Information on resource 'Bayestar17 3D Dust Mapping with Pan-STARRS 1'

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.

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

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

Services defined within this resource descriptor

Tables defined within this resource descriptor

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.

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