Flare fraction in run 9128 (zoomed in part)
During IceCube drilling we observed high rates in Amanda data taking. For an early investigation see special page. After this we have tried to look out for effects by VLF or SuperDARN in live- and dead-time data extracted from the nano-DSTs but have seen no real effects sofar. We have specifically looked for VLF effects by investigating the rate in one minute bins but see no rate increase at the VLF-times (:06, :21, :36, :51).
However, in monitoring data Per Olof saw strange effects in the flare fraction indicators as shown below. Files were approximately 8 minutes long and VLF turned on every 15 minutes which matches the picture of every second bin high with occasional shifts due to the small mismatch of bin size and VLF period.
Recently Xinhua Bai saw high rated occuring in run 9134 while monitoring. I made a blow up with raw number of events per minute below. Note logarithmic y-scale! The normal level is about 5400 events/min which went up almost 5-fold in the peaks.
I skipped files 75-78, 103, and 106-113 with rates up to 330 Hz and as can be seen there were some very sharp peaks hiding in seemingly good files besides one longer (thats why my file list includes some more files). It does not look as VLF but what is is?
As a warning I have already seen files with 250 Hz in run 9136. Below I enlarge the region from 19:20 to 20:00 (UTC) in day 43. During the period 19:39-19:44 something happened. Perhaps the South Pole crew can tell us what?
Btw, I am missing nano-DSTs between run 9112 file 363 and run 9124 file 36. Does anyone know if they will ever appear in the normal store at Madison? Having the nano-DST it would be nice not to have to dig out data after the season (a small amount of files, and probably at least one run, is missing for 2004-data).