2015-07-16T09:19:00
100
The HSOY Catalog
HSOY is a catalog of 583'001'653 objects with precise astrometry based on
PPMXL and Gaia DR1. Typical formal errors at mean epoch in proper motion are
below 1 mas/yr for objects brighter than 10 mag, and about 5 mas/yr at the
faint end (about 20 mag). South of -30 degrees, astrometry is significantly
worse. HSOY also contains, where available, USNO-B, Gaia, and 2MASS
photometry. HSOY's positions and proper motions are given for epoch J2000.
The catalog becomes severely incomplete faintwards of 16 mag in the G-band.
The mean epochs are typically very close to Gaia's J2015.
HSOY still contains about 0.7% spurious close
"binaries" (non-matched stars) from the original USNO-B (marked with non-NULL
clone). Also, failed matches within Gaia DR1 contribute another 1.5% spurious
pairs (marked with non-NULL comp). In both cases, astrometry presumably is
sub-standard.
More information is available at http://dc.g-vo.org/hsoy.
Demleitner, M.; Röser, S.; Altmann, M.; Bastian, U.;
Schilbach, E.
stars
surveys
astrometry
proper-motions
Research
Gaia
2017A&A...600L...4A
10.21938/HP1ASPBYWElyXb6qdqyolg
Added a column no_sc to mark objects without a counterpart in
SuperCOSMOS; these are presumably spurious, and filtering on
no_sc is NULL significantly improves proper motion statistics.
Optical
2000-01-01 2000-01-01
0/0-11
8.277e-20 5.369e-19
150 mas/yr are left, well within a factor
of two of the gold standard set by LSPM.
Here are comparisons of the distributions of total proper motions in
HSOY for all (blue) and ``no_sc IS NULL`` (red) objects. Top or left
is for the total catalog, bottom or right just the northern sky.
.. image:: /\rdId/q/static/pm_histograms.png
.. image:: /\rdId/q/static/pm_histograms_north.png
To get an idea of where the obvious problem on the southern sky comes from,
see this density map of stars faster than 150 mas/yr in HEALPixes of order
6, plotted in galactic coordinates. Only objects for which all of no_sc,
comp, and clone are NULL are shown. Note that the scale on the aux axis is
logarithmic:
.. image:: /\rdId/q/static/highpm_density.png
Essentially, in areas so crowded that almost any movement of a star will
hit another (within our match criteria) there will be many spurious
high-pm stars, in particular when there are many spurious sources to begin
with (plate borders). In sufficient distance from the bulge and the
Magellanic clouds, high proper motions in HSOY should be fairly reliable
when filtering out the suspicious (no_sc, clone, comp) objects.
(4) HSOY inherits the USNO photometry in B, R, and I. It has many known
issues (including, but not limited to, ridiculous values like 65.47
shown in the table above). Do not lightly use b1mag, b2mag, r1mag, r2mag,
and imag, as many of them are invalid.
(5) At the bright end, HSOY is severely incomplete. This reflects
the corresponding incompleteness of Gaia DR1.
Trivia
------
The primary key of HSOY is the tuple (ipix,comp). The suggested reference
to a HSOY object is "HSOY .0" when comp is NULL, and "HSOY
." otherwise.
If you want to cite HSOY, please see `our citation advice`_.
.. _HSOY resource descriptor: http://svn.ari.uni-heidelberg.de/svn/gavo/hdinputs/hsoy/q.rd
.. _our citation advice: /hsoy/q/q/howtocite
]]>
Hsoy Object Catalog
During the construction of USNO-B, numerous observations
were not matched properly. As a result, at least 10% of USNO-B objects
are spurious. Most of these carried over into PPMXL. Since many
of these objects have completely errneous proper motions, much fewer
will be in HSOY. However, they are present, and they are characterised
by multiple PPMXL objects being matched to one Gaia object.
Since PPMXL's resolution is much worse than Gaia's, these will almost
always be spurious; also, since the Gaia position is fixed in
both solutions, their paths will cross fairly near to J2015.0.
Download guard for hsoy dump
res/downloadguard.html
from gavo import svcs
if inputTable.getParam("input")=="yes":
raise svcs.WebRedirect(
"http://vo.ari.uni-heidelberg.de/hsoy/hsoy.dump.xz?")
else:
raise base.ValidationError("This must be 'yes' (without any"
" quotes)", "input")
HSOY SCS
static
testQuery.ra: 31.9
testQuery.dec: 61.7
q/scs.xml
rows = self.getVOTableRows()
self.assertEqual(len(rows), 1)
self.assertEqual(rows[0]["hsoyid"], "HSOY 5055227856149121395.0")
self.assertAlmostEqual(rows[0]["e_phot_g_mean_mag"],
0.00177645)
download/form
self.assertHasStrings("You are about to download HSOY",
"I read the warning</label>")
download/form
self.assertHeader("location",
"http://vo.ari.uni-heidelberg.de/hsoy/hsoy.dump.xz?")
self.assertHTTPStatus(301)
http://vo.ari.uni-heidelberg.de/hsoy/hsoy.dump.xz?
self.assertHTTPStatus(200)