More on the Quadrantids

Another winter storm has been moving through Arizona. As a result the past two nights have seen nothing but clouds and rain. Hopefully the meteor watch can continue again tonight.

Observations of the Quadrantids continue to be reported to the International Meteor Organization from all over the world. The plot seen below shows the geographic location of visual observers who have submitted their reports. By visual, we mean observers who only used their eyes, and not cameras, to count meteors.

Geographic distribution of Quadrantid visual reports to the International Meteor Organization (IMO). Plot from the IMO's "Quadrantids 2009" page at

This map is interesting because it tells us a lot about the state of meteor astronomy and amateur astronomy. The furthest southern observer was in Venezuela. This is due to the fact that  the Quadrantids radiate from a northern Declination of +49 degrees. This means that the Quadrantid radiant is located directly above a latitude of +49 degrees. The further south one gets the harder it is to see the Quadrantids. In  fact, they are very hard to see south of 10 degrees South and invisible south of 40 degrees South.

Due to the short duration of the Quadrantids and the frigid temperatures in the Northern Hemisphere during early January, the number of people observing the Quadrantids is much lower than the Perseids in mid-August. The majority of observers are located in Europe and North America with a few observers in Japan and the rest of Asia. The most extreme observers was Bruce McCurdy who observed from Yellowknife in the Northwest Territory of Canada. Temperatures were below -40 C (-40 F) and he was able to keep warm by observing through the open moon-roof a running and heated vehicle.

Plots of the Zenithal Hourly Rate show just how sharp the peak was. The first plot shows a period of more than a week while the second plot covers a single day centered on the peak. It is apparent that the Quadrantids produced very low rates (ZHR < 5-10) except for a period of just over 24 hours. In Europe, rates were rapidly climbing from ~30 to ~110 meteors per hour. (Again note that these rates are only valid for dark skies and when the radiant is overhead. In many locations the actual number of observable meteor was less.) The peak occurred over all of North America with a peak ZHR of ~160. Observers in Asia were able to catch the downward leg of the peak as rates dropped from ~120 to ~50. By the next night in North America, rates were only around 10 per hour.

ZHR plot of Quadrantid activity for a week or more before and after the peak. Plot from the IMO's "Quadrantids 2009" page at
ZHR plot of Quadrantid activity centered on the night of peak activity. Plot from the IMO's "Quadrantids 2009" page at

With a peak ZHR of ~160, this year’s Quadrantids were as good as they can be. From year to year, the peak rates can vary from ZHRs of 80 to 160.

We now enter a slow season for meteor observing. Rates of sporadic meteors drop to only a half dozen or so per hour and the next major shower isn’t till late April.