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Alastair McBeath
Joined: 23 Jul 2005
Posts: 572
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 Posted: Sat Dec 27, 2008 10:19 am Post subject: Quadrantids 2009 |
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International Year of Astronomy 2009 opens meteorically with a waxing crescent Moon for the Quadrantid maximum, due on January 3, around 13h UT. So, lunar circumstances are very favourable, but the timing is equally poor for the UK, given the shower's typically short, sharp peak - if the prediction proves accurate.
The radiant is circumpolar in northern Boötes, at RA 15h20m, Dec +49°, so is lowest in the early evening and only properly observable after midnight UT. As the Moon will set on January 2-3 before 23h, it is possible we may still see something of the rising activity from the shower in dark skies, particularly in the hours before dawn on January 3.
Maximum Zenithal Hourly Rates (ZHRs) from the Quadrantids have been around 120 in recent times, though the highest value does vary from year to year between roughly 60 to 200, and has occasionally persisted for a couple of hours close to its best level (most recently last year, when the visual peak was also 3 to 4 hours later than expected, with ZHRs of about 80). Other maxima, perhaps of chiefly fainter meteors, have been suspected, or occasionally detected, up to half a day to either side of the visual peak's timing. So, watches could be worthwhile even on January 3-4, if skies are clear, as the Moon then will be setting around, or a little after, midnight for our latitudes. Of course, there are no guarantees!
Quadrantids are medium-speed meteors, often reasonably bright near the visual maximum. Much lower numbers of them should be present from about January 1-5. For more Quadrantid information (including links to news from the 2008 return), and details on the likely minor shower activity in January, see:
http://www.popastro.com/sections/meteor/meteor-jan2009.htm .
Be well-prepared for the probable conditions outdoors, good luck and clear skies!
Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please) |
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andyT
Joined: 13 Feb 2006
Posts: 750
Location: south wales.U.K.
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| Posted: Mon Dec 29, 2008 11:45 am Post subject: |
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Hi Alastair,i'm hoping to get some observing done for this shower.
i hope the weather clears nicely here too.we've had dark clear skies up till today so fingers crossed.
rgds,andy
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david entwistle
Joined: 13 Aug 2006
Posts: 660
Location: Goosnargh, north of Preston, UK
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| Posted: Sat Jan 03, 2009 6:27 am Post subject: Re: Quadrantids 2009 |
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| Alastair McBeath wrote: | The radiant is circumpolar in northern Boötes, at RA 15h20m, Dec +49°, so is lowest in the early evening and only properly observable after midnight UT. As the Moon will set on January 2-3 before 23h, it is possible we may still see something of the rising activity from the shower in dark skies, particularly in the hours before dawn on January 3.
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I hope some of you are getting to see meteors. Unfortunately it has remained overcast here in Lancashire overnight on the 2/3 January 2009.
Radio meteor counts increased rapidly as the Quadrantid radiant rose through the night and into the morning of the 3rd January 2009. My own counts decreased as the radiant passed close to the zenith (an expected peculiarity of radio observation), but recovered later as the radiant moves to a position lower in the sky.
Real-time radio meteor observations are available here.
Real-time radio meteor observations from Japan are available here. Time is reported in UT.
My own results are below:
The following preliminary results from the 2009 Quadrantids are courtesy of Jeff Brower, British Columbia, Canada.
Jeff's data is from a single TV video carrier at Bend, Oregon located 193 degrees to his south. It is running 58.9 kW and is moderate base line distance of 655 km.
Echo counts for -40,-30,-20 dB thresholds.
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Last edited by david entwistle on Sun Jan 04, 2009 1:31 am; edited 14 times in total |
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Davej
Joined: 10 Feb 2005
Posts: 3147
Location: Sheffield (53° 21' N 1° 12' W)
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| Posted: Sat Jan 03, 2009 9:12 am Post subject: |
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Hi,
Thanks for all the info David and Alastair.
Seems ages since I have had any decent viewing and it is cloudy now (09.06)... but I hope I am not tempting fate here, just been on the beeb interactive weather channel and they say it will be clear for most of the country this evening. Fingers crossed.
ATB
Dave
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Alastair McBeath
Joined: 23 Jul 2005
Posts: 572
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| Posted: Sat Jan 03, 2009 9:53 am Post subject: |
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I was clouded-out overnight on January 2-3 as well, here in Northumberland. The skies started breaking a little after 9 a.m. this morning...
