The Earth passed through an unexpected filament from Comet 109P/Swift-Tuttle, causing a spectacular enhancement of the Perseids on Saturday morning August 14 beginning around 0700 UT and continuing at least until 0945 UT when morning twilight began interfering with our observations. This is some 35 hours after the traditional peak (filament was at solar longitude ~141.5˚, whereas the traditional peak is at 140.0˚ – 140.1˚). Paul Martsching and I were observing NE of Ames, Iowa and saw single-observer observed rates of 40 to 60+ meteors per hour for an extended period. Many were bright (0th and 1st magnitude, some brighter). Paul’s peak hourly rate was 64 Perseids during the hour 0845 – 0945 UT.
The dip in the meteor counts around 0830 looks to be real, and appears to be corroborated by the radio meteor counts from Germany (shown at the top of this article). This could be due to a dip in the brighter meteor rate (but not the fainter ones we couldn’t see), or perhaps it was a dip in the overall rate as the Earth passed through two “strands” of the meteoroid filament.
The IMO website reports the following:
“CBET 5016 (Jenniskens, 2021) states the peak was reached on Aug. 14, 08h02m UT (solar longitude 141.474 ± 0.005 degrees (equinox J2000.0)), with maximum ZHR between 130 ± 20 (calculated from CAMS Texas and California networks) and 210 ± 20 (calculated by K. Miskotte (DMS) from Pierre Martin’s visual observations) in good agreement with values calculated by H. Ogawa of the International Project for Radio Meteor Observation from radio forward scatter meteor observations. According to Peter Jenniskens (MeteorNews (b)), this probable filament may have been crossed over the last years, especially in 2018 (ZHR ~ 25 at solar longitude 140.95°) and 2019 (ZHR ~ 30 at solar longitude 141.02°) .”
Paul Martsching kept a detailed visual record of the outburst. He writes, “Apparently the ZHR was around double what we actually saw. The brightness index indicates a lot of faint meteors.”
Paul writes, “The rate went up to ~ 60/hour for nearly an hour; then fell back to ~ 40/hour for 45 minutes; then went back up to ~75/hour for 45 minutes; then seemed to be declining as morning twilight was interfering.”
Paul’s detailed log sheets are shown at the end of this article.
Meteor outbursts like this are rare, but they do occur from time to time. In the future, it would be nice if some of the automated meteor camera systems around the world could do some real-time processing in order to immediately alert visual observers of any outburst in progress, similar to what has often been done for auroral displays
Paul uses a talking clock and a steno pad to record the details of the meteors he sees, observing conditions, etc., without taking his eyes off the sky or needing to use a flashlight. He rolls a rubber band down the page to act as a guide for the pencil.
I have used a digital tape recorder with an external microphone that can be turned on and off for each event, and a talking clock. Unfortunately, I lost all that equipment in the Houston Memorial Day Weekend flood in 2015.
I am looking for a digital voice recorder that records the time each activation of the external microphone occurs. In other words, when I later play back each meteor description audio “snippet”, I want to be able to know exactly what the time was when the audio was recorded, thus eliminating the need for a talking clock. Does any such device exist?
A number of automated meteor cameras captured this outburst, but nothing can compare with seeing it visually under excellent conditions! I hope many others saw this event, but I suspect most visual observers did not go out, since it was after the predicted peak nights of Aug 11/12 and 12/13. A nice surprise, and on a weekend, too!