Always the summer’s main attraction for meteor observers, this August’s display of the Perseid meteors should be quite favourable given that the peak occurs just a few days before new Moon. Consequently, there will be only slight interference from the waning crescent Moon (on the Taurus/Gemini border) just before dawn.
Credit: Peter Meadows - Bright Perseid on 4th August 2012
It is hoped that observers will make every effort to cover the peak of the shower well this year. Meteor observing is a particularly good activity for local societies and the BAA Meteor Section welcomes reports from such groups.
Experienced observers have already reported early activity from the Perseid shower. Peter Meadows and Nick James managed to capture a nice bright Perseid (displaying in-flight and terminal bursts) with their video imaging systems on Saturday, 4th August at 23:56 UT. (See pictures)
When to Observe
Perseid rates normally take a marked ‘kick’ upwards around August 8, and with the Moon now on the wane, watches may be carried out in darkening skies from now right through until the end of the shower’s normal period of activity on August 20, a few days after New Moon. It is hoped that, weather permitting, observers will cover shower activity throughout this period, even on nights away from the maximum.
Credit: Pete Lawrence, 2009
The Perseids are expected to peak around 10h UT on Sunday, August 12, making the late evening and pre-dawn hours of August 11/12 and the following night of August 12/13 probably the most productive for observers in the UK this year. Good observed rates may also be expected in the early morning hours on August 10/11 and 13/14 as the shower radiant (RA 03h 04m Dec +58o) climbs high into the eastern sky. Perseid shower activity will be starting to decline by the time darkness falls on August 14.
All else being equal, the best observed rates are found when the Perseid radiant – near the ‘Sword Handle’ star cluster on the Perseus-Cassiopeia border – is highest in the sky during the pre-dawn hours. However, even in the early evening (when there will be absolutely no interference from moonlight), the radiant is already at quite a favourable elevation above the horizon.
With cloudless skies, and in a dark viewing site, observers can expect to see between 50 and 70 meteors each hour near the peak. Even in light polluted towns or cities observed rates may still be around ten an hour in the early morning hours when the radiant is high.
Credit: Nick James - Bright Perseid on 4th August 2012
Visual Observations
The BAA’s visual meteor report forms, available as downloads in both PDF and Excel formats, enable observers to record the time of occurrence, apparent magnitude, shower membership (or if sporadic), constellation in which seen, and details of any persistent train or other characteristics, for each meteor seen. Watches should ideally be of an hour’s duration or longer (in multiples of 30 minutes). Observers should also carefully record the observing conditions and the stellar limiting magnitude.
Visual observers are invited to submit their observations electronically, using the new BAA report forms, to meteor@britastro.org.
Credit: Tom Kerss, 2009
Imaging
The Perseids are well known for the abundance of fast, bright meteors close to their maximum. Perseid meteoroids enter the atmosphere at a velocity of 60 km/sec, and the resulting meteors often leave behind persistent ionisation trains.
The large numbers of bright events in the five-day interval centred on Perseid maximum makes this an excellent target for digital imaging, considering the low level of interference from moonlight this year. Conventional film is now the medium of choice for very few observers, with most having made the transition to digital SLR cameras.
With a tripod-mounted camera, lens (usually a wide-angle) at full aperture and a high ISO setting, the observer hopes that a bright meteor will flash through the field of view while the shutter is open. Digital SLRs (DSLRs) are very efficient at collecting background light from the sky, particularly at a setting of ISO 1600, so exposures should generally be kept relatively short – no more than five minutes’ duration in a really dark, rural location, and probably only 10 to 30 seconds from a more typical observing site. With some DSLRs, the camera can be operated using a programmable timer attached to the shutter control to take repeated exposures one after the other for as long as required, provided the battery is fully-charged beforehand.
Such a set up, under good sky conditions, can capture meteors of magnitude 1 and brighter. Ideal aiming directions are about 20-30 degrees to one side of the radiant at 50 degrees altitude above the horizon – Cygnus in the early evening, the Square of Pegasus later in the night, or towards the north celestial pole, for best results.
