Re: [APML] STV - Is it worth it?

["Jim Janusz" <jjanusz@ix.netcom.com>]

Hi again Michael,

I would welcome the idea of selecting the calibration star in the manual
calibrate mode.  It seems like the elegant solution to the problem and may
be the most simple solution.  You already allow us to override the guide
star selection.

I can't remember if I've ever seen it fail on one star, but it does fail on
2 or 3 as well as many.

(When you have only 2 or 3
> stars in the field and it gives the error message - try adjusting the
> exposure so that only the brightest star of the group is found on the
first
> pass and see if it works.)

I'll try that the next time it happens, normally I move the field around
until it's happy, sometimes requires 2 or 3 attempts.


Thanks for taking the time to look into this, I do appreciate it.

Jim


----- Original Message -----
From: "Michael Barber" <barber@sbig.com>
To: <astro-photo@seds.org>
Sent: Thursday, May 10, 2001 4:45 PM
Subject: Re: [APML] STV - Is it worth it?


> At 05:31 PM 5/9/01 -0700, you wrote:
>
> >I'll be waiting to hear from you.
>
> Jim:
>
> Still pondering the problem...  Because the STV tasked to identify,
> remember and calibrate on multiple stars there are possible situations
> where it can be fooled into thinking the star field is not the same as the
> one it used in the previous frame.  I think this almost never happens when
> there is only 1 star in the field (or 1 star that is significantly
brighter
> than all the rest) or when there are several stars.  It is most likely to
> be fooled when there are (a) only 2 or 3 stars or (b) many more than 8
> stars or multiple stars of similar brightness.
>
> It will take us some time to test some different situations here and see
if
> we can force it to fail in a certain configuration most of the time and
> then see what we can do to avoid it from happening.  A simple solution
> might be to add a completely manual selection of calibration star (similar
> to CCDTRACK).  Then the STV wouldn't have to think at all - just
calculate.
>  It would be up to the user to be sure it was the same star in each frame.
>
> Anyway we're working on it.   It will take a while but if you have any
> insight in the mean time please let me know.  When you have only 2 or 3
> stars in the field and it gives the error message - try adjusting the
> exposure so that only the brightest star of the group is found on the
first
> pass and see if it works.
>
> Regards,
> Michael Barber
> SBIG
>
>
>
>
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