Re: Error was GSC 748-1618 period

[Michael Koppelman <lolife@bitstream.net>]

My errors on the order of 0.01 in terms of internal consistency (not in 
an absolute sense). In the past, the TASS observations and my 
observations matched up very well in an absolute sense. See 
http://www.konkoly.hu/cgi-bin/IBVS?5327

In the past our zero point has been very close. This star is fainter so 
it may not be as close. My Tycho-2 derived comp star mags are also not 
great. I'm more worried about the shape issue that Arne mentions. I'll 
dig up the TASS V-I on the var and comps today.

Michael

On Monday, February 17, 2003, at 08:28 AM, Tom Droege wrote:

> Michael worries why he can't match up the two curves more precisely.
>
> To determine whether the miss-match is expected or not, we have to 
> consider the errors.
>
> I now know a little about the tass error.  At 11.5 the internal tass 
> error is of order 0.05 mag for this data.  This is just the rms 
> scatter of points taken in V and run through the pipeline.  We don't 
> not know about the tass error when compared to standards.  I would be 
> surprised if it were zero (with some error attached).
>
> We need also to know something about the Koppelman error.  One can 
> tell a little about the internal error by looking at the scatter of 
> the measured points.  We know nothing about the Koppelman error when 
> compared to standards?  I would again be surprised if it were zero 
> (again with some error attached).
>
> Just for tass the 0.05 mag number is just a "most of the time" number. 
>  You can be unlucky and see 3 or even more times this error.
>
> So thinking about the known errors, the match looks OK to me.  I would 
> be more suspicious if it were closer to zero.