Images of meteor tails may be emailed to meteor@britastro.org. Image labels should include the name of the imager and the date and time (UT) of the exposure.
Written by John Mason – Section Direcor, Meteor Section
The annual Lyrid meteor shower peaks this weekend on the night of April 21-22 when Earth passes through a stream of debris from Comet C/1861G1 Thatcher. The incoming Lyrid meteoroids have atmospheric entry velocities of 49 km/s, and Lyrid meteors appear swift. A fair proportion are bright, and some leave persistent ionisation trains.
The April Lyrid shower, while relatively modest, brings a welcome upturn in rates for a few nights, particularly around the maximum – this year expected just before dawn on Sunday, April 22 – normally producing observed rates of perhaps 6-8 meteors/hr under the clearest and darkest conditions when the radiant is well up in the sky, corresponding to a corrected Zenithal Hourly Rate (ZHR) around 10. Activity is about this level for 12 hours or so centred on the maximum. At other times, observed Lyrid rates may be only 2-3 meteors/hr.
The best observed Lyrid rates will typically be found after midnight, when the radiant (RA 18h 08m Dec +32°) located some 10 degrees south-west of Vega, near the Lyra/Hercules border, climbs higher in the sky. The radiant elevation approaches a very respectable 66 degrees by 0300 hrs local time.
This year’s peak coincides with a new Moon, so there will be absolutely no interference by moonlight. The promise of a good Lyrid display has prompted NASA to plan an unusual 3D meteor photography experiment combining observations from the ground, a research balloon, and the International Space Station. More details are available on:
http://science.nasa.gov/science-news/science-at-nasa/2012/18apr_lyrids/
Although Lyrid activity is generally rather modest, unmapped filaments of dust laid down by the comet occasionally trigger outbursts in rates – most recently in 1982 when, for a couple of hours, a ZHR around 200 was attained. While there is no expectation of enhanced activity in 2012, the Lyrids have sprung surprises on us in the past, and remain a shower very much worth observing.
John W. Mason, Director, BAA Meteor Section
Many reports are coming in of a bright fireball, visible at about 21:40 UT on Saturday, 3rd March 2012. That night the skies were exceptionally clear over large parts of the UK, and many people had been out observing the nice display of the Moon and planets visible that evening.
Gerard Gilligan of Liverpool AS reported that about 20-30 members who were still at the site of the March Wirral Star Party witnessed the magnificent fireball, which rounded off their very busy and successful evening in spectacular fashion.
Sightings have so far been received over a wide area extending from Scotland down through the Lake District to Merseyside. Many eyewitnesses have reported that the fireball was clearly fragmenting towards the end of the track. Observations of this fireball from locations on the eastern side of the Pennines would be particulary useful.
Any BAA members who saw this event, or who may have been contacted by non-astronomers who witnessed it, are asked to collect as much information about the sighting as possible and send it either to the BAA Meteor Section’s Fireball Co-ordinator Len Entwisle at len.entwisle@btinternet.com or to meteor@britastro.org.
Useful information will include the name and location of the observer, the precise time of the event, the altitude and azimuth of the start and end points of the visible track, the position of the observed track against the background stars (or in relation to the waxing gibbous Moon and Mars in the sky, if seen towards the south-east), and a description of the fireball’s visual appearance, colour, etc. together with any unusual features.
It is clear from some of the reports in the national news media that there were other bright meteors visible during the evening of Saturday, 3rd March, but this appeal relates particularly to the event occurring at about 21.40 UT.
Sky & Telescope illustration
The Geminid meteor shower is now underway, with peak activity expected during Wednesday, 14th December. Unfortunately, weather forecasts indicate very variable observing conditions across the British Isles and Northern Europe, so it is important to have a good geographical spread of observers to ensure adequate coverage. The waning gibbous Moon will also be rather obtrusive, so observers are advised to direct their gaze away from the Moon, or to hide the Moon behind an obstruction such as the wall of a house.
