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(meteorobs) NAMN Notes: June 1999
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NAMN Notes: June 1999
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Introduction:
NAMN Notes is a monthly newsletter produced by the North American Meteor
Network, and is available both via email, and on the NAMN website at:
http://web.infoavedot net/~meteorobs
Contents:
1. The Major Shower for June...
2. June Lyrids - Deja Vu...
3. Other June Showers...
4. The Daylight Streams...
5. Meteor Shower Codes...
6. New Comet...
7. Upcoming Meetings...
8. For more info...
1. The Major Shower for June...
What is the main shower for the month of June? Well, the best way to find
out is to look on the website of the IMO, the International Meteor
Organization at www.imodot net, and check out the 1999 meteor shower calendar!
Looking down the 'Maximum Date' column on the 'Working List of Visual Meteor
Showers', you will find absolutely no dates in June where specific meteor
showers have a peak of activity! In fact, reading down the 'Activity
Period' column, there is only one shower on the list that actually has any
significant activity this month.
This is the Sagittarids (SAG), which stretch from about April 15th to July
15th, and just keep moving from constellation to constellation along the
ecliptic. And just how significant is this activity? Well, as far as
number of meteors seen per hour goes, the Zenithal Hourly Rate (ZHR) is only
about 5 meteors per hour, although this sometimes can be a bit higher. These
are medium velocity meteors, travelling at about 30 km per second.
This shower is part of the 'ecliptic activity' which is old comet debris
long since spread out along the path of the ecliptic. It is so spread out
and diffuse that we cannot even figure out what comets (or other bodies)
fragmented over time and formed this band of particles which the earth
encounters. It is not even a uniform band of particles. Sometimes we
encounter 'clumps' of material, and see higher rates. Also, if we plot the
meteors carefully, we can often find localized areas along the ecliptic - or
just above or below it - from which more meteors radiate.
The name given to the ecliptic 'shower of the month' varies, as this
activity is often given the name of the constellation from which the meteors
radiate. In May, we called them the alpha Scorpiids, as the radiant early
that month was near Antares, the bright reddish star of the Scorpion. In
June, the ecliptic shower is usually just called the Sagittarids.
The ecliptic radiant positions are as follows for this month:
May 30: 256 deg, ie. RA 17h 04m, Dec -23, lower Ophiuchus, up to right of
theta
June 10: 265 deg, ie. RA 17h 40m, Dec -23, lower Ophiuchus, up to left of
theta
June 15: 270 deg, ie. RA 18h 00m, Dec -23, near M20 in Sagittarius
June 20: 275 deg, ie. RA 18h 20m, Dec -23, up from teapot lid in Sagittarius
June 25: 280 deg, ie. RA 18h 40m, Dec -23, near M22 in Sagittarius
June 30: 284 deg, ie. RA 18h 56m, Dec -23, near nu Sagittarius
It is very useful to plot the meteors from this ecliptic activity, in order
to try to isolate some of the localized activity, the 'clumps' of debris as
it were, that the earth may encounter.
For assistance in judging magnitudes of any brighter meteors seen (and this
ecliptic activity can produce fireballs), the following are the magnitudes
of some of the brighter planets visible this month, taken from the Handbook
of the Royal Astronomical Society of Canada:
Start of month/11th/21st/end of month:
Venus in the evening sky: -4.2/ -4.3/ -4.4/ -4.4
Mercury in the evening sky: -1.6/ -0.6/ +0.1/ +0.7
Mars all night: -1.1/ -0.8/ -0.6/ -0.4
Jupiter in the morning sky: -2.1/ -2.2/ -2.2/ -2.3
Saturn in the morning sky: 0.1
2. June Lyrids - Deja Vu...
So, if there are no other showers listed for June on the IMO working list,
does that mean that no other meteors will be visible? No, there will always
be meteors, as there will always be debris of some sort that the earth will
encounter.
The challenge is to find out what and where it is! An example of this is
the June Lyrid shower, which the IMO does not put on its 'working list' but
which it encourages all observers to look for this year. Some activity was
seen by observers in the northern hemisphere back in the 1960's and 1970's,
and "evidence for its existence has been virtually zero since" according to
the IMO.
As an aside here, your female Canadian co-author was one of those observers
of June Lyrids in the 1970's, and some of the details are in the Mid-October
issue of Meteor News, No. 8, 1971. "The mean radiant from 37 meteors
plotted by the Ottawa group was 18h33m, +41 degrees (plots on Jun. 14/15,
15/16, and 16/17)." There is also a writeup on the Ottawa team in that
issue. There were other reports of June Lyrids in subsequent years of
Meteor News.
