Re: Need some rough numbers.

[Tom Droege <tdroege@veriomail.com>]

Chris,

At the top of the Tass Technical Area page is a reference to Bohden 
Paczynski's paper "On The Future of Massive Variability Searches".  A lot 
of what you want to know is in this paper which is my "bible" for this 
work.  On page 4 is a curve showing the number of stars in the sky vs 
magnitude.  This gives you an answer for any reasonable magnitude.

Some time ago, Michael sent me a table from Allen's Astonphysical 
Quantities.  I keep a copy pasted on my wall and in the front cover of my 
tass technical note book.  That shows:

Stars per square degree at:

Mag             Pole            Equator
14              102             1050
15              186             2630
16              348             6025
17              600             13500

I usually find a couple of thousand stars in a frame at 3 sigma.  Arne will 
find more.

I took 400 frames two nights ago with TOM and 400 with MICHAEL.  This is a 
typical fall number here.  One should be able to get more data in December 
to January, but I have not had very many clear nights then.  I might get 
240 in the summer.  One will take more when your software is available and 
reads out the memory in less than 60 seconds.  There are a number of 
situations where you cannot overlap the memory read out, so it is important 
for it to be faster than it is with QBasic.

BTW, what is your current time for reading the memory (16 MByte) and 
writing to disk?

I get about 70 good nights per year.  Some others in this area have said 
that that is about what is to be expected.  Arne will tell you that he gets 
1000, but it is somewhat less than that.  ;^)  No doubt he has nights worth 
1000 of mine a year.

Tom Droege

At 01:53 PM 11/6/00 -0800, you wrote:

>I am going to prototype some matching algorithms and want to
>test with a realistic amount of data.
>
>As Tom and Arne are the only two to have cameras I guess this
>question is for them.
>
>How many
>   1) Stars per frame?
>   2) Frames per night?
>   3) nights of operation per year.
>
>Also, does anyone know off hand about how many stars there
>are in the whole sky at or above our detection limit of
>about Mag 17.5