by Jane Houston Jones
This week I participated in a meteor counting project at Fremont Peak State Park, led by Dr. Peter Jenniskens. Mojo and I have participated in meteor counting research with Dr. Peter since 1998, mostly for the November Leonids, but when our schedule permits, for other meteor showers as well.
Meteors are the visible remnants of orbiting comets, and they tell us alot about the early solar system. Meteors are the luminous phenomena associated with the partial ablation (the loss of mass from the surface of the meteoroid by vaporization) of meteoric matter and represent the dominant pathway from space to earth. Extraterrestrial organic matter is accreted on earth by meteors. Meteors may have dominated the supply of organics to earth if organic matter survived this pathway to earth. Also, meteors supply kinetic energy that can convert inert atmospheric gases such as CO2, N2 and H2O into useful compounds.
We conduct meteor research by counting meteors while sitting on lawn chairs. Others sit in front of a computer screen and press a key to capture the spectra of a bright meteor in the camera's field of view, as viewed on another computer screen. The more data we gather and the more spectra we collect, the more we learn about meteors and their role in life on earth. This is why I enjoy participating in meteor research, it's my way to say "thank you" to a phenomenon that may have directly led to life on earth. Plus watching meteors is really fun, relaxing and educational. It is a natural way to present science outreach to family, friends and the general public while it is happening. Everybody loves a shooting star.
I arrived at about 8:00 p.m. Monday night, the third night of continuous meteor research at Fremont Peak. I also counted meteors on Saturday night/Sunday morning, and took Sunday night off to sleep. Soon we set up a video recorder to film the shower all night long. Then we set up a CCD camera with a diffraction grating over the lens to record persistent train spectrographs. Lastly, we booted up the Wmeteors software program written by my hubby Morris Jones on a laptop computer. The laptop was then connected to an 8-port multiplexer box. This box connected serial port cables to 8 mice draped over 8 chaise lounge chairs. We set up extra chairs and chaise lounges for any passers-by who might want to watch and learn about the Perseids with us. Our setup looked like a man-made Stonehenge with a temple to the laptops and cameras in the middle of the circle of colorful plastic and aluminum monoliths.
A group of 8 meteor watchers led by Dr. Peter Jenniskens continuously counted Perseids from 11:00 p.m. Monday until 5:30 a.m. Tuesday. The observing effort was a shakedown of equipment for the upcoming November Leonid meteor shower, as well as hopeful validation of Dr. Jennisken's forecasted Perseid rates. He also hoped to capture the spectra of some Perseids, which he did! See the 8/14 article in the SF Chron http://www.sfgate.com/science/
The meteor rates remained somewhat steady from moonset at about 11:00 p.m. until dawn. Each observer saw from between about 80 and 160 mostly fast and mostly bright Perseids over the entire night, depending on how many hours they counted. We each also saw between 20 and 50 sporadic meteors, and with the help of Peter and Mike, we were able to identify some of these as slow, bright Kappa Cygnids - which are active August 3 - 25, or Delta Aquarids - which are faint and medium-speed meteors visible from July 15 thru August 25. We all kept vigilant watch for the elusive Alpha Capricornids: slow bright fireballs active from July 3 through August 15.
Most people either started the evening at about 11:00 p.m. and quit at 2:00 a.m. or started at 1:00 or 2:00 a.m. and ended at 5:30 a.m. A few folks filled in here and there for breaks, too. There were plenty of really bright Perseids and a couple of them rivaled the brightness of Venus or Jupiter. These bright ones sometimes left colorful persistent trains for as long as 30 seconds, allowing one observer (usually Peter) to run to my nearby 6-inch f/5 reflector telescope fitted with a low power (23x) view using a light-weight 32mm Televue Plossl eyepiece for a look at the swirling and changing shapes of the meteor trails in the upper atmospheric winds, while the CCD camera captured the spectra.
The best meteor rates were observed during the first and last hours of our all-night session: 11:00 p.m. to midnight and from 4:00 a.m. until dawn. The best conditions were the hour before dawn when the marine layer covered the nearby city of Hollister and the transparency improved. At its best the limiting magnitude was 6.5, at worse, maybe half a degree worse, at 6.0. Well after 5:00 a.m. we were still seeing meteors whizzing by the rising planet Saturn and we gazed upon a lyin' Orion low his side in the summer morning sky. When the fog blanketed the city lights of Hollister just before dawn, we spotted another glow in the sky. Not the Milky Way but the Zodiacal Light, a cone shaped glow of dust in the ecliptic plane of the solar system. This dust is also cometary remnants and has been blown around by the solar winds, but that's another story. http://home.wanadoo.nl/marco.langbroek/zodiac.html
There was no crowd at Fremont Peak on Monday night. I think the distance from populous areas and the timing of the weeknight shower discouraged the public from observing at faraway dark sites. The observatory was open at 9:00 p.m. and Kevin and Denni Medlock from the Fremont Peak Observatory Association showed the beautiful 4 day-old waxing crescent moon and some Milky Way splenors to an appreciative but small audience of park campers and dark-sky lovers, before they closed the observatory and joined the meteor watching group.
A cluster of meteor enthusiasts from Santa Cruz joined us and sat in our extra chairs and just enjoyed the show. After several hours all their astronomical questions were answered mostly by our meteoric chatter alone. A couple took their two dogs to howl at the moon in the observatory, stayed there for a whil, and the walked past us on the way to their campsite. After 2:00 p.m. a steady trickle of sleeping bag laden zombies walked from the ridge past the observatory to their tents or cars. We saw very few cars leaving SW or Coulter parking lots at any time. I think most of the viewers stayed for the night. The all-night observing session gave us the time to chat among ourselves and ponder great questions, both cosmological and silly.
My own meteor count was 145 Persids and 50 sporadic/minor shower meteors. I saw a dozens of "wow" quality meteors. My chair was facing east most of the night and then I switched to a chair facing west for the last hour or so. I sort of looked closer to the horizon when the radiant was low in the first observing hours, but my peripheral vision took in a large swath of sky yielding many meteors. I took some breaks too, to make hot cocoa for everyone, pass out Rice Krispy Treats and to observe the North American Nebula and Uranus with nothing but my eyes.
I also performed a little keyboard duty watching for spectra-producing meteors or checking our meteor counting rates, and logging in new observers or turning over the mice to new meteor counters.
Then, as I try to do at every meteor observing session, I located two newly-discovered comets through my small telescope. Comet C/2002 04 (Hoenig) in Cepheus was my first comet of the morning, and it looked about the same as it has on my two previous looks, a large diffuse glow, but with no tail. I like to tell people this is what a comet looks like when first discovered, usually. My second morning comet was Comet C/2002/ 06 (discovered by the SOHO spacecraft August 1) in Gemini.
Between the false-dawned zodiacal light and the approaching morning, it was tough to spot and not muich to look at. After that, I resumed observing the remnants of comets as they brilliantly streaked across the morning sky.
If this sounds like fun to you, drop me a note and I'll pass your name on to Dr. Peter Jenniskens for our November Leonid project. We often try to set up meteor counting stations at three locations over a couple nights, and volunteers are most welcome! You can read all about the past Leonid missions and their results and future plans here: http://leonid.arc.nasa.gov/index.html