Editing Cosmic ray visual phenomena (section)

==Occurrences and frequencies==
There appear to be individual differences across astronauts in terms of whether they reported seeing the LF or not. While these LF were reported by many astronauts, not all astronauts have experienced them on their space missions, even if they have gone on multiple missions.<ref name="Fuglesand2006" /> For those who did report seeing these LF, how often they saw them varied across reports.<ref name="Fuglesand2006" /> On the [[Apollo 15]] mission all three astronauts recorded the same LF, which James Irwin described as "a brilliant streak across the retina".<ref name="Irwin1983">{{cite book |title=More Than Earthlings |page=63 |publisher=Pickering & Inglis |first=James B. |last=Irwin |date=1983 |isbn=978-0-7208-0565-9}}</ref>

===Frequency during missions===
On Lunar missions, once their eyes became [[Dark adaptation|adapted to the dark]], Apollo astronauts reported seeing this phenomenon once every 2.9 minutes on average.

On other space missions, astronauts reported perceiving the LF once every 6.8 minutes on average.<ref name="Fuglesand2006" /> The LF were reported to be seen primarily before the astronauts slept and in some cases disrupted sleep, as in the case of Linenger. Some astronauts pointed out that the LF were seemingly perceived more frequently as long as they were perceived at least once before and attention was directed to the perception of them. One astronaut,<ref name="Avdeev2002">{{cite journal |title=Eye light flashes on the Mir space station |journal=Acta Astronautica |first1=S. |last1=Avdeev |first2=V. |last2=Bidoli |first3=M. |last3=Casolino |first4=E. |last4=De Grandis |first5=G. |last5=Furano |first6=A. |last6=Morselli |first7=L. |last7=Narici |first8=M. P. |last8=De Pascale |first9=P. |last9=Picozza |first10=E. |last10=Reali |first11=R. |last11=Sparvoli |first12=M. |last12=Boezio |first13=P. |last13=Carlson |first14=W. |last14=Bonvicinim |first15=A. |last15=Vacchi |first16=N. |last16=Zampa |first17=G. |last17=Castellini |first18=C. |last18=Fuglesang |first19=A. |last19=Galper |first20=A. |last20=Khodarovich |first21=Y. |last21=Ozerov |first22=A. |last22=Popov |first23=N. |last23=Vavilov |first24=G. |last24=Mazzenga |first25=M. |last25=Ricci |first26=W. G. |last26=Sannita |first27=P. |last27=Spillantini |display-authors=5 |volume=50 |issue=8 |pages=511–525 |date=April 2002 |doi=10.1016/S0094-5765(01)00190-4 |pmid=11962526|bibcode=2002AcAau..50..511A }}</ref> on his first flight, only took note of the LF after being told to look out for them. These reports are not surprising considering that the LF may not stand out clearly from the background.

===Fluctuations during and across missions===
Apollo astronauts reported that they observed the phenomenon more frequently during the transit to the [[Moon]] than during the return transit to [[Earth]]. Avdeev ''et al.'' (2002) suggested that this might be due to a decrease in sensitivity to the LF over time while in space.<ref name="Avdeev2002" /> Astronauts on other missions reported a change in the rate of occurrence and intensity of the LF during the course of a mission.<ref name="Fuglesand2006" /> While some noted that the rate and intensity increased, others noted a decrease. These changes were said to take place during the first days of a mission. Other astronauts have reported changes in the rate of occurrence of the LF across missions, instead of during a mission. For example, Avdeev himself was on Mir for six months during one mission, six months during the second mission a few years later and twelve months during a third mission a couple of years after. He reported that the LF were seen less frequently with each subsequent flight.<ref name="Avdeev2002" />

Orbital altitude and inclination have also correlated positively with rate of occurrence of the LF. Fuglesang ''et al.'' (2006) have suggested that this trend could be due to the increasing particles fluxes at increasing altitudes and inclinations.<ref name="Fuglesand2006" />