The Geminids are currently the most active of the regular annual showers, with rates outstripping those of the Perseids for a 24-hour interval centred on their 14-15 December maximum – a real treat for observers prepared to brave the cold, damp and windy weather.
This year, Geminid activity is expected to peak at about 14h on Wednesday, December 14th, when the peak Geminid Zenithal Hourly Rate may reach 140 m/h – sadly during daylight hours for observers across Europe. The maximum is broad, however, and it is important to have a spread of observers making observations throughout the nights of 13th/14th December and on 14th/15th December to ensure adequate coverage of the shower maximum. In addition, observations by BAA members in North America and the Far East will be welcomed by the Meteor Section to improve coverage of the period of peak shower activity.
The Geminid radiant (at RA 07h 32m Dec +33o, just north of Castor) rises early on and reaches a respectable altitude well before midnight, so observers who are unable to stay up late can still contribute very useful watches. On the evening of Wednesday 14th December there is the added bonus of an increased proportional abundance of bright events after maximum; past observations show that bright Geminids become more numerous some hours after the rates have peaked, a consequence of particle-sorting in the meteor stream.
Geminid meteors enter the atmosphere at a relatively slow 35 km/sec, and thanks to their robust (presumably rocky/asteroidal as opposed to dusty/cometary) nature tend to last longer than most in luminous flight. Unlike swift Perseid or Orionid meteors, which last only a couple of tenths of a second, Geminids may be visible for a second or longer, sometimes appearing to fragment into a train of ‘blobs’. Their relatively low speed and the abundance of bright events makes the Geminids a prime target for imaging.
For further information, or copies of report forms, observing notes, and details of how to carry out group meteor watches, please visit the BAA Meteor Section website at http://britastro.org/meteor
Observations by BAA members and by non-members who have so far communicated with the Director of the Meteor Section confirm that a short-lived outburst of Draconid meteors occurred on 2011 October 8.
Draconid rates were generally low until around 1900 UT on October 8 when a rapid increase in activity occurred, peaking between 2005 and 2015 UT. Thereafter there was a rapid decline, with Draconid meteor rates returning to a low level by 2130 UT. A very preliminary analysis of visual observations made by a group of observers led by the Director, observing from near Goreme in central Turkey, indicates that the peak equivalent ZHR was about 350 m/h between 2005 and 2015 UT, although correction factors are high due to the effect of bright moonlight. It is possible that lesser, short-lived secondary bursts in Draconid activity were also noted around 1915 and 1938 UT.
Observers in the UK had to contend with cloud and rain on the evening of October 8, but it is extremely encouraging that so many individuals and local society groups battled the elements in the hope of getting a view of the shower. Some were rewarded for their persistence. A short period of partially clear weather enabled observers in Dorset, Wiltshire, Oxfordshire, Gloucestershire and Berkshire (and hopefully other areas as well) to glimpse the shower between 1955 and 2030 UT. By a fortunate circumstance this was coincident with the main peak in Draconid activity.
The Director is extremely grateful to all those observers in the UK who have so far communicated with him by email, including: Len Entwisle, Peter Gill (Eastbourne AS), Gerard Gilligan (Liverpool AS), Tim Haymes (Maidenhead AS), Brian Heath (Nottingham AS), Nick James, Gordon MacLeod, Bob Mizon, Alex Pratt, George Spalding and David Swain.
More observations of the Draconid outburst, using photographic, visual, and radio techniques, from individuals and groups in the UK and overseas, are urgently required to build up a full picture of the shower’s rapidly changing activity. Even if you have only glimpsed a few meteors during a short-lived break in the clouds, the Section would like to receive your report. Simple counts of meteors seen within given time periods will also be welcome. It is intended that a summary of all the observations received, crediting all of the individual observers and society groups, will be published in the BAA Journal as soon as all observations have been received and the analysis completed.
