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

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/.

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