The IMO lists the date of possible maximum activity as June 16th, with
shower members visible from the 11th to the 21st. The radiant at maximum is
given as 278 degrees, ie. RA 18h 32m, Dec +35, which is a point forming an
equilateral triangle with alpha and beta Lyra. The meteors are average
velocity, at about 31 km per second. The IMO asks that all potential June
Lyrids be very carefully plotted, and states that "confirmation or denial of
activity from this source in 1999 would be very useful."
3. Other June Showers...
There are other weak minor showers visible in June, but unless you plot the
paths of your meteors, it is unlikely that you will be able to differentiate
them from any random meteors seen. This is why it is a good idea to learn
and practice plotting your meteors on the special plotting maps available.
It is also interesting at the end of the night to see what you have plotted!
This is how new meteor showers are found.
Some of these very weak showers (not on the IMO working list) are as
follows, from the notes of ALPO, the Meteor Section of the Association of
Lunar and Planetary Observers. These are provided to show that there is a
lot of very minor meteor activity present at any given time - but at such
low rates that only plotting over hours or days will detect it!
The omega Scorpiids reach a maximum on June 1st, with a radiant at RA 15h
56m, Dec -20, just above the bright star Dschubba in the top of the 'J' of
Scorpius. These are slow meteors, at about 21 km per second.
The gamma Sagittarids have a maximum on June 6th, with a radiant at RA 18h
04m, Dec -26, about 5 degrees above the spout of the teapot, and are just
barely average velocity, at about 29 km per second. Both of these showers
can be seen until about the middle of the month.
The theta Ophiuchids reach a maximum on June 13th, but can be seen basically
all month, according to ALPO. The radiant at maximum is at RA 16h 36m, Dec
-15, just above and to the left of phi Ophiuchus - and not near theta at
all. These are just barely average velocity meteors, at about 27 km per
second.
As an aside here, Kronk lists the maximum of the theta Ophiuchids as
centered on June 10th, with meteors visible until about the 16th - but a
radiant at 265 deg, ie. RA 17h 40m, Dec -28, about 5 degrees down and to the
left of theta Ophiuchus. How can this be - a different date, and a
different radiant, but the same name? Taking a look at the coordinates for
the ecliptic activity on this date, we see that on June 10 the radiant for
the Sagittarids is at 265 deg, ie. RA 17h 40m, Dec -23 - in lower Ophiuchus,
up to left of theta. Both the Sagittarids and Kronk's theta Ophiuchids have
the same longitude in the sky, but one is above the line of the ecliptic in
the sky, and one slightly below it. Ecliptic showers often have some
meteors radiating from above, and some from below, so it seems that it is
indeed the ecliptic activity, and not a separate shower. No wonder the
naming of showers along the ecliptic is confusing for observers!
In the last half of June, several other weak minor showers become active.
The tau Cetids, fast meteors at about 66 km per second, reach a maximum
level of activity on June 26th, at RA 01h 36m, Dec -12, about 5 degrees up
to the right of tau Cetus. The tau Aquarids, also fast, at 63 km per
second, have a maximum several days later, on June 28th, with a radiant at
RA 22h 48m, Dec -12, just above tau Aquarius.
As noted above, these are extremely minor showers - with very low rates -
but are a challenge to those of you interested in carefully plotting what
you see!
4. The Daylight Streams...
The Arietids are a daylight stream with a maximum on June 7th at 21h UT, and
a radiant at 44 deg, ie. RA 2h 56m, Dec +24, about halfway between the
Pleiades and the star Hamal in Aries. The zeta Perseids are also a daylight
stream, with a maximum on June 9th at 20h UT, and a radiant at 62 deg, ie.
RA 4h 8m, Dec +23, about 5 degrees to the left of the Pleiades.
In spite of being daylight streams, there have been some isolated reports of
nighttime visual sightings of these meteors - in the hours soon after sunset
and soon before sunrise. These are both strong showers, with rates of about
60 meteors per hour for the Arietids at maximum, and 40 per hour for the
zeta Perseids. If you see any unusual meteors coming up from the horizon,
plot them!
5. Meteor Shower Codes...
A recent discussion taking place on the meteor mailing list dealt with the
naming of meteor showers and the resultant abbreviations observers use for
the showers. So for your personal use, we bring you a sampler of meteor
showers and the three-letter code that you are most likely see being used.
This list is adapted from the IMO and lists showers an observer is most
likely to see activity from during the year.
