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(meteorobs) NAMN Notes: July 2001
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NAMN Notes: July 2001
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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. Southern Delta Aquarids...
2. Other Meteor Activity in July...
3. The Dog Days of Summer...
4. A Comet for the Comet Starved...
5. A Sampling of Boschat...
6. Upcoming Meetings...
7. For more info...
1. Southern Delta Aquarids...
The southern delta Aquarids (SDA) are the main shower for the month of
July, reaching a maximum on July 28th, with a radiant at 339 degrees, ie RA
22h 36m, Dec -16, which is about 5 degrees to the right of the star delta
Aquarius. This is the star known as Skat, often thought of as the right knee
of the
Water Bearer. The Zenithal Hourly Rate (ZHR) is about 20 meteors per
hour. This is the number of meteors that an observer would expect to see
with the unaided eye from a dark site in the country, if the radiant, the
area in the sky where the meteors seem to come from, is directly
overhead. These are average velocity meteors, at about 41 km per second.
The southern delta Aquarids can be seen from about July 12th to August
19th. At mid-month, on July 15th, just after activity starts, the radiant
will be at 329 degrees, ie RA 21h 55.8m, Dec -19, which is about 4 degrees
down to the left of the star delta Capricornus, the top left star of the
big triangle that is the Goat.
According to the International Meteor Organization (IMO), in their
'Handbook for Visual Meteor Observers', these meteors are believed to be
debris from Comet 96P/Machholz 1. In talking about the delta Aquarid
complex (both northern and southern streams), the IMO then states:
"Computer simulations of these meteor showers' evolution indicated a
possible relationship between the current delta Aquarids and the past
orbital elements of the Quadrantids... Still another remarkable
relationship with the delta Aquarids has been found. The Arietids, a
daylight shower in June, display their maximum activity on June 1... After
perihelion passage, this stream encounters the Earth's orbit again on July
28 with a predicted radiant... exactly coincident with the delta Aquarid
radiant!"
It is interesting to think about where these meteors come from when we are
out at night, observing under the stars. All these complicated
relationships between streams of old comet debris must keep the meteor
theorists awake at night too!
2. Other Meteor Activity in July...
July marks the start of the busy meteor season. There are quite a number
of showers visible to the unaided eye - and it starts to become a little
tricky to tell them all apart. We would recommend marking your meteor
radiants on star maps to help keep them all separate in your mind.
For easy reference, print yourself off a copy of our 4 NAMN star charts,
available at http://web.infoavedot net/~meteorobs/charts.html. These show the
constellations, RA and Dec sky coordinates, and the magnitudes of stars
useful to use as standards for judging the brightness of the meteors you
see. For detailed information on how to record meteors in a format useful
for researchers, check out our NAMN Observing Guide at
http://web.infoavedot net/~meteorobs/guide.html. If you have any questions,
drop a note to our NAMN Coordinator at MeteorObs@charlestondot net.
The June Bootids (JBO), although having reached a maximum on June 27th, can
be seen until about July 2nd. These are very slow meteors, with a velocity
of about 18 km/sec, so are very distinctive. They are debris from Comet
Pons-Winnecke. The radiant on July 1st is at 225.4 degrees, ie RA 15h
1.8m, Dec +46.8, which is about 6 degrees north of the star beta Bootes,
the top star of the Herdsman, the star called Nekkar. ZHR rates will be
extremely low.
The Sagittarids (SAG) continue to represent the ecliptic activity, the
meteor activity whose radiant moves along the path of the ecliptic in the
sky. These meteors are fairly slow too, with a velocity of about 30 km per
second. The ZHR rate is about 5 meteors per hour. On July 5th, the
radiant will be at 289 degrees, ie RA 19h 16.2m, Dec -22, about 2 degrees
down to the left of the star pi Sagittarius, and the meteors will last
until about July 15th, when the radiant will have moved to 298 degrees, ie
RA 19h 52.2m, Dec -21, the position of which forms a large triangle with
the right side of Capricornus.
