Re: Tycho-2 catalog

[Tom Droege <tdroege2@earthlink.net>]

Sorry, it was .586.  A next project for me is to get the data processing 
machine hooked up on the network to the internet.  Sigh!  I carry data 
between the two machines on bits of paper.

Tom

At 10:22 AM 1/27/03 -0700, you wrote:
>There is no bright star at that location; there is a Tycho2 star
>at 81.853 -0.586.  Did you possibly have a typo in the coordinates below?
>Arne
>
>Tom Droege wrote:
>>OK, here is the first one on my list:
>>RA 81.853
>>Dec. -0.486
>>refcat I mag 10.03
>>tass I mag  7.99
>>refcat V mag 10.957
>>This star is in the refcat that I am using.  This is selected from 
>>big_refcat.dat.  The only thing that I do is sort out the Dec. range I am 
>>covering to produce the tyc2_photom.dat to reduce the search time.  I 
>>suspect that we need a better algorithm for generating the I entries in 
>>big_refcat.dat.  I also suspect that some of the V entries should be 
>>eliminated.
>>I found an error in my program which I do not think affected this 
>>measurement so I am re-running everything.
>>I had no luck looking this up in Vizier.  Somehow I have messed up what 
>>catalogs are used and I found nothing.  I guess I need to spend a day 
>>fussing with Vizier.
>>I am not saying that the tyco2 data is wrong, only that we may need to 
>>have a better selection process for generating the refcat that we use.
>>Tom Droege
>>At 09:29 AM 1/27/03 -0700, you wrote:
>>
>>>I agree with Michael R.  As long as the Tycho2 stars that
>>>are being used have magnitudes brighter than V=10 or so,
>>>they are consistently accurate and never more than 0.05mag
>>>off in my experience (except for variables and the oddball
>>>very red star).  If you are seeing 1-2mag errors, then my
>>>guess is that you are matching to the wrong Tycho2 star.
>>>Arne
>>
>