Quadrantids (QUA) delta Cancrids (DCA)
delta Leonids (DLE) Virginids (VIR)
Lyrids (LYR) pi Puppids (PPU)
eta Aquarids (ETA) Sagittarids (SAG)
Pegasids (JPE) July Phoenicids (PHE)
Pisces Austrinids (PAU) Southern delta Aquarids (SDA)
Alpha Capricornids (CAP) Southern iota Aquarids (SIA)
Northern delta Aquarids (NDA) Perseids (PER)
Kappa Cygnids (KCG) Northern iota Aquarids (NIA)
Alpha Aurigids (AUR) delta Aurigids (DAU)
Piscids (SPI) Draconids (GIA)
Epsilon Geminids (EGE) Orionids (ORI)
Southern Taurids (STA) Northern Taurids (NTA)
Leonids (LEO) alpha Monocerotids (AMO)
Chi Orionids (XOR) Phoenicids (PHO)
Puppid-Velids (PUP) Monocerotids (MON)
Sigma Hydrids (HYD) Geminids (GEM)
Coma Berenicids (COM) Ursids (URS)
6. New Comet...
While you're out meteor observing, do you ever wonder what comets (and maybe
future meteor streams) are right out in front of you? There is actually a
fairly decent comet within amateur reach at the moment. Comet Lee, C/1999
H1, was discovered visually down in Australia by Steve Lee while he was
observing at a southern star party. It will brighten as it moves north and
then behind the sun, and will move into our morning northern sky in late
July.
Coordinates for June are as follows, from Don Machholz's 'Comet Comments'
newsletter, available both on his website, at:
http://members.aol.com/cometcom/index.html
and by email, by contacting him at: DonM353259@aol.com
C/1999 H1 (Lee)
Date(00UT) R.A. (2000) Dec Mag
06-01 08h34.1m +03d54' 7.5
06-06 08h29.2m +08d38' 7.4
06-11 08h24.8m +12d38' 7.3
06-16 08h20.8m +16d05' 7.1
06-21 08h16.6m +19d07' 7.0
06-26 08h12.3m +21d51' 6.9
07-01 08h07.5m +24d22' 6.7
(June 1 - head of Hydra, July 1 - upper Cancer)
7. Upcoming Meetings...
July 15-18, 1999:
Starfest, Canada's largest amateur astronomical convention, is being held
near Mount Forest, Ontario. This is an camping event, with observers
bringing tents and telescopes. There are a number of special talks this year
on meteors, meteorites and comets. Dr. Peter Brown will talk on 'Prospects
for a Leonid Meteor Storm in 1999'. Phil Gebhardt will give a talk on 'Radio
Observations of Meteors'. Dr. Richard Herd, Curator of National Collections
at the Geological Survey of Canada will give a presentation 'Meteorites',
and discuss Canadian meteorite research and recovery. Dr. Paul Chodas,
Research Scientist at NASA's Jet Propulsion Laboratory will give several
presentations: 'Calculating Orbits for Asteroids and Comets' and 'Predicting
Comet and Asteroid Impacts'. For more info, and full program details, visit
the website of the NYAA, North York Astronomical Association, at:
http://www.interlog.com/~nyaa
July 26-30, 1999:
The Asteroids, Comets, Meteors 1999 Conference is being held at Cornell
University, near Ithaca, in New York State. Details are available on their
website at: http://scorpio.tn.cornelldot edu/ACM. The abstracts for the talks
and poster sessions are now available online and make very interesting
reading! Although this is a professional conference, some North American
amateurs are hoping to attend. (NAMN members planning to attend, please
also advise Mark Davis, NAMN Coordinator, at MeteorObs@charlestondot net.)
August 7-15, 1999:
The 16th annual Mount Kobau Star Party, MKSP '99 will be held in southern
British Columbia, Canada, with talks and events on August 12, 13 & 14. Guest
speakers will include meteor researcher Dr. Martin Beech, a member of the
Canadian Leonid Team which sent an expedition to Mongolia last November. Dr.
Beech, will talk on Meteor Storms, Past, Present, and Future. Other speakers
include Gary Seronik from Sky & Telescope, Edmonton deep sky observer Larry
Wood, and astronomers from both the Dominion Radio Astrophysical Observatory
in Penticton and the Dominion Astrophysical Observatory in Victoria. For
more information, check out the website at http://www.bcinternet.com/~mksp
or contact the President of the Mount Kobau Astronomical Society, Jim
Failes, eij@bcinternet.com
September 23-26, 1999:
The 1999 International Meteor Conference (IMC), the annual conference of the
International Meteor Organization, is being held in Frasso Sabino, Italy.
The cost, including conference, lodging, and meals, is approximately $200
U.S. For more information, see the IMO website at http://www.imodot net
8. For more info...
Contact:
Mark Davis, MeteorObs@charlestondot net
Mt. Pleasant, South Carolina, USA
Coordinator, North American Meteor Network
And check out:
NAMN home page:
http://web.infoavedot net/~meteorobs
Back issues of NAMN Notes can be found on-line at the website.
To subscribe to the meteor email list or
To find out information on our weekly chat sessions:
Contact Lew Gramer at:
owner-meteorobs@jovian.com
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Here's to 'Clear Skies' for June!...
June 1999 NAMN Notes co-written
by Mark Davis and Cathy Hall
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