The Pegasids (JPE) reach a maximum on July 9th, with a radiant at 340
degrees, ie. RA 22h 40.2m, Dec +15, which is about 4 degrees north of the
star zeta Pegasus. These are fast meteors, at about 70 km per second, and
can be seen from about July 7th to 13th. At maximum on the 9th, ZHR rates
will be about 3 meteors per hour.
The July Phoenicids (PHE) reach a maximum on July 13th, with a radiant at
032 degrees, ie RA 2h 7.8m, Dec -48, which is about 27 degrees due south of
the star upsilon Cetus, the left foot of Cetus, way far south for observers
in northern latitudes, and better observed by those in southern
locations. These are average velocity meteors, at about 47 km per second,
and rates are variable. They can be seen from about July 10th until the
16th.
The northern delta Aquarids (NDA) start about July 15th, but won't reach a
maximum until August 8th. On July 15th, the radiant will be at 316
degrees, ie RA 21h 4.2m, Dec -10, which is about 7 degrees north of the
star theta Capricornus, above the crook in the top of Capricornus. By July
30th the radiant will have moved to 327 degrees, ie RA 21h 48m, Dec -8,
which is about 4 degrees down to the left of the star beta Aquarius, the
star Sadalsuud. Rates in July will be very low, as even at maximum in
August, the ZHR rate will only reach about 4 meteors per hour. These are
average speed meteors, at about 42 km per second.
Perseids - yes, we said Perseids! - start to become visible about July the
17th, although won't reach a peak until August 12th. Rates in July will be
small, but quite noticeable. Perseids (PER) are fast meteors, at about 59
km per second. The radiant on July 20th will be at 018 degrees, ie RA 1h
12m, Dec +52, which is about 3 degrees south of the star theta
Cassiopeia. By July 30th the radiant will have moved to 029 degrees, ie RA
1h 55.8m, Dec +55, which is about 9 degrees south of the star epsilon
Cassiopeia, the top left star of the "W".
The southern iota Aquarids (SIA) start in late July, about the 25th, but
don't reach a maximum until August the 4th. On July 25th, the radiant will
be at 322 degrees, ie RA 21h 28.2m, Dec -17, which is about a degree to the
left of the star iota Capricornus. Rates will be very low. Even at
maximum in August, the ZHR rate will only reach about 2 meteors per
hour. These are average velocity meteors, at about 34 km per second.
The Pisces Austrinids (PAU) reach a maximum in late July, on the 28th, but
can be seen from about July 15th until about August 10th. At maximum, the
radiant will be at 341 degrees, ie RA 22h 43.8m, Dec -30, which is about 3
degrees to the right of alpha Pisces Austrinus, the star called
Fomalhaut. These are average velocity meteors, at about 35 km per
second. ZHR rates will be about 5 meteors per hour at maximum.
Lastly, the alpha Capricornids (CAP) reach a maximum on July 30th. The
radiant early in the month, on July 5th, is at 285 degrees, ie RA 19h 00m,
-16, which is about 10 degrees north of the star sigma Sagittarius, the top
handle star of the "Teapot". By maximum on July 30th, the radiant will
have moved to 308 degrees, ie RA 20h 31.8m, Dec -10, which is about 4
degrees up to the left of the star alpha Capricornus, the top right star of
the triangle of Capricornus. ZHR rates at maximum will be about 4 meteors
per hour, and the meteors will be nice and slow, with a velocity of about
25 km per second. The alpha Capricornids can be seen from about July 3rd
until about August 15th. Although few and far between, these are wonderful
meteors to see!
Besides recognized showers, there is also sporadic meteor activity,
meteors that are random, or belong to long-ago, now untraceable
showers. These occur at a rate of about 7 per hour, visible to the unaided
eye.
Full moon this month is on July 5th, last quarter on July 13th, new moon on
July 20th, and first quarter on July 27th. Mars is up all month in
Ophiuchus, at about magnitude -2.0 for most of the month. Venus is the
very bright pre-dawn object low in the east, at magnitude -4.1 for most of
July. Saturn rises about 3 hours before the sun, at magnitude -0.3, and
will be close to Venus on the 15th.
