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
1. Time Passages and Meteor Friends...
2. Aquarids for the Summertime...
3. Other July Meteor Activity...
4. Upcoming Meetings...
5. For more info...
In these past weeks our meteor community has heard about several more observers who have 'slipped the bonds of earth' and passed away.
We would like to extend our condolences to their families - and to all those in our meteor community who have lost loved ones. We usually keep our conversations on topic and about meteors - and there may be others who have recently passed away that we have not heard about.
Our sympathies go out to veteran Florida meteor observer Norman McLeod, on the passing of his wife and observing partner, Joan.
Our sympathies also go out to the family of Stan Mott, a Canadian observer who was a member of Dr. Peter Millman's Springhill meteor team.
Many of us met Joan at the NAMN gathering in West Virginia back in 1998. She was a delightful and intelligent lady, and observed with Norman for many years.
Stan Mott was with Dr. Millman for the 1946 Giacobinid expedition - and we wrote up his meteor experiences in our NAMN Notes back in 1998. Our amateur meteor group in Ottawa knew Stan well. He was always there to encourage our meteor pursuits.
Astronomy has been a comfort, and an inspiration, for so many of us. We look to the skies to learn, and we look to the skies for comfort in times of need. We hope that the skies provide that comfort for these families...
The French astronomer Camille Flammarion expressed that sentiment in his writings of 1903:
"It is indeed difficult to resist a sense of profound emotion before the abysses of infinite space, at the sight of the innumerable multitude of worlds above our heads. We feel in this solitary contemplation of the heavens that there is more in the universe than tangible and visible matter: that there are forces, laws, destinies. Our... brains may know themselves microscopic, and yet recognize that there is something greater than the earth, the heavens; - more absolute than the visible, the invisible; - nobler than the common business of life, the conviction of beauty, of truth, and of good. We feel that an immense mystery broods over nature - over all human beings, over created things..."
"O night, mysterious, sublime, and infinite! withdrawing from our eyes the veil spread above us by the light of day, giving back transparency to the heavens, showing us the prodigious reality, the shining casket of the celestial diamonds, the innumerable stars that are set in the immeasurable distances of space! Without you we should know nothing..."
"O sacred night! If on the one hand you rest upon the heights of truth beyond the day's illusions, on the other your invisible urns pour down a silent and tranquil peace, a penetrating calm, upon our souls that weary of life's troubling; you make us forget struggles, deceptions, intrigues, the miseries of the hours of toil... Your domain is that of rest and dreams..."
Summer is upon us again. It's hard to believe that we're already halfway through the year. For those of us in northern climes, we could have snow in just over 3 months time. That sounds like excellent motivation for tolerating warm nights and hungry mosquitoes in our quest for meteors...
Aquarius? If you aren't already familiar with the constellation, get used to it now. We have a lot of summer meteors coming from Aquarius. It's often a hard constellation to make out if you are under light-polluted skies, but its pattern in the sky emerges as you travel to a darker site.
What's the pattern? Take a look at the star map by the SEDS group at http://messier.obspm.fr/map/Aqr.html. If you'd like to see a map of Aquarius, with Aquarius himself against the stars, check out Jan Wisniewski's website at http://www.astrosurf.com/jwisn/aquarius.htm. The mythical outline is based on Johannes Hevelius' Uranographia (1690). For the legends behind the constellation of Aquarius, check out the New Jersey website at http://www.ufrsd.net/staffwww/stefanl/myths/aquarius.htm
The southern delta Aquarids (SDA) reach 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. They can be seen from about July 12th to August 19th. For a map showing the radiant and its motion from night to night, check out the website of the International Meteor Organization (IMO) at http://www.imo.net/calendar/2007
The SDA's are average velocity meteors at about 41 km/sec. At the peak on July 28th, ZHR rates are about 20 meteors per hour.
What is ZHR? This is Zenithal Hourly Rate and is the number of meteors on average that an observer would expect to see in an hour if the radiant, the area in the sky where the meteors seem to come from, is directly overhead - and if an observer is out under dark country skies. If the radiant is not overhead, you will see less. If your sky is not really dark, you will see less. So - to see as many meteors as possible, get away from city lights and try to observe when the radiant is higher in the sky.
