[vsnet-alert 15338] Re: Spectroscopy of the PNV J23080471+6046521
bas at lowell.edu
Sun Feb 3 05:52:22 JST 2013
On Sat, 2013-02-02 at 20:27 +0000, Patrick Schmeer wrote:
> The SDSS Photometric Catalog, Release 8
> (Adelman-McCarthy+, 2011) lists two mag 23
> (g filter) stellar sources within 0.3" of
> the nova's reported position.
These are simply detections of the same object
on two dates. SDSS DR8 shows individual results from the
various sweeps of the same region, so sometimes there
will be many such entries in some parts of the sky.
Note also that both the DR8 astrometry and photometry,
particularly in the far-north, is less good than DR7
by admission of the DR8 Web pages themselves. This results
from the adoption of UCAC3 for the astrometry (much less good
than UCAC2), and due to an error in the treatment of the
sky background for the photometry, which is important for
extremely faint objects like this one. In general I would
adopt DR7 data unless there is some compelling reason to
use DR8, such as no DR7 coverage, or a spectrum is available
only via DR8.
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