Estimated distances to 1.33 billion stars in Gaia DR2
Short Name:
gdr2dist scs
Date:
27 Dec 2024 08:31:05
Publisher:
The GAVO DC team
Description:
This catalogue provides distances estimates (and uncertainties therein)
for 1.33 billion stars over the whole sky brighter than about G=20.7.
These have been estimated using the parallaxes (and their uncertainties)
from Gaia DR2. A Bayesian procedure was used involving a prior
with a single parameter L(l,b), which varies smoothly with Galactic
longitude and latitude according to a Galaxy model. The posterior is
summarized with a point estimate (usually the mode) and a confidence
interval (usually the 68% highest density interval). The estimation
procedure is described in detail in the `accompanying paper`_,
which also analyses the catalogue content.
.. _accompanying paper: http://www.mpia.de/homes/calj/gdr2_distances.html
As stars in open star clusters are formed from the same matter at the
same time and have only a small velocity dispersion, it is relatively
easy to identify them from the background stars. In this tutorial, we
will identify the members of the Pleiades kinematically and get an
idea of our success by examining a color-magnitude diagram using
TOPCAT, Aladin, and a few VO services.
This tutorial uses data from Gaia DR2 to lead you through some of the
capabilities of TOPCAT and STILTS. Use cases covered include a studies
of the globular cluster M4 in proper motion space and the open cluster
Hyades in the full phase space, matches between Gaia and HST data, and
the creation of Hertzsprung-Russell diagrams.
This service returns the most important Gaia DR3 gaia_source columns
together with robust geometric and photogeometric distances for the
~1.47 billion objects in Bailer-Jones et al's distance catalogue.
This catalogue is a simulation of the Gaia EDR3 stellar content using
Galaxia (a tool to sample stars from a Besancon-like Milky Way model),
3d dust extinction maps and the latest PARSEC Isochrones. It is
mimicking the Gaia DR2 data model and an apparent magnitude limit of
G=20,7. Extinctions and photometry in different bands have also been
included in a supplementary table as well as uncertainty estimates
using scaled GDR2 errors. Additional magnitude limit per HEALpix maps
are provided, based on the mode in the magnitude distribution of Gaia
DR2 data.
This is a form-based service allowing users to run simple
queries against GAVO Data Center's ivoa.obscore table, with
some nods to users looking of data near the optical waveband.
For serious use, the `obscore table`_ should be queried through
TAP.
Note that queries without spatial constraints may take time out. You
probably ought to switch to async TAP if you really want to run such
queries.
.. _obscore table: /tableinfo/ivoa.obscore?tapinfo=true
Geometric and photogeometric distances to 1.47 billion stars in Gaia
Early Data Release 3 (eDR3)
Short Name:
gedr3dist.main
Date:
27 Dec 2024 08:31:06
Publisher:
The GAVO DC team
Description:
We estimate the distance from the Sun to sources in Gaia eDR3 that have
parallaxes. We provide two types of distance estimate, together with
their corresponding asymmetric uncertainties, using Bayesian posterior
density functions that we sample for each source. Our prior is based
on a detailed model of the 3D spatial, colour, and magnitude
distribution of stars in our Galaxy that includes a 3D map of
interstellar extinction.
The first type of distance estimate is purely geometric, in that it only
makes use of the Gaia parallax and parallax uncertainty. This uses a
direction-dependent distance prior derived from our Galaxy model. The
second type of distance estimate is photogeometric: in addition to
parallax it also uses the source's G-band magnitude and BP-RP
colour. This type of estimate uses the geometric prior together with a
direction-dependent and colour-dependent prior on the absolute magnitude
of the star.
Our distance estimate and uncertainties are quantiles, so are invariant
under logarithmic transformations. This means that our median estimate
of the distance can be used to give the median estimate of the distance
modulus, and likewise for the uncertainties.
For applications that cannot be satisfied through TAP, you can download
a `full table dump`_.
.. _full table dump: /gedr3dist/q/download/form
Identifying Brown Dwarf candidates in 2MASS and SDSS
Date:
27 Dec 2024 08:31:02
Publisher:
The GAVO DC team
Description:
This tutorial is a comprehensive scientific usecase in which brown
dwarf candidates in 2MASS and SDSS are identyfied. The surveys are
queried using ADQL, and unncertainties in the data are solved with
TOPCAT and Aladin.
Introduction to Simulation Databases - Density Fields and Dark Matter
Halos
Date:
27 Dec 2024 08:31:06
Publisher:
The GAVO DC team
Description:
This tutorial was created for a physics teacher workshop (~ high
school level). It shows how to extract density fields and information
on dark matter halos from the CosmoSim database using SQL queries. It
is optimized for brevity.
![To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to GAVO's ADQL course. For details, see the `Creative Commons CC0 1.0 Public Domain dedication <http://creativecommons.org/publicdomain/zero/1.0/>`_. Of course, you should still give proper credit when using this data as required by good scientific practice. .. image:: /static/img/cc0.png :alt: [CC0]](/registry-search/?f%5BcontentLevel_facet%5D%5B%5D=Research&f%5Bpublisher_facet_trim%5D%5B%5D=The+GAVO+DC+team&f%5Brights_facet%5D%5B%5D=To+the+extent+possible+under+law%2C+the+publisher+has+waived+all+copyright+and+related+or+neighboring+rights+to+GAVO%27s+ADQL+course.++For+details%2C+see+the+%60Creative+Commons+CC0+1.0+Public+Domain+dedication+%3Chttp%3A%2F%2Fcreativecommons.org%2Fpublicdomain%2Fzero%2F1.0%2F%3E%60_.++Of+course%2C+you+should+still+give+proper+credit+when+using+this+data+as+required+by+good+scientific+practice.%0A%0A..+image%3A%3A+%2Fstatic%2Fimg%2Fcc0.png%0A+++%3Aalt%3A+%5BCC0%5D%0A%0A){kind=link}
![OpenNGC is licensed under the `Creative Commons Attribution Share-Alike 4.0 License <http://creativecommons.org/licenses/by-sa/4.0/>`_ .. image:: /static/img/ccbysa.png :alt: [CC-BY-SA]](/registry-search/?f%5BcontentLevel_facet%5D%5B%5D=Research&f%5Bpublisher_facet_trim%5D%5B%5D=The+GAVO+DC+team&f%5Brights_facet%5D%5B%5D=OpenNGC+is+licensed+under+the+%60Creative+Commons+Attribution+Share-Alike+4.0+License+%3Chttp%3A%2F%2Fcreativecommons.org%2Flicenses%2Fby-sa%2F4.0%2F%3E%60_%0A%0A..+image%3A%3A+%2Fstatic%2Fimg%2Fccbysa.png%0A+++%3Aalt%3A+%5BCC-BY-SA%5D%0A){kind=link}