NAMN Notes: July 2002 - northern delta Aquarids, upcoming co

by by Mark Davis and Cathy Hall

More articles in NAMN

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://www.namnmeteors.org


Contents:
1. Lots of Aquarids in July...
2. All the Other Showers to Watch for...
3. Summer Reading for Meteor Enthusiasts...
4. Upcoming Meetings...
5. For more info...
1. Lots of Aquarids in July...

Summer is a busy season for meteor observers, and in July, the meteors really start to fly!

If you are already familiar with the summertime night sky, you are starting well-prepared. If you are just starting out in meteor observing, print off a set of NAMN star charts from http://www.namnmeteors.org/charts.html These charts will help teach you the constellations, give you some standard stars to judge the brightness of the meteors you see, and also give you some maps to mark your meteor radiants on. What are radiants? Every meteor shower has an area in the sky where their meteors seem to come from - this area is called the radiant.

The best shower for the month of July is the southern delta Aquarids (SDA), reaching maximum activity 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. RA and Dec are coordinates in the sky - look at the edges of our NAMN star maps and you will see them marked. RA stands for Right Ascension, and is like longitude in the sky. Dec stands for Declination, and can be compared to latitude.

The ZHR (Zenithal Hourly Rate), for this shower is about 20 meteors per hour. This is the number of meteors that an observer would see, on average, every hour if they were out under a dark country sky (no lights, no moon), and if the radiant, the area in the sky where the meteors seem to come from, is directly overhead. Thus - to see more meteors, wait until the radiant is high in your sky, and get away from city lights!

These are average velocity meteors, at about 41 km per second. Meteors come in all velocities. Once you've been out observing for a while, you will be able to tell the difference between slow, medium and fast meteors.

The southern delta Aquarids can be seen from about July 12th to August 19th - and their radiant moves over this time period. For a map showing this movement, check out the website of the International Meteor Organization (IMO) at http://www.imo.net/calendar/cal02.html#Aquarids


2. All the Other Showers to Watch for...

If you haven't already printed off a set of our four NAMN star charts, now would be a good time. Set your printer to landscape mode, and go to http://www.namnmeteors.org/charts.html

The summer sky is full of meteor showers. In fact, it is hard to keep track of them all. Mark the various radiants on your maps and it will help you a lot!

If you want to try helping out the meteor researchers by recording data on the meteors you see, check out our NAMN Observing Guide at http://www.namnmeteors.org/guide.html

The June Bootids (JBO), although reaching a maximum on June 27th, can be seen until about July 2nd. These are slow meteors, at about 18 km per second, so would be quite distinctive. They are debris from Comet 7P/Pons-Winnecke. The number of meteors that can be seen is variable - back in 1998, ZHR rates hit from 50 to over 100 meteors per hour for over half a day. Monitor this shower very carefully in late June and early July! For a map showing the location of the radiant, go to http://www.imo.net/calendar/cal01.html#June-Bootids

The Sagittarids (SAG) last until about mid-July. These meteors are believed to be debris from a number of unknown bodies. Sagittarids are almost slow, with a velocity of about 30 km per second. ZHR rates are about 5 meteors per hour. Fireballs have been associated with this shower - so stay alert! The radiant of the Sagittarids follows along the path of the ecliptic in the sky. On July 10th, at new moon, the radiant will be at 293 degrees, ie. RA 19h 31.8m, Dec -22, which is about 5 degrees to the left of the star pi Sagittarius on a star atlas.

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. At maximum, ZHR rates will be about 3 meteors per hour. These are fast meteors, at about 70 km per second, and can be seen from about July 7th to 13th.

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. This shower is better observed by those in southern latitudes. Rates are variable. These are average velocity meteors, at about 47 km per second, and can be seen from about July 10th to 16th. Observations are encouraged by southern observers - in their 2002 Meteor Shower Calendar, the IMO states that "more data would be very welcome!"

