Astro 9 Field Trip to Bonny Doon - Oct 22/23, 2011

Our annual Astro 9 optional field trip to dark skies was held Saturday night Oct 22, joining the Santa Cruz Astronomy Club's monthly outing. We had a good turnout - Gene, Strider, Becky, Phil, among others. We imaged on the ST4000xcm + 8" SN for as long as our batteries and computers held out. We used the department's Dell, till it gave out, then Gene's Dell, ending around 2:30am.

This was also the night of Orionid Meteor Shower maximum and was saw one spectacular V=-6 Orionid which left a spectacular trail through Sculptor. Becky grabbed the Department's Nikon D40 and began taking 30 second images of the trail, and I told her to keep taking 30 second images for as long as the trail persisted. This turned out to be over an hour! It makes quite an interesting time sequence. Meteor trails are of three types; ionization trails glow from the recombination and cascading down the ground state which happens when a meteor ionizes the surrounding air. This process generally lasts only seconds or maybe a minute or two at the most. Longer-lived trails are from dust which remains and is typically lit by the sun just below the observer's horizon, near dawn or dusk. The third type is due to chemiluminescence, whereby oxygen and ozone (O3) combine, releasing photons. The reaction is catalyzed by iron deposited from the meteor. Was this meteor unusually enriched in iron? This trail lasted over an hour, far beyond what an ionization trail should do. The Orionids are fast meteors, but not as fast or as ionizing as Leonids. Leonids of this magnitude still only leave trails lasting several minutes at the very most, as I can attest both from the '66 Leonid Storm and the 2001 Leonid Storm. And those Leonids were at least as bright as this Orionid. Dust is pretty unlikely as well - it happened near local midnight; 1:30-2:30am, and could not have been lit by the sun. Peter Jenniskens feels confident it is a chemiluminscent trail.

A month after the trip, I finally got together with Becky at the Cabrillo Observatory and she figured out how to generate a .gif animation from the individual jpeg images, using Photoshop CS2 and Layers. There are a number of links on the web, we chose these instructions. Note that the meteor trail drifted to the east significantly during the hour, and I estimate the trail velocity projected onto a plane perpendicular to our line of sight to be about 80 mph.