This shower is rich in faint meteors, but also has brighter meteors as well. The IMO also mentions that "radio work can be used to pick up the SDA... and indeed the shower can sometimes give a surprisingly strong radio signature." For info on what's involved in observing meteors by radio, more information can be found on their website at http://www.imo.net
We have a change in Aquarid meteors for this year though. NAMN follows the "Working List of Visual Meteor Showers" put out by the International Meteor Organization. In previous years, the IMO listed north and south delta Aquarids (NDA and SDA), and north and south iota Aquarids (NIA and SIA). No longer. Now we have just the SDA meteors. The IMO provides more info in their 2007 Meteor Shower Calendar:
"Fresh investigations of the near-ecliptic Aquarid and alpha-Capricornid (CAP) streams using IMO and other visual and video data... have generally confirmed the known details for the stronger Southern delta-Aquarid (SDA) and CAP maxima, but the SIA and NIA did not appear at all clearly, unsurprising given their borderline-visible ZHRs. The greatest oddity was the NDA, for which no distinct maximum could be traced, and whose ZHRs were never better than ~ 3. A recent investigation of the ecliptical radiants showed that what was regarded as the NDA radiant is in fact entirely within the radiant area of the Antihelion Source... The showers SIA, NIA, and NDA are no longer included in the new Working List for 2007."
The Antihelion Source (ANT), the ecliptical activity, produces a ZHR of about 3 meteors per hour, with an average velocity of about 30 km per second. A map showing the movement of the radiant throughout the month can be found at http://www.imo.net/calendar/2007
So - we no longer need to watch for these other (previously monitored) Aquarid meteors. However, plotting is still encouraged for the south delta Aquarids, the Antihelion meteors, and the alpha Capricornids (discussed in the next section), as they all originate in the same general area of the sky.
If you want to help record visual data for the meteor researchers, check out our NAMN Observing Guide for information on what to record. Our Guide can be found at http://www.namnmeteors.org/guide.html. We record such info as the time a meteor occurred, its magnitude (brightness), the shower it belongs to, its speed, and other comments such as train left behind, or color. General information to record includes such things as how dark your perceived sky is (limiting magnitude), and comments on weather and cloud cover. If you have any questions, drop a note to the NAMN Coordinator at meteors@comcast.net
For visual observers, NAMN has a set of 4 star charts to help you judge the brightness (magnitude) of the meteors you see. They are also a great tool for new observers to help you learn your constellations better. The charts can be printed off from http://www.namnmeteors.org/charts.html. Set your printer to landscape mode.
Forms to record your observations can be found at
http://www.namnmeteors.org/namn_form.html and
http://www.namnmeteors.org/appendixC.html
For those of you interested in plotting your meteors (recommended for serious observations), special IMO plotting maps can be ordered through Robert Lunsford of the International Meteor Organization. For details, contact him directly at lunro.imo.usa@cox.net
The June Bootids (JBO), although having peaked June 27th, are visible until about July 2nd. These are slow meteors with a velocity of about 18 km/sec. ZHR rates are variable. A map showing the radiant is available at http://www.imo.net/calendar/2006/spring
Several other July showers that were previously on the IMO Working List are also missing from the 2007 list: the Pegasids (JPE) and the July Phoenicids (PHE). When activity has been low over an extended period of time, the IMO will often remove a shower from their current Working List. The IMO Meteor Shower Calendar is prepared "as a means of helping observers deal with reality by highlighting times when a particular effort might most usefully be employed."
The Pisces Austrinids (PAU) peak about July 28th but can be seen from about July 15th to August 10th. These are average velocity meteors at about 35 km/sec. The radiant at the peak 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. ZHR rates are about 5 meteors per hour at maximum. For a map showing the movement of the radiant, check out http://www.imo.net/calendar/2006/summer
The alpha Capricornids (CAP) peak about July 30 and range from about July 3rd to August 15th. These are wonderful, slow meteors, with a velocity of about 23 km/sec. On July 30th, at maximum, the radiant will be at 307 degrees, ie. RA 20h 28.2m, Dec -10, which is about 3 degrees up to the left of the star alpha Capricornus, the top right star of the triangle of Capricornus. ZHR rates at the peak are about 4 meteors per hour. For movement of the radiant, check out the map on the IMO website at http://www.imo.net/calendar/2007. According to the IMO in their annual Meteor Shower Calendar, the alpha-Capricornids "are noted for their bright - at times fireball-class - events, which, combined with their low apparent velocity, can make some of these objects among the most impressive and attractive an observer could wish for."
Lastly, although observers tend to think of Perseids (PER) as an August shower, they start to become active about July 17th. They run through until about August 24th, with a peak around August 13th. These are fast meteors with a velocity of about 59 km/sec. ZHR rates around August 13th will be about 100 meteors per hour. Rates in July will be much lower. This shower lasts a long time - and the radiant moves quite a distance across the sky, a little bit each night. Check out this movement on the IMO chart at http://www.imo.net/calendar/2007
For other July minor showers not on the International Meteor Organization's 'Working List of Visual Meteor Showers', and for a wealth of historical information on all showers, check out Gary Kronk's 'Meteor Showers Online' website at http://meteorshowersonline.com
Besides July's main activity, and other minor showers, there is also sporadic meteor activity. This sporadic meteor activity is about 7 meteors per hour visible to the unaided eye. Some of these are random and some belong to old untraceable meteor showers.
