[Aavso-photometry] average vs. median

[Ben Davies]

Thanks to everyone for all the response on the cosmic ray thing.  Having 
read through all the links, I'm feel much better informed.  And now know 
how those worms in the image are formed.

It was not so wrong of me to think of cosmic rays as coming in from 
'above'.  The LBNL study showed that ccds in a vertical orientation have 
50% fewer (and more prominent) strikes than a ccd in the horizontal 
plane.  So probably I suffer a little less with my homemade Newtonian 
than you do with your fancy storebought RCs.  Take that <g>.  Also, it 
seems a good idea to make bias, darks, and flats (if you can) with the 
chip in a vertical position.

I didn't find any followup on the tests at Lick and Keck where the lead 
boxes unexpectedly failed to shield from gamma radiation.  Otherwise the 
tests showed that 3/8" of lead is very helpful with the gamma radiation, 
which make up 2/3s of the cosmic ray hits.

Ben Davies