The Pisces Austrinids (PAU) reach a maximum on July 27th, but can be seen from about July 15th to August 10th. ZHR rates will reach about 5 meteors per hour at maximum. These are average velocity meteors, at about 35 km per second. On July 27th, 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 known as Fomalhaut.

The alpha Capricornids (CAP) reach a maximum on July 29th. These are wonderful, slow meteors, with a velocity of about 25 km per second, and are spectacular to see. ZHR rates at maximum will be about 4 meteors per hour. They can be seen from about July 3rd to August 15th. Early in the month, on July 5th, the radiant will be at 285 degrees, ie. RA 19h 00m, Dec -16, which is about halfway between lambda Aquila and sigma Sagittarius, the star called Nunki. At maximum on the 29th, the radiant will have moved to 307 degrees, ie. RA 20h 28.2m, 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.

The southern iota Aquarids (SIA) start about July 25th, but won't reach maximum activity until August 4th. ZHR rates will be low in July, reaching about 2 per hour by maximum. These are average velocity meteors, at about 34 km per second. On July 25th, the radiant will be at 322 degrees, ie. RA 21h 28.2m, Dec -17, which is very near the star iota Capricornus. For a map showing all the various Aquarid radiants - and their movement in the sky over the next month - check out http://www.imo.net/calendar/cal02.html#Aquarids

The northern delta Aquarids (NDA) start about July 15th, but won't reach maximum activity until August 8th. ZHR rates in July will be very low, and even in August will only reach about 4 meteors per hour. These are average velocity meteors at about 42 km per second. The radiant on July 15th will be at 316 degrees, ie. RA 21h 4.2m, Dec -10, which is about 7 degrees due north of the star theta Capricornus. By July 30th, the radiant will have moved to 327 degrees, ie. RA 21h 48m, Dec -8, which is about 8 degrees north of delta Capricornus. Using the coordinates, you can plot this on your NAMN star charts - and should, as there are getting to be a lot of radiants to keep track of!

Perseids (PER) start to become visible about July 17th, although won't reach a maximum until August 12th. ZHR rates in July will be low, but noticeable. These 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, and by July 30th will have moved to 029 degrees, ie. RA 1h 55.8m, Dec +55. In constellation terms, on July 20th the radiant is about 3 degrees south of the star theta Cassiopeia and by July 30th will have moved to about 4 degrees up to the left of the star phi Perseus. A map showing the movement of the Perseid radiant during July and August can be found at http://www.imo.net/calendar/cal02.html#Perseids

Besides recognized main showers, and other minor showers, there is also sporadic meteor activity in July. This sporadic activity is about 7 meteors per hour visible to the unaided eye. This activity is comprised partly of random meteors and partly of meteors that belong to long-ago, now untraceable showers.

If you want to do some more reading on minor showers that are not on the 'Working List of Visual Meteor Showers' of the IMO, then check out Gary Kronk's 'Comets and Meteor Showers' website at http://comets.amsmeteors.org Most minor showers are really only detected by plotting your meteors on star charts, and doing an analysis after your observing session is over. Special maps are available for plotting with a gnomonic projection which allows you to plot your meteors as straight lines. The plotting maps generally in use are from the Atlas Brno, and are available free of charge from Mr. Robert Lunsford, IMO Secretary-General, at 161 Vance Street, Chula Vista, California 91910, USA.


In July, the moon phases are as follows:
Tues. July 02 last quarter
Wed. July 10 new moon
skinglow

Wed. July 17 first quarter
Wed. July 24 full moon
The magnitudes of the planets in July (at midmonth unless stated) are:
Mercury -0.3 low in east before sunrise, in first week of July
Venus -4.1 low in west after sunset
Saturn 0.1 low in east before sunrise, in late July
3. Summer Reading for Meteor Enthusiasts...

Summer is a great time for sunshine, cottages, and time at the beach! And, even if you're not into sun, sand and daylight... it is a great time to get some good reading in!

