Hi,
Just a quick note on astrometric errors in PS-MOPS. Right now PS-MOPS
uses a single value for the astrometric error (user configurable)
which is then weighted by each object's magnitude (the weights do not
seem to be configurable). In this way, faint objects are associated
with large errors, bright objects with small errors.
Cheers
f
On Jun 23, 2006, at 10:56 AM, Zeljko Ivezic wrote:
Kem Cook wrote:
If the astrometric error is meant to be absolute astrometric
error, then I
think that it should be more like 0.05, which is the design spec for
absolute atrometric accuracy.
Yes, except for the last magnitude where the sky noise makes it
larger (at the 5-sigma limit, V~24.5, it should be around 150 mas).
Another thing worth thinking about is that PS-MOPS does NOT use any
filter information. This means that the pipeline silently assumes
that all fields were observed in the same filter (red) even when
that
is clearly not the case.
This could be indirectly taken care of through the signal-to-noise
consideration. For typical asteroid colors, the i, z and Y band
data can be shallower by 0.2 mag, while the g band data must be
0.6 mag deeper, and the u band data ~2 mag deeper, than the r band
data in order to achieve the same SNR as the r band.
Does PS-MOPS take the same astrometric error for all the objects,
or can one specify it for each object?
Cheers,
Zeljko
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