There must be many observers – including many non BAA members – who witnessed the peak of the shower, and we would like to encourage all these people to submit their observations to the Section, either via email to:
meteor@britastro.org
or by post to:
Draconid Meteor Project 2011
British Astronomical Association
Burlington House
Piccadilly
London W1J 0DU
There is the possibility of an unusual outburst of Draconid meteors on the evening of Saturday, 8 October 2011. The meteors are connected with periodic comet 21P/Giacobini-Zinner, so the shower is also known as the Giacobinids.
The Earth intersects a number of dust trails laid down by the parent comet during the evening of 8 October.
The first and most probably weaker outburst, due to a number of rather old trails, is likely to occur sometime after 16h UT, but the timing is uncertain and will favour observers in Eastern Europe and the Middle East.
A second and more likely stronger outburst is possible sometime between 19h and 21h UT but the outburst, if it occurs, is likely to be sharp and brief.
Observations across all longitudes are important, but it will be essential for would-be observers to be far enough north to ensure that the radiant is at a respectable altitude above the horizon at that time.
The peak rates of these outbursts are highly uncertain, and no meteor storm is likely. Estimated peak levels of meteor activity range from 40 meteors per hour to 800 meteors per hour. The only way to find out what happens is to go out and look for yourself!
Unfortunately, there will be a waxing gibbous Moon in Aquarius, less than four days from full at the time of peak Draconid activity, so there will some interference from moonlight. Observers should look to the northern half of the sky, keeping the Moon behind them.
The radiant of the shower will be near the star Nu Draconis in the ‘head’of Draco. Draconid meteors are typically very slow moving, in marked contrast to members of showers such as the Perseids or Leonids.
From the British Isles, observers should go out as soon as twilight falls on the evening of Saturday, 8 October.
Observations will also be of considerable value on the evenings immediately before and after the predicted peak to provide a check on background meteor rates at this time. Let’s hope for clear skies everywhere on the evenings of 7, 8 and 9 October 2011, but particularly on the 8th!
The BAA Meteor Section would welcome any observations of the Draconid meteor shower this year from individuals or local society groups, using any of the observing methods outlined on the BAA website. Visit our Draconid Meteor Project page’. Even simple counts of meteors seen within given time periods will be welcome.
It is intended that a summary of all the observations received, crediting all of the individual observers and society groups, will be published in the BAA Journal as soon as possible after the event.
Although the Perseids are one of the stand-out meteor showers of the year, in 2011 the display is unlikely to be spectacular due to the interference of the full Moon. The maximum of the shower is predicted for around 06:00 UT on August 13th, with the Full Moon later that day. The brightness of the Moon means that the sky in general will be a lot brighter too, and so only the brightest of the meteors is likely to be seen.
But this does not mean that it won’t be worth observing, but it is best to try and choose an observing spot that maximises your chances. Try to find a place with the Moon behind, preferably shaded by a building, tree or hill.
Its not really possible to say where in the sky to look, because the meteors can appear from anywhere. If you trace the path of the meteor, you should find that it appears to originate from the constellation of Perseus (this is why this shower is known as the Perseids), if it is a Perseid. Perseus will be rising in the north-east around midnight, and so just before midnight and through to dawn is the best time to view.
The radiant of the Perseids - illustration from Sky and Telescope
For those carrying out a meteor watch, you can download BAA Observing Report Forms as PDF or Excel files. And you can find out about how to observe and record observations on the BAA Meteor Section website. Please send your observations to the Meteor Section Director, John Mason.
So whilst this may not be a vintage year, do try to observe when you can, and report your observations back to the BAA.
The New Year opens with very favourable conditions for the Quadrantids, one of the three most active regular annual showers.
Active from January 1-6, the Quadrantids have been poorly observed in most recent years thanks to a combination of factors – a very narrow period of high activity, poor January weather, and moonlight interference in at least one year out of three!