For those following the planets, on Tuesday July 17th, at 18h UT, Venus
will be occulted by the moon. This will be visible from parts of the
United States and southern Canada, and also from Hawaii and the
Caribbean. Those not on the occultation path will see a close
approach. Also on the same date, at 13h UT, Saturn will be occulted by the
moon, visible from South America except the northwest and extreme
south. Two days later, on Thursday July 19th, at 0h UT, Jupiter will be
occulted, visible from Indonesia and the Pacific Ocean, and at 13h UT,
Mercury will be occulted, visible from northern Europe, northern Russia,
the Arctic, Alaska, and western Canada.
3. The Dog Days of Summer...
Interesting expression, that. For this Canadian co-author, it is finally
warming up in the 'Great White North'. That's a term coined on a Canadian
television show featuring the Mackenzie Brothers, and refers to the common
misconception that Canada has snow and igloos year-round. This is, of
course, very close to the truth, with snow never being more than 6 months
away. We can get snow in late April, and we expect it anytime after
mid-October. However, when it gets hot, it gets hot and humid and buggy.
For meteor observing, we always keep our gear packed in our cars up here -
the insect repellent, the down parka - the cloth to mop our brow, and the
hand warmers to keep our fingers from freezing. It is a country of
extremes.
So, what is recommended gear for summer meteor observers? For starters, a
reclining lawn chair is a good idea, something that enables you to lean
back, and center your gaze about halfway between your horizon and your
'zenith' overhead. It may get cool - or feel cool later in the night
relative to the daytime temperatures, so a light blanket is a good
idea. For underneath you, a foam mat of some sort will help your back and
butt from getting too tired in one position for a period of time.
Do you have bugs? We invented mosquitoes here. This observer highly
recommends a cool shower before observing - and don't put on deodorant or
cologne, or anything scented. Just have your shower, and put on insect
repellant. Put it on all over your face, and neck, and on the top of your
head, and behind your ears, and all over your wrists and hands. You may
wish to spare the palms of your hands, as some insect repellants will
damage the finish on plastics, such as tape recorders and stuff. If you
object to insect repellant, try out the Avon 'Skin So Soft' product line -
body lotion, oil, hand lotion or whatever. Bugs are repelled by it, and
people are not!
Dress in something that is cool, but that will cover you wherever your
insect repellant does not. Make sure the mosquitoes can't crawl up your
pant legs. If it is very humid, you may want to take some sort of
waterproof tarp out with you, to keep the dampness off in the wee hours of
the morning.
Take your recording sheets, and a clipboard and pencils. Recording sheets
can be printed off from the NAMN website. Take a flashlight covered with
red plastic so you won't destroy your dark adaptation. Take a second
flashlight for when you lose your first one. Set your watch ahead of time
to make sure it is accurate, and make sure you note what type of time you
are using - local, like Eastern Daylight Time, or set to Greenwich,
England, in other words, Universal Time.
Take your star charts, like the NAMN charts we talked about in the meteor
shower info above, to use as a refresher for your constellations, to mark
your shower radiants on, and to use for judging meteor magnitudes. Take
some of the IMO charts showing the 'limiting magnitude' triangles, so you
can judge how good your sky is. Both of these items are on the NAMN
website, or linked to it. Check them out.
You may wish to take a drink in a thermos, and a snack. You may or may not
wish to eat the snack while observing, depending on what the local wildlife
situation is like. I would rather pass on a jelly donut than have some
raccoon stick his head over my shoulder and want a bite! If you have
animals in your area, you may wish to pick yourself up an 'animal warning'
light, a motion sensitive battery operated security light, that you can put
behind you while observing. It may scare you more than the animal, but it
does offer some peace of mind. Leave your car door unlocked.
Get yourself some sort of observing bag, and put all your loose stuff in
it. Keep this observing bag beside you while observing. If you have a
small pair of binoculars, you might want to put those in too, for looking
at interesting 'trains' left by meteors, or at the International Space
Station when it goes over, or for looking at the summer Milky Way during a
break in your meteor observing. This is the bag where you keep your spares
- your spare pencils, your spare flashlight, your insect repellent, your
Kleenex for wiping spare mosquitoes out of your eyes.
