[vsnet-chat 5768] Re: [AAVSO-DIS] survey, pixy etc

[Brian Skiff <Brian.Skiff@lowell.edu>]

     Maciej wrote:

>>  -the red stars are much brighter (the chip is very sensive in red?)

     Yes, the chip is very red-sensitive, so unfiltered magnitudes of
red stars especially will be difficult to compare with others (visual, V,
even R filter).

>>  -few times software failed identification variable stars and ids faint
>>  ones as bright etc.

     There could be many reasons for this:  poor coordinates for the
variables, crowding, poor solution for the coordinates derived from the
CCD frames, etc.  What are you doing about flat-field corrections?
What does Pixy2 do as far as calibration?  With your likely magnitude
limits and image scale, you might get reasonable consistency by using
Tycho-2 photometry for mag. 7-9 stars adjusted to standard R.  And thus
you would report R magnitudes, which should be fairly close for variables
with B-V < 1.0 or so.

\Brian

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