2017 Nov 19th 19:55:08 UT
Richard Fleet (Wilcot, Hants) has posted this fireball image that he captured through thin cloud via his SE facing camera.
The fireball was also imaged by another camera of the UKMON network, based at Ash Vale in Surrey.
Intriguingly, a video has also been posted via Twitter by airlivenet of a fireball imaged from Heathrow airport at 20:09 UT. This video bears a timestamp approx 14 minutes later than Richard’s image, but the fireball appears so similar in appearance as to raise the possibility that it shows the same object and that the time discrepancy is due to an error on the video system’s clock.
The video can be viewed via this link
However, there are also several reports to the IMO of a fireball at around 20:10 from four witnesses in the UK and many more in France. These reports can be viewed here . The preliminary IMO analysis indicates that this latter fireball’s trajectory was in a westerly direction over northern France.
2017 Nov 19th 05:47:05 UT
William Stewart (Ravensmoor, Cheshire) captured an image of this Leonid fireball via his SE facing camera. The software recorded its magnitude as about -6, although there is some uncertainty in this due to the presence of thin cloud.
William also reported capturing a spectrum of the fireball and detecting the forward scatter radio reflection from its ionisation trail. Michael O’Connell, another member of the NEMETODE group, also reported detecting the radio reflection from Ireland. Three other NEMETODE members subsequently reported having captured images of this fireball, allowing its atmospheric trajectory to be determined. For further details, see here
2017 Nov 19th 02:29:06 UT
Paul Sutherland (Walmer, Kent) captured this DSLR image of a Leonid fireball as it crossed the constellation of Coma Berenices.
Paul did not see the fireball directly, but the fireball was also recorded by several observers in the Netherlands (see here ) and these reports indicate that it was probably around magnitude -8.
Paul also captured a number of images (included in the 2017 Leonids report ) showing the decay of the fireball’s persistent train, which took more than 10 minutes.
2017 Nov 17th 00:43:42 UT
Bill Ward (Kilwinning, near Glasgow) captured an interesting spectrum of a bright meteor on the morning of Nov 17th. Although this was close to Leonid maximum, Bill originally classified it as a sporadic but, following a more detailed analysis of its path, subsequently re-classified it as a Leonid.
The image shows the first order spectrum – the meteor itself lies outside of the field of view but will have been travelling from left to right and hence the spectrum is fairly vertical. The two brighter spectral lines towards the mid right hand edge of the image are the usual emission lines from magnesium and sodium.
The two brighter “bands” towards the right hand side of the image are due to flares near the end of the meteor’s path.
Although all spectral lines brighten at the position of these flares, Bill notes that three of the fainter lines brighten by a much greater amount than to the other fainter lines.
Bill has identified these three lines as being related to ionisation – and has labelled these lines in the intensity plot.
As can be seen in the plot, these ionised lines are barely detectable in the (lower) plot measured midway along the path of the meteor but are very obvious in the (upper) plot measured at the time of the flare.
Bill notes that this was clearly a fast moving meteor, given that the 557.7nm “forbidden” line of oxygen is briefly visible at the start of the spectrum, this being a spectral line resulting from emission that can only occur at altitudes higher than 110 km. This high speed also fits in with it being a Leonid, the Leonids producing particularly fast meteors.
2017 Nov 13th 04:31:59 UT
Bill Ward (Kilwinning) captured this image of a Leonid fireball on the morning of November 13th. The image shows it moving away from the ‘sickle’ of Leo.
Bill has also posted a video clip which shows the fireball, its associated persistent train and a spectrum of the fireball that contains a number of ‘forbidden’ spectral lines from oxygen, including the green line at 557.7nm.
The video can be viewed here
‘Forbidden’ spectral lines are spectral lines that are not seen under normal conditions near the Earth’s surface, but can be seen in much less dense environments, such as is the case high (above 110km) in the Earth’s atmosphere. Meteor showers, such as the Perseids and Leonids, that produce faster meteors are more likely to be visible at such altitudes.
2017 Nov 12th 18:29 UT
Richard Fleet (Wilcot, Hants) has posted this image of a bright sporadic meteor that he captured via his south east facing video camera during the early evening of Nov 12th.
2017 Nov 7-8
Bill Ward reports capturing spectra of three meteors during this night, each showing its particular characteristics. The colourised synthetic spectra are shown below:
Bill also reports that he has been investigating the feasibility of using liquid crystal “rotating shutters” with his DSLR cameras in order to determione the speeds of imaged objects (and help differentiate between meteors and satellites).
You can read about his results at https://britastro.org/node/11675