At least the live radio meteor results let us "see" something of what the shower's been up to - thanks David!
Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please) |
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markt
Joined: 26 Jul 2007
Posts: 420
Location: Brockmoor, nr Dudley
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| Posted: Sat Jan 03, 2009 11:08 am Post subject: |
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I was out observing saturn from 2am till 4am on the morning of 3rd january. In that time when my eye wasn't on the end of my scope I saw 12 meteors (Quadrantids) - all 2nd/3rd magnitude with quite a short flight path - say 30(ish) degs long. The brightest was a 1st magnitude one, which traversed some 60 degrees of sky.
Given the fact I was observing saturn on and off for this 2 hour window I doubt this can be classed as a 'report' - but I thought i'd share it as an 'observation.'
My favorite meteor of the session was a zero to -1 mag sparodic,, bluish white in colour, that shot down from the zenith, through leo, before disappearing in the southern quadrant of the sky.
A jolly cold but thoroughly enjoyable early hours session! 
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Dave Mitsky
Joined: 22 Nov 2008
Posts: 81
Location: PA, USA, Planet Earth
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| Posted: Sat Jan 03, 2009 12:41 pm Post subject: |
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This morning I drove to the Astronomical Society of Harrisburg's Naylor Observatory and observed 30 Quadrantid meteors over a span of approximately two hours. I counted only nine during the first hour, which began shortly after 3:00 a.m. EST (7:00 UT). At 3:20 a.m., I saw my first meteor. Clouds covered the northern sky after the first hour so I spent some time in the Asper Building, warming up and having some hot cocoa. I was about to leave when the sky began to clear. I decided to stay and counted for another hour until morning twilight brought things to a halt.
Of the 30 definite sightings, nine were rather dim, third magnitude or so. Six of the meteors were bright, between first and zero magnitude, with one or two of them perhaps as bright as -1. There were another five possible meteors that I caught with peripheral vision, so my total may actually have been 35.
All of the Quadrantids that I saw were white and many of them were rather slow moving. There was a mixture of short and longer lasting meteors and none left a persistent train. Most of them emanated from the vicinity of the Big Dipper, particularly around the handle. The limiting magnitude at the observatory was a bit better than 5.0 and the temperature was 28 degrees Fahrenheit (-2 degrees Celsius).
Dave Mitsky
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DigitalSky
Joined: 04 Apr 2006
Posts: 398
Location: Selsey, UK
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macca
Joined: 27 Dec 2008
Posts: 36
Location: CORNWALL
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| Posted: Sat Jan 03, 2009 8:02 pm Post subject: |
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| been clear skies most of the day and now its cloudy down here in cornwall, doubt wheter i'll get outside tonight. but i'll keep an eye on it just incase it does clear. |
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@@
Joined: 05 Nov 2006
Posts: 156
Location: solihull
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| Posted: Sat Jan 03, 2009 11:41 pm Post subject: |
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oh dear me  i saw two very decent quads last night one at around 0030 and another around 0200 and having forgotten about the quads i never realised, ayhoo, the sky here tonight is crystal, but it bloody freezing 
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macca
Joined: 27 Dec 2008
Posts: 36
Location: CORNWALL
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| Posted: Sun Jan 04, 2009 12:26 am Post subject: |
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its stayed cloudy down here all night, just popped outside a few minutes ago and no change.  |
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markt
Joined: 26 Jul 2007
Posts: 420
Location: Brockmoor, nr Dudley
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| Posted: Sun Jan 04, 2009 12:49 am Post subject: Re: Quadrantids 2009 |
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| david entwistle wrote: | My own counts decreased as the radiant passed close to the zenith (an expected peculiarity of radio observation), but recovered later as the radiant moves to a position lower in the sky.
Jeff's data is from a single TV video carrier at Bend, Oregon located 193 degrees to his south. It is running 58.9 kW and is moderate base line distance of 655 km. |
Hey David, hope you don't mind my asking, but why do radio meteor counts decrease as the radiant passes toward the zenith? Also, can you elaborate on 'Jeff's data is from a single TV video carrier' - in a nut shell - what's this about and how does it work?
