Re: Survey Strategy

[Tom Droege <tdroege2@earthlink.net>]

Rob and all,

Yes, Arne's scheme looks OK to me and he is the expert.  But the present 
Mark IVs will not do very well at it because they cannot point accurately 
in declination.

I have been worrying about this myself since I got TOM2 and TOM3 running 
and see how good the dec. drive is.  It is much worse than I thought.  So 
something needs to be done.

I have been designing a fix that could be put in place in the field.  I 
think it will work OK and get the pointing down to a few minutes in 
declination.

What will then be needed is software that is capable of doing a program 
such as described by Arne.  I think the particular sky map used is 
unimportant.  Probably we should all use the same one.  I think a 4 degree 
grid is just about right.  We get about 4.2 degrees of field and with a 
better dec. drive the .2 overlap should be enough.

Now that I have looked at a lot of data, I think it is important to point 
at exactly the same spot for each frame with a different epoch.  The data 
will not be as consistent if stars move around in position in the 
frame.  This just hides absolute accuracy, but that is life.  By matching 
position in frames we will do better in relative accuracy, and that is what 
is needed to detect variables.

OK, gang, here are the projects:

1) Get a field kit out to upgrade the dec. pointing.

2) Get table driven software out that will allow following a program such 
as that described by Arne in TN 48.

I will do 1)

Tom Droege

At 09:36 PM 10/3/02 -0600, you wrote:

>Just looking around in the Tech notes, and ran across 
>http://www.tass-survey.org/tass/technotes/tn0048.html from Arne.  This 
>still a good strategy?  Does anyone have a copy of "skymap.txt", as it 
>doesn't reside on Arne's FTP site any more...
>
>Thanks,
>Rob