There are some good books out there right now, and some are just ideal for meteor fans. This Canadian co-author recently spent a half day relaxing at the local garage, waiting for truck repairs... and reading a novel by one of the astronomers at the Armagh Observatory! It's called "Nemesis", and is written by Dr. Bill Napier, an authority on impact hazards. It's about an asteroid that has been deflected onto a collision course with the United States, and how everybody deals with it. I haven't finished the book yet... my truck (only) needed front end work... but I would highly recommend the novel. Being written by a professional astronomer, it has lots of wonderful astronomical information throughout. The author also includes many witty comments on a variety of life's circumstances, which really make you smile...

On a non-fiction note, a good recent book is "Meteorites - Their Impact on Science and History", originally published in French as "Les Meteorites". It's a collection of very interesting articles by various authors on impacts, meteorites, and meteoroid origins. It is edited by Brigitte Zanda and Monica Rotaru, and put out by Cambridge University Press. There are lots of photos, and excellent charts and diagrams to explain concepts. The book is easily readable by amateur astronomers.

So... if you are being dragged off to a cottage, and are wondering what book to take along... grab one of these at your local bookstore. Both will entertain you!


4. Upcoming Meetings...

July 21-26, 2002, Los Angeles, California USA... The 65th annual meeting of the Meteoritical Society will be held at the University of California in Los Angeles. Special sessions planned include 'Mars: Meteorites and Missions' and 'Chondrule and CAI origins'. For information, check out www.lpi.usra.edu/meetings/metsoc2002

July 29-August 2, 2002, Berlin, Germany... The Asteroids, Comets, Meteors 2002 Conference will be held in Berlin, Germany. Topics that will be covered include comets, asteroids, meteor showers, interplanetary material, collisions and impacts, NEO's (near earth objects), the asteroid-meteorite connection, transitional objects, origin of comets, and many other related topics. This is the 8th ACM conference in a series, with a conference being held only every 3 years. It is being jointly organized by the DLR Institute of Space Sensor Technology and Planetary Exploration, the Max Planck Institute for Aeronomy, and the Technical University of Berlin. For details, contact J. Benkhoff at acm2002@dlr.de and check out the ACM 2002 website at http://berlinadmin.dlr.de/SGF/acm2002

September 3-6, Washington, DC, USA... The Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids, sponsored by NASA, will be held in Washington, DC. The workshop will review current knowledge of the physics and chemistry of the interiors of small cometary nuclei and asteroids, and will work towards several goals: determination of requirements for collision avoidance and impact mitigation technologies, determination of mission models and instrumentation needed, and construction of a roadmap for achieving the knowledge on which to base future systems to deal with possible impacts. Registration is $250 on or before July 1, and $350 after July 1. A list of the confirmed invited speakers can be found at http://www.noao.edu/meetings/mitigation/invited.html. For information, contact Nalin Samarasinha at nalin@noao.edu and check out the conference website at http://www.noao.edu/meetings/mitigation.

September 26-29, 2002, Frombork, Poland... IMC 2002, the International Meteor Conference, will be held in Frombork, Poland. This is the annual conference of the International Meteor Organization and welcomes all meteor observers, both amateur and professional. For information, check out http://www.imo.net and http://www.astrouw.edu.pl/~olech/pkim/imc2002/imc.html. For specific questions, contact Mariusz Wisniewski.

For more information on upcoming astronomy meetings, see: "International Astronomy Meetings List" http://cadcwww.hia.nrc.ca/meetings


5. For more info...
NAMN website: http://www.namnmeteors.org
Mark Davis,
meteors@comcast.net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network
Cathy Hall,
chall@cyberus.ca
Metcalfe, Ontario, Canada
Co-author, NAMN Notes
Lew Gramer,
dedalus@alum.mit.edu
Medford, Massachusetts, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'
Kevin Kilkenny,
4Meteors@aol.com
Staten Island, New York, USA
Coordinator, Fireballs and Meteorites

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