Everett and Howell Paper

[Tom Droege <tdroege@veriomail.com>]

The Everett and Howell paper is nice because it shows two professionals (I 
assume) doing what we are trying to do.  I like papers that I can just sit 
down and read and understand everything they are doing.  I recommend it to 
you all.  This is a very readable paper!  I congratulate the authors for 
taking the time to make it readable.

Their camera has 8k x 8k pixels.  The equivalent of 16 of our cameras, 
Wow!  So they get data 8x as fast as one of our dual cameras.  At first 
glance, it would seem that they can really outproduce us.  But wait, they 
got the camera for only 5 days, and during "bright time".  I assume "bright 
time" is when the moon is around.  I suspect that this might be their 
year's quota of time to do something like this.   I will soon have three 
systems running (6 ea 2k x 2k cameras).  I can run every clear night.  We 
also cover 16 square degrees to their one.  So while they get more stars 
per degree and go deeper, we have a chance to cover the whole 
sky.  Further, there are three more of you with systems, and a fourth is on 
the way.  So we can take data at roughly the rate of a big camera at a big 
time observatory.

So while professionals at a good site with a better camera can out produce 
tass a few nights of the year, I doubt that they will keep it up.  They 
have demonstrated what can be done.  Their data reduction appears to be 
just what we should be doing.  The results look very nice.  We will have 
more camera noise and more sky noise, etc., so I don't expect we will 
achieve their precision, but we should be close.

There exposure times are similar to what I have been taking.  Their duty 
cycle is not quite as good as ours, so we can achieve a similar duty cycle 
with the shorter exposure that seems appropriate for our conditions.

What the people that want this data tell me (e.g. Bohden Paczynski), is 
that they want someone to stick with it for a long time.  I don't think 
that most professionals can afford to do this.  Doing it once makes a nice 
paper.  They have shown that they can get to 0.002 mag for a single 
exposure, and to 0.00019 for the series of measurements.  We should be able 
to get close to these results as limited by our sky and camera noise.

Their (b) curve data is where we should be able to excel.  They state that 
"This phenomenon is relatively common in our data (occurring in a few 
percent of the stars).  A few percent is a lot of new variables to be found 
and cataloged.  To get these measured well, we just have to stick with it 
night after night.  Again, I think that this is something that 
professionals cannot afford to do.  I already have about 50 fields exposed 
56 times with many overlaps since starting serious running in 
September.  Depending on what a "few percent" means, I should have a few 
thousand type (b) stars.  It just means cranking the data through a 
pipeline to get them.  That I plan to start to do this winter when the 
viewing is lousy.  OK, I do not underestimate this work.  It will take a 
lot of fussing.  But I plan to stick with it 10 years or so.

I would bet that Everett and Howell will now go off to do specific science 
things, like searching for planets or whatever the latest science dictates.

I would again like to encourage you all to keep at this.  It is worthwhile 
science.  Probably no one else will do what we have set out to do until 
some satellite goes up that does it.  This may be receding off into the 
future as NASA will sink more and more money into the space station and 
less into real science.

Again, a very nice paper, it demonstrates what we should be doing.

Tom Droege