October Notes from NAMN

NAMN Notes: October 2002

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

1. Orionids - Meteors from Halley's Comet...
2. Watch for Draconids!...
3. Other October Showers...
4. Upcoming Meetings...
5. For more info...
1. Orionids - Meteors from Halley's Comet...

October brings the Orionids - debris from Halley's Comet! The Orionids (ORI) reach a maximum on October 21st, although can be seen from about October 2nd until November 7th. Like the upcoming Leonids in November, these are fast meteors at about 66 km per second.

ZHR rates for this shower are about 20 meteors per hour. ZHR refers to Zenithal Hourly Rate and is the number of meteors, on average, that an observer would see with the unaided eye if they were out under a dark country sky, and if the radiant, the area in the sky where the meteors seem to come from, is directly overhead.

Where is the radiant for the Orionids? It moves. A map showing the movement from October 2nd to November 7th can be found on the website of the International Meteor Organization (IMO) at http://www.imo.net/calendar/cal01.html#Orionids

On the date of maximum activity, the 21st, the radiant will be at 095 degrees, ie. RA 6h 19.8m, Dec +16, which is located by following a line from the right star of the belt of Orion up through Betelgeuse, the left shoulder star, and continuing on for about the same distance again. In the IMO 2002 Meteor Shower Calendar, the maximum on the 21st is listed as being at about 15h UT, Universal Time.

But wait - the Orionids occur on full moon this year, the 'Hunter's Moon' as it is called this month. This will wash out the sky, and make fainter stars harder to see. This also means that you will see fewer faint meteors. Is it still worth observing this? Yes, definitely! The enhanced rates will last for several days around the maximum, according to the IMO, not just one night. This means that you won't always have the full moon right overhead. You can also block the moon with a tree, your house, or even something as simple as a dark umbrella!

Because the Orionids are at full moon this year, this is also a very good time to check out full moon observing - as the famous Leonids coming next month will also occur at full moon. For visual observing, check out your limiting magnitude to see how faint you can see with a bright moon. Try the umbrella trick, and check your faintest star with the moon blocked. For photography, try out your camera and tripod with various types of film to see what works best on the stars and meteors with a full moon in the sky. The Orionids are a month before Leonids. We are on countdown. Use this unique opportunity as a test run for your Leonid observing!

The parent body of the Orionid meteors is the famous Halley's Comet. Halley, of course, did not discover this comet - its appearance has been traced back to 240 B.C. However, through his studies of orbits, he was the one who noticed the similarity between this comet's orbit and those of a number of comets that had been seen before, and made the connection that all these were sightings of the same comet. For this, his name was attached for posterity!

Mark the days around October 21st on your calendar, and get out to take a look at these shooting stars from Halley's Comet!

2. Watch for Draconids!...

The Draconids (GIA), also known as the Giacobinids, reach a maximum on October 8th, and are worth watching for any surprises! These are slow meteors, at about 20 km per second - so will be really spectacular to observe. They have also been known to storm on rare occasions just like the Leonids, producing thousands of shooting stars for the observer to see! They can be seen from about October 6th to 10th.

The radiant of this shower at maximum is at 262 degrees, ie. RA 17h 28.2m, Dec +54, which is just north of the star beta Draconis, also known as Restaban, in the head of Draco. This shower is named both after the constellation from where the meteors come, and after the parent body of the meteors, Comet Giacobini-Zinner. This comet returns about every 6.61 years. For a map showing the position of the radiant, check out http://www.imo.net/calendar/cal02.html#Draconids.