A little pocket radio is also a good idea. If you are observing by
yourself, it helps keep you alert. Yes, the Art Bell show and his late
night talk of aliens does broadcast to eastern Canada. A radio may help
keep animals away as well, if they hear human noises. If it doesn't, well,
then you won't worry as you won't hear them coming. Did I say the 'dog
days of summer'? Hopefully you will see more meteors than wildlife, and
have an enjoyable observing session!
If you have any questions on summer observing or meteor showers visible
this time of year, drop a note to our NAMN Coordinator. Share some of your
observing experiences with us!
4. A Comet for the Comet Starved...
The brightening of Comet LINEAR, C/2001 A2, has been in recent news - a new
naked eye comet! LINEAR stands for the Lincoln Near Earth Asteroid
Research project, and, as noted on the website at
http://www.ll.mitdot edu/LINEAR/, this project is funded by the U.S. Air
Force, with its goal being to "demonstrate the application of technology
originally developed for the surveillance of earth orbiting satellites, to
the problem of detecting and cataloging Near Earth Asteroids that threaten
the Earth."
The comet was found using the LINEAR GTS-2 telescope, a 1 meter folded
prime focus Cassegrain, located on the White Sands Missile Range in
Socorro, New Mexico. According to the website, LINEAR has confirmed 59,389
asteroids, of which 399 are classed as NEO's, Near Earth Objects - and
these figures are only as of May 20, 2000.
So, what about this latest comet? It was discovered on images taken
January 15th, 2001, at magnitude 15.8. It has since undergone a number of
outbursts in brightness, and multiple splitting of the nucleus. In early
July, this comet can be spotted with the unaided eye, in the pre-dawn
morning hours. A general chart can be found at http://www.spaceweather.com
and a more detailed finder chart at:
http://encke.jpl.nasadot gov/images/01A2/LINEAR-A2-2.gif.
It is coming up from Cetus in the southern sky, and moving through the head
of Pisces from July 6th to 8th. It will then head up towards the star xi
Pegasus, being just left of it on July 11th, very close to it on July 12th,
and to the right of it on July 13th. It will then head off to the right of
the Great Square of Pegasus, where it will be about 8 degrees north of the
star epsilon Pegasus, known as Enif, on July 19th. It will then head over
towards the Milky Way, and by July 31st, will be about 5 degrees north of
the nose of Delphinus - right about where Comet Hyakutake was on March 20,
1996!
Coordinates for Comet LINEAR, C/2001 A2 are as follows, adapted from the
Sky and Telescope website at http://www.skypub.com. If you need some basic
star charts to figure out where these coordinates are, print yourself off a
set of 4 from our NAMN website
at: http://web.infoavedot net/~meteorobs/charts.html
July 1 0h 40.4m -04 55
July 3 0h 17.3m -01 21
July 5 23h 54.9m +02 05
July 7 23h 33.5m +05 18
July 9 23h 13.2m +08 13
July 11 22h 54.2m +10 47
July 13 22h 36.6m +12 59
July 15 22h 20.4m +14 51
July 17 22h 05.6m +16 24
July 19 21h 52.0m +17 40
July 21 21h 39.8m +18 42
July 23 21h 28.6m +19 30
July 25 21h 18.5m +20 08
July 27 21h 09.4m +20 36
July 29 21h 01.2m +20 57
July 31 20h 53.8m +21 11
The comet will gradually fade during July, from visible with the unaided
eye at about magnitude 4, down to visible in binoculars and small amateur
telescopes. Recent observations can be found
at: http://encke.jpl.nasadot gov/RecentObs.html#01A2
Details on the history of this comet, and some photos, can be found on Gary
Kronk's 'Comets and Meteor Showers' website at:
http://cometography.com/lcomets/2001a2.html
Get out and take a look at this comet in the morning sky! Naked eye comets
do not come around too often. If you have binoculars or a telescope, check
out LINEAR with those as well. Try some photos with your camera and
tripod. With a normal 55mm lens and fast film, you can take about a 30
second photo before noticeable 'trailing' occurs with 35mm film. Dawn will
also be fast approaching though, so 'bracket' your exposures - take a
variety of timed shots, some long, some shorter.