Cheers buddy, Mark
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david entwistle
Joined: 13 Aug 2006
Posts: 660
Location: Goosnargh, north of Preston, UK
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| Posted: Sun Jan 04, 2009 2:42 am Post subject: Re: Quadrantids 2009 |
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| markt wrote: | Hey David, hope you don't mind my asking, but why do radio meteor counts decrease as the radiant passes toward the zenith? Also, can you elaborate on 'Jeff's data is from a single TV video carrier' - in a nut shell - what's this about and how does it work?
Cheers buddy, Mark |
Hi Mark,
I don't mind at all, but I'll try not to go on too much.... 
I'll answer the second question first.
| Quote: | | 'Jeff's data is from a single TV video carrier' |
Jeff Brower is a Canadian radio meteor observer and he is using a radio receiver to listen to the reflections of a distant analogue television transmitter, as meteors enter the Earth's atmosphere.
The old analogue TV transmissions have separate sound and vision transmitters. The vision signal is amplitude modulated onto the radio frequency signal. Amplitude modulation is an inefficient modulation method, by today's standards, as only half the transmitters power is used to carry information, in this case the picture. The rest of the transmitter power appears as a constant unmodulated carrier signal. Radio meteor observers take advantage of this carrier to detect meteors.
| Quote: | | why do radio meteor counts decrease as the radiant passes toward the zenith? |
To understand why radio meteor counts decrease, as the radiant approaches the zenith, you need to realize that radio meteor observers are looking at reflections, of terrestrial transmissions, from the meteor trails. The meteor leaves a filled 'tube' of ionized gas, as it passes through the upper atmosphere and it is these trails that provide the reflecting surface. The trails are all aligned parallel to each other and point towards the meteor radiant.
Understanding the forward-scatter case (when the transmitter and receiver are not co-located) takes a bit of practice, but the back-scatter case (where the transmitter and receiver are at the same location) is easier, so we'll consider that. Imagine you have a powerful light (transmitter) and the trails are shiny tubes - like long straight chrome shower rails. You are looking for reflections from the tubes...
The reflecting trails are in the upper atmosphere lets say at 100km above ground. Normal reflection geometry applies - the angle of incidence equals the angle of reflection.
As the radiant first rises there will be very few meteors, but their paths will be at a low angle to the observer's horizon. Imagine where the reflection points will be... They'll be in the area directly overhead and off to either side along the line perpendicular to the meteor's paths.
Imagine now that the radiant has risen to 45 degrees above the horizon. There will be many more meteors entering the observer's sky, but where are the reflection points? They are now in the area of sky opposite the radiant and about 100km from the point directly above the observer. This is an optimum geometry for the back-scatter reflections - good meteor rates and relatively short path between the transmitter, the meteor and the receiver.
Imagine the radiant has risen to be directly overhead. The meteors are traveling vertically down through the observer's sky. Where are the reflection points? It's a tricky one. If you are imagining a flat Earth, then there are no reflection points. If you can imagine a curved earth, then you'll find that the reflection points do exist, but they are now in a ring around the observer's location and are all very distant.
It is the movement of the reflection points which results in the changing sensitivity of the system to meteors. Radio meteor observer give it the name observability function.
As I say, the forward-scatter [corrected 23/01/09] case is more complex, but the same ideas apply. The reflection points become distant and the reflections become weak as the radiant approaches the zenith.
If you'd like to know more, I'll be happy to tell you what I can. If you'd like to read up on the subject, then there are a number of good web sites, but the best source of information is probably the book, "Meteor Science and Engineering" by D. W R. McKinley. There will shortly be an SPA information sheet about the topic.
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Last edited by david entwistle on Fri Jan 23, 2009 6:11 pm; edited 1 time in total |
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Melanie
Joined: 28 Nov 2007
Posts: 153
Location: Hampshire, UK
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| Posted: Sun Jan 04, 2009 9:20 am Post subject: |
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Wow those are great Pete, brilliant, i didn't see any last night still got to get that bracket for scope you suggested.. bought a bracket for tripod yesterday for my binoculars, and it doesn't fit them! doh!
I would like to take pictures i've got a long way to go.... |
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markt
Joined: 26 Jul 2007
Posts: 420
Location: Brockmoor, nr Dudley
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| Posted: Sun Jan 04, 2009 10:59 am Post subject: |
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Thanks for your reply David!
I thought that was what was going on with both of my questions.
Regards, Mark
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