However, when the shower was last well-covered by BAA observers, a peak ZHR of 100-120 m/h was found. Unfortunately, activity is close to peak levels for only about six hours: at other times, only a ‘trickle’ of a few meteor per hour might be detected.
The Quadrantid radiant (RA 15h 28m Dec +50o) actually lies in northern Boötes (in a region occupied by the now defunct constellation of Quadrans Muralis), and from the latitudes of the British Isles it is circumpolar.
Timing of the Quadrantid peak in January 2011 is quite favourable from the UK perspective, especially as the peak coincides with new Moon, so there will a complete absence of interference from moonlight. The shower maximum is expected around Jan 04d 00h UT, midnight at our longitudes. Although the radiant is rather low in the northern sky during the evening hours, it will be rising higher by midnight and it climbs to a very favourable elevation as dawn approaches. Observations in the hours after midnight on January 3/4 will be the most productive.
Local Time Radiant Altitude Local Time Radiant Altitude
(Lat. 53oN)
(Lat. 53oN)
17 22.5o 00 21.8o
18 18.1o 01 27.2o
19 14.9o 02 33.3o
20 13.3o 03 41.8o
21 13.1o 04 49.0o
22 14.6o 05 56.9o
23 17.5o 06 66.3o
Much of the high activity close to the peak is comprised of moderately bright to faint meteors. As a result of particle-sorting, brighter Quadrantids (produced by larger meteoroids) become more numerous following the maximum, and this might be evident by dawn on January 4. Quadrantids are, like the Geminids, relatively slow meteors, with an atmospheric entry velocity of 42 km/sec. The brighter shower members are sometimes strongly coloured (often blue or green).
The stream’s dynamic orbital history – much perturbed by Jupiter’s gravity – has made identification of its parent body complicated. Recent studies have suggested that the Quadrantids may be debris from asteroid 2003EH1 (another similarity with the Geminids!), a possible break-up product of Comet 1490Y1 following the latter’s close approach to Jupiter in 1650.
The Quadrantids can certainly be listed as a shower very much in need of observation – so why not make it your New Year’s Resolution to start 2011 with a few hours of meteor watching between midnight and dawn on January 4.
And, observers who have been out Quadrantid watching during the early morning hours of January 4 can reward themselves with a most interesting partial eclipse of the Sun at sunrise that morning.
Additional information about the Quadrantid meteor shower is given in the ‘Notes and News’ section of the December BAA Journal.
For further details, or copies of report forms, observing notes, and details of how to carry out group meteor watches, please visit the BAA Meteor Section website at http://britastro.org/meteor
John Mason
Acting Director, BAA Meteor Section
Picture of the Week: Perseids
Perseids
A composite photo of Cassiopeia taken overnight on 12-13th Aug from Whitstable, UK, by John Kemp. It shows 10 Perseids and a faint sporadic (top left) – or possibly as many as 3 are sporadics.
Ten shots showing meteors and 19 background shots with no meteors were combined, selected from several hundred 30 sec exposures made beteen 10.45pm and 3.45 am: KonicaMinolta Dynax 5D DSLR, 400 ISO, 50mm f/1.8 lens, tracked to maintain field of view over the hours. Processed in DeepSkyStacker and Photoshop.
John says: “Big learning curve to produce this! I’ve tried to be as faithful as I could to the data but can guarantee only aproximate photometric consistency accross the whole field of view, as some of the meteors were against thin cloud, and I’ve had to remove the cloudglow as best I could.”
Image of a Perseid
A Perseid, by Pete Lawrence
An image of a Perseid meteor taken during the 2009 shower. The meteor appears as a bright streak running from top centre to bottom right. The stars of the constellation of Cygnus and the Milky Way are visible on its the left and the bright star Vega can be seen on its right. Credit: Pete Lawrence (click on image for hi-res version).
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