The magnitudes of the planets just before mid-month are as follows:
Venus -4.3 Jupiter -2.5 Saturn 0.6 Mars 0.6
For a sky chart showing the positions of these planets in July, go to http://www.heavens-above.com, 'Select' your country, type in the name of your nearest city, and then go to 'Whole Sky Chart'. Pick 'black on white' before printing. The 'Heavens Above' website will also tell you when to look to see the ISS, the International Space Station, go over your observing site.
The phases of the moon for July are as follows:
Sat. July 7 last quarter Sat. July 14 new moon Sun. July 22 first quarter Mon. July 30 full moonOn July 16th, Saturn will be 0.04 degrees north of the moon, with an occultation visible in Hawaii, and western parts of South America.
For phases of the moon, a great monthly moon calendar can be printed off from http://stardate.org/nightsky/moon. For the NASA kids' calendar for July, go to http://spaceplace.nasa.gov/en/kids/calendar.shtml
For up to date info on what's happening in the sky right now, check out 'SpaceWeather' at http://www.spaceweather.com
Lastly, for some great sky maps showing not only the stars, but the ancient mythical drawings superimposed, check out Jan Wisniewski's website at http://www.astrosurf.com/jwisn/constellations.htm
August 9-13, 2007, Mount Forest, Ontario, Canada...
Starfest 2007, Canada's largest amateur astronomical observing convention,
will be held at the River Place Campground, near Mount Forest, Ontario.
This year's theme is 'The Universe in Motion' - and covers many different
fields of astronomy. There will be a panel discussion on 'McNaught: The
'Tail' of a Great Comet', chaired by well-known astronomy writer Terence
Dickinson. On meteors, there will be a talk by Dr. Peter Brown of the
University of Western Ontario Meteor Physics Group on the 'Southern Ontario
Meteor Network'. Details on all the many speakers, and convention info, can
be found online at
http://www.nyaa-starfest.com
August 13-17, 2007, Tucson, Arizona, U.S.A...
The 70th Annual Meeting of the Meteoritical Society will be held in Tucson,
Arizona. Special sessions will be held on meteor craters and impacts,
chondrules and chondrule formation, protoplanetary dust, and the study of
cosmogenic radionuclides, with other sessions on meteorites, asteroids and
comets, and high and low temperature parent body processes. A 3-day
post-conference field trip will be held to the Barringer Meteorite Crater,
Sunset Crater Volcanic National Monument, and the Grand Canyon. For
information, contact Elizabeth Wagganer of the Lunar and Planetary Institute
at
wagganer@lpi.usra.edu and check out the conference website at
http://www.lpi.usra.edu/meetings/metsoc2007
Note: check out the online abstracts for the conference at http://www.lpi.usra.edu/meetings/metsoc2007/metsoc2007.authorindex.shtml. Click on the 4-digit code to read the ones that interest you...
September 6-9, 2007, Ivy, Ontario, Canada...
HSP 2007, the Huronia Star Party, a small but growing astronomical
gathering, will be held about an hour's drive north of Toronto, Ontario, at
Camp Saulaine. Dr. Peter Brown of the University of Western Ontario Meteor
Physics Group will give several talks - 'Impacts of Large Bolides as
Observed by Earth Orbiting Satellite and Infrasound Networks' and 'The Fall
and Recovery of the Tagish Lake Meteorite'. Details on the other speakers,
and on this casual but informative astronomical gathering, can be found at
http://www.cois.on.ca/~ssaa
For information on upcoming astronomy meetings, see: "International Astronomy Meetings List" at http://cadcwww.hia.nrc.ca/meetings
If you know of other astronomical meetings where talks on meteors will be given, please drop a note to the NAMN Coordinator and let us know!
NAMN email: namn@namnmeteors.org
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
Ottawa, Ontario, Canada
Writer, NAMN Notes
Lew Gramer, dedalus@alum.mit.edu
Homestead, Florida, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'
Kevin Kilkenny,
namnfireball@earthlink.net
Staten Island, New York, USA
Coordinator, Fireballs and Meteorites
Back issues of NAMN Notes can be found on-line at the NAMN website
and in the MeteorObs archives at:
http://www.meteorobs.org
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.mit.edu