Table information for 'prdust.map_union'

General

Table Description: This is a view of the dust maps in the five orders, generated by splitting the larger pixels from the higher orders into HEALPixes of order 10. This means, in particular, that the spatial resolution for all pixels with original_order!=10. Use this for convenient joins to other tables.

This table is available for ADQL queries and through the TAP endpoint.

Resource Description:

A 3D map of interstellar dust reddening, covering three quarters of the sky (declinations greater than -30 degrees) out to a distance of several kiloparsecs. The map is based on high-quality stellar photometry of 800 million stars from Pan-STARRS 1 and 2MASS.

The map is available for five HEALPix levels (6 through 10), published here as separate tables, map6 through map10. A union of the coverage is provided as map_union. Use its coverage column to match against other tables.

See http://argonaut.rc.fas.harvard.edu/ for more details.

For a list of all services and tables belonging to this table's resource, see Information on resource 'Bayestar17 3D Dust Mapping with Pan-STARRS 1'

Citing this table

@MISC{vo:prdust_map_union,
  year=2018,
  title={Joined Bayestar17 3D Dust Map},
  author={Green, G.M. and Schlafly, E.F. and Finkbeiner, D. and Rix, H.-W. and Martin, N. and Burgett, W. and Draper, P.W. and Flewelling, H. and Hodapp, K. and Kaiser, N. and Kudritzki, R.-P. and Magnier, E.A. and Metcalfe, N. and Tonry, J.L. and Wainscoat, R and Waters, C.},
  url={http://dc.zah.uni-heidelberg.de/tableinfo/prdust.map_union},
  howpublished={{VO} resource provided by the {GAVO} Data Center}
}

Copyright, License, Acknowledgements

• To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to 3D Dust Maps. For details, see the Creative Commons CC0 1.0 Public Domain dedication. Of course, you should still give proper credit when using this data as required by good scientific practice.

  
• https://spdx.org/licenses/CC0-1.0.html

Resource Documentation

These tables lets you do dereddening of photometry provided you have:

• Positions
• An estimate for the distance modulus
• Some idea of how to get from E(B-V) to your extinction.

You will usually join two of the arrays in map_union to your table. Because of boring technicalities, that is a bit ideomatic; you need to compute an order-10 healpix and see if that is contained in this tables coverage. In a cartoon:

SELECT
  mytable.*,
  best_fit, grdiagnostic
FROM mytable
JOIN prdust.map_union
ON (1=ivo_interval_has(
  CAST(ivo_healpix_index(10, l, b) AS INTEGER), coverage))

Yes, you have to use galactic longitude and latitude in the arguments of ivo_healpix_index; and the odd cast is necessary because coverage contains normal integer intervals.

If you have equatorial coordinates ra and dec, on this service there's the gavo_transform user defined function to your rescue. Just write:

CAST(ivo_healpix_index(10,
  gavo_transform('ICRS', 'GALACTIC', POINT(ra, dec))
    ) AS INTEGER), coverage)

in the second argument of ivo_interval_has above.

The next step is to estimate a distance modulus. If you have a good parallax estimate and your TAP service supports the in_unit UDF, you might get away with:

5*log10(1./in_unit(parallax, 'arcsec'))-5 AS dist_mod

You will certainly want to do better than this in almost all science use cases (see 2018arXiv180409376L for a through discussion in the context of Gaia DR2).

From dist_mod, you can compute the distance bin in the best_fit and grdiagostic columns with:

ROUND((dist_mod-4)*2)+1 AS dist_mod_bin

With this, you can add an E(B-V) to a local table somewhat like this:

SELECT
        q.*,
        best_fit[dist_mod_bin] as eb_v
FROM (
        SELECT (
                CAST(ivo_healpix_index(10, l, b) AS INTEGER) AS cat_hpx,
                ROUND((dist_mod-4)*2)+1 AS dist_mod_bin,
                mytable.*
        FROM mytable) AS q
JOIN prdust.map_union
ON (1=ivo_interval_has(cat_hpx, coverage))
WHERE grdiagnostic[dist_mod_bin]<1.2

To turn E(B-V) into extinctions, there are several recipes. See, for instance 1998ApJ...500..525S.

You'll find a worked-out example on this at https://blog.g-vo.org/deredden-using-tap/.

Columns

Sorted by DB column index. [Sort alphabetically]

Columns that are parts of indices are marked like this.

VOResource

VO nerds may sometimes need VOResource XML for this table.

Notes