The International Meteor Organization, talks about this shower in its 2002 IMO Meteor Shower Calendar:

"The Draconids are primarily a periodic shower which produced spectacular, brief, meteor storms twice last century, in 1933 and 1946, and lower rates in several other years (ZHR's about 20-500+), most recently in 1998 when the ZHR reached about 700 briefly over the Far East. Almost all the detected showers were seen in years when the stream's parent comet, 21P/Giacobini-Zinner, returned to perihelion, as last in 1998 November. The next return of the comet is in mid 2005.... However, in 1999 a wholly unexpected minor outburst was witnessed from the Far East... This could imply a peak might be seen as late as 2002 October 9, 3.15-6.30 UT, using the 1999-equivalent timing...The nearly-new Moon makes this an almost ideal year to see what the shower yields... "

3. Other October Showers...

The delta Aurigids (DAU), although having reached a maximum on September 8th, can be seen until about October 10th. These are fast meteors, with a velocity of about 64 km per second. On the 10th the radiant will be at 95 degrees, ie. RA 6h 19.8m, Dec +49, which is very near the star psi#1 Auriga. There is a questionable link between these meteors and Comet Bradfield, C/1972 E1. At maximum in early September, the ZHR rates were about 6 meteors per hour, but rates in October will be very low. For a map showing the radiant position, check out http://www.imo.net/calendar/cal02.html#delta-Aurigids.

The epsilon Geminids (EGE) reach a maximum on October 18th, but can be seen from about the 14th to 27th. On the 18th, the radiant will be at 102 degrees, ie. RA 6h 48m, Dec +27, which is several degrees north of the star epsilon Gemini, also known as Mebsuta. These are fast meteors, at about 70 km per second. These meteors might be associated with either Comet Ikeya, C/1964 N1, or Comet Nishikawa-Takamizawa-Tago, C/1987 B1. ZHR rates for this shower are about 2 meteors per hour at maximum. For a map of the radiant, check out http://www.imo.net/calendar/cal01.html#Orionids.

The northern Taurids (NTA) and southern Taurids (STA) start to become active about October 1st but do not reach maximums until early November. Both have fairly slow meteors, with the northern Taurid velocity at 29 km per second and the southern at 27 km per second. At maximum, both showers will have ZHR rates of about 5 meteors per hour, but rates in October will be much lower. On October 10th, near the time of the Draconids, the NTA radiant will be at 29 degrees, ie. RA 1h 55.8m, Dec +14, which is about 7 degrees south of the star beta Aries, the star known as Sharatan. The STA radiant on the 10th will be at 31 degrees, ie. RA 2h 4.2m, Dec +8, which is about 5 degrees north of the star alpha Pisces. These meteors are part of the Taurid stream which in turn has been associated with Comet Encke. For a map showing the movement of the Taurid radiants over October and November, check out http://www.imo.net/calendar/cal02.html#Taurids.

For information on minor showers visible in October - and there is always minor activity - check out Gary Kronk's "Comets and Meteor Showers" website at http://comets.amsmeteors.org.

Besides recognized main showers and other minor showers, there is also sporadic meteor activity in October. 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.

This month, the phases of the moon are as follows:
Sunday Oct. 6 - new moon

Sunday Oct. 13 - first quarter
Monday Oct. 21 - full moon, 'Hunter's Moon'
Tuesday Oct. 29 - last quarter
Planets at midmonth are:
Mercury, low in morning twilight at mag. -0.2
Mars in Virgo, low in morning twilight at mag. 1.8
Jupiter in Cancer at mag. -2.0
Saturn in Orion at mag. -0.1

For information on what to record when meteor observing, check out our NAMN Observing Guide at http://www.namnmeteors.org/guide.html

For recording sheets for your meteors, go to http://www.namnmeteors.org/reports.html

For some great star charts with standard stars marked, to use in estimating the brightness of the meteors you see, go to http://www.namnmeteors.org/charts.html

And - if you have any questions on observing, drop a note to our NAMN Coordinator at meteors@comcast.net

4. Upcoming Meetings...

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

5. For more info...
NAMN email: namn@atmob.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
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

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

Here's to 'Clear Skies' for October...
October 2002 NAMN Notes co-written
by Mark Davis and Cathy Hall