Comets are very often the source of the meteor showers that we observe - so
don't pass up this opportunity to see Comet LINEAR, coming now to a sky
near you!
5. A Sampling of Boschat...
NAMN member Mike Boschat has a unique website - an alphabetical A to Z
listing of hundreds and hundreds of astronomical webpages. This is
probably the best astronomical link list available for the amateur
astronomer! Mike's amazing astro list is
at: http://www.mscs.daldot ca/~andromed/
It will take you a while to explore it. For your July web cruising, here
is a sampling:
Space Weather Now
by NOAA, the National Oceanic and Atmospheric Administration
http://sec.noaadot gov/SWN
Spacewatch
http://www.space.com/spacewatch/
Your Sky
by John Walker
http://www.fourmilab.ch/yoursky
Heavens Above
maintained by Chris Peat
http://www.heavens-above.com
Weekly Information about Bright Comets
http://www.aerithdot net/comet/weekly/current.html
& Comet Rendezvous Calendar
http://www.aerithdot net/comet/rendezvous/current.html
both by Seiichi Yoshida
Build a Barn Door Tracker
Astronomy Boy - Resources & Tutorials for Amateur Astronomers
by Jeff DeTray
http://www.astronomyboy.com/
The Nine Planets - A Multimedia Tour of the Solar System
by Bill Arnett
http://seds.lpl.arizonadot edu/billa/tnp
Terrestrial Impact Structures
by the Regional Geophysics Section of Natural Resources Canada
http://gdcinfo.agg.emrdot ca/toc.html?/crater
And some other link lists of interest listed on Boschat's site:
Astroweb Yellow Pages
by the Kalamazoo Astronomical Society
http://www.stargazingdot net/kas/astroweb.html
Astronomiae Historia/History of Astronomy
by Dr. Wolfgang R. Dick
http://www.astro.uni-bonndot de/~pbrosche/astoria.html
Mark Maimone's Homepage
with a link to the Computer Vision Homepage under his 'personal e-library'
http://www.cs.cmudot edu/afs/cs/usr/mwm/www/home.html
Links to Astronomy for Drennon's Students of Astronomy
by Bill Drennon
http://www.cvc.org/astronomy/
& the Drennon Dolphin Websurfer
http://ns.theworks.com/users/bdrennon
6. Upcoming Meetings...
August 6-10, 2001 - Sweden:
The Meteoroids 2001 conference will be held at the Swedish Institute of
Space Physics in Kiruna, Sweden. Topics covered will include historical
observations and perspectives on meteoroids; dynamics, sources and
spatial distribution; detection and characteristics of meteoroids from
interstellar space; the meteoroid interaction process in the atmosphere;
hypervelocity impact effects on spacecraft; Leonid meteor storms;
optical observations of meteors; and meteor radar work. For
information, contact Asta Pellinen-Wannberg at
asta.pellinen-wannberg@irf.se and check out the website at
http://www.irf.se/Meteoroids2001.
September 20-23, 2001 - Slovenia:
IMC 2001, the worldwide meeting for meteor observers of the
International Meteor Organization, will be held this year in the town of
Cerkno, in Slovenia. This is a convention for both amateurs and
professionals. For North Americans not familiar with the map, Slovenia
is on the Adriatic Sea, east of Venice and south of Austria. It is
within driving distance of major European cities. This is a great
opportunity to meet and chat with observers from all over the globe -
and a wonderful excuse to visit Europe as well! Come join us! Details can
be found on the IMO website at http://www.imodot net.
7. For more info...
Contact:
Mark Davis, MeteorObs@charlestondot net
Goose Creek, 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 NAMN website, and
in the meteorobs archives at:
http://www.tiacdot net/users/lewkaren/meteorobs
by selecting 'Browse Archive by Month'
To subscribe to the meteor email list or
To find out information on our weekly chat sessions:
Contact Lew Gramer at:
dedalus@alum.mitdot edu
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Here's to 'Clear Skies' for July...
July 2001 NAMN Notes co-written
by Mark Davis and Cathy Hall
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