IRSA Dust Extinction Service Queries (astroquery.irsa_dust)

Getting started

This module can be used to query the IRSA Dust Extinction Service.

Fetch images

Retrieve the image cut-outs for the specified object name or coordinates. The images fetched in the FITS format and the result is returned as a list of HDUList objects. For all image queries, the radius may be optionally specified. If missing the radius defaults to 5 degrees. Note that radius may be specified in any appropriate unit, however it must fall in the range of 2 to 37.5 degrees.

>>> from astroquery.irsa_dust import IrsaDust
>>> image_list = IrsaDust.get_images("m81")

Downloading http://irsa.ipac.caltech.edu//workspace/TMP_pdTImE_1525/DUST/m81.v0001/p414Dust.fits
|===========================================| 331k/331k (100.00%)        15s
Downloading http://irsa.ipac.caltech.edu//workspace/TMP_pdTImE_1525/DUST/m81.v0001/p414i100.fits
|===========================================| 331k/331k (100.00%)        13s
Downloading http://irsa.ipac.caltech.edu//workspace/TMP_pdTImE_1525/DUST/m81.v0001/p414temp.fits
|===========================================| 331k/331k (100.00%)        05s

>>> image_list

[[<astropy.io.fits.hdu.image.PrimaryHDU at 0x39b8610>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x39b8bd0>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x39bd8d0>]]

Image queries return cutouts for 3 images - E(B-V) reddening, 100 micron intensity, and dust temperature maps. If only the image of a particular type is required, then this may be specified by using the image_type keyword argument to the get_images() method. It can take on one of the three values ebv, 100um and temperature, corresponding to each of the 3 kinds of images:

>>> from astroquery.irsa_dust import IrsaDust
>>> import astropy.units as u
>>> image = IrsaDust.get_images("m81", image_type="100um",
...                             radius=2*u.deg)

Downloading http://irsa.ipac.caltech.edu//workspace/TMP_007Vob_24557/DUST/m81.v0001/p414i100.fits
|===========================================| 149k/149k (100.00%)        02s


>>> image

[[<astropy.io.fits.hdu.image.PrimaryHDU at 0x3a5a650>]]

The image types that are available can also be listed out any time:

>>> from astroquery.irsa_dust import IrsaDust
>>> IrsaDust.list_image_types()

['ebv', 'temperature', '100um']

The target may also be specified via coordinates passed as strings. Examples of acceptable coordinate strings can be found on this IRSA DUST coordinates description page.

>>> from astroquery.irsa_dust import IrsaDust
>>> import astropy.coordinates as coord
>>> import astropy.units as u
>>> image_list = IrsaDust.get_images("17h44m34s -27d59m13s", radius=2.0 * u.deg)

Downloading http://irsa.ipac.caltech.edu//workspace/TMP_46IWzq_9460/DUST/17h44m34s_-27d59m13s.v0001/p118Dust.fits
|==============================|  57k/ 57k (100.00%)        00s
Downloading http://irsa.ipac.caltech.edu//workspace/TMP_46IWzq_9460/DUST/17h44m34s_-27d59m13s.v0001/p118i100.fits
|==============================|  57k/ 57k (100.00%)        00s
Downloading http://irsa.ipac.caltech.edu//workspace/TMP_46IWzq_9460/DUST/17h44m34s_-27d59m13s.v0001/p118temp.fits
|==============================|  57k/ 57k (100.00%)        00s

A list having the download links for the FITS image may also be fetched, rather than the actual images, via the get_image_list() method. This also supports the image_type argument, in the same way as described for get_images().

>>> from astroquery.irsa_dust import IrsaDust
>>> import astropy.coordinates as coord
>>> import astropy.units as u
>>> coo = coord.SkyCoord(34.5565*u.deg, 54.2321*u.deg, frame='galactic')
>>> image_urls = IrsaDust.get_image_list(coo)
>>> image_urls

['http://irsa.ipac.caltech.edu//workspace/TMP_gB3awn_6492/DUST/34.5565_54.2321_gal.v0001/p292Dust.fits',
'http://irsa.ipac.caltech.edu//workspace/TMP_gB3awn_6492/DUST/34.5565_54.2321_gal.v0001/p292i100.fits',
'http://irsa.ipac.caltech.edu//workspace/TMP_gB3awn_6492/DUST/34.5565_54.2321_gal.v0001/p292temp.fits']

Fetching the extinction table

This fetches the extinction table as a Table. The input parameters are the same as in the queries discussed above, namely the target string and optionally a radius value:

>>> from astroquery.irsa_dust import IrsaDust
>>> import astropy.coordinates as coord
>>> import astropy.units as u
>>> # "22h57m57.5s +26d09m00.09s Equatorial B1950"
>>> coo = coord.SkyCoord("22h57m57.5s +26d09m00.09s", frame='fk4')
>>> table = IrsaDust.get_extinction_table(coo)

Downloading http://irsa.ipac.caltech.edu//workspace/TMP_wuevFn_3781/DUST/345.094229457703_26.418650782801027.v0001/extinction.tbl
|=======================================================================================| 4.4k/4.4k (100.00%)         0s

>>> print(table)

Filter_name  LamEff A_over_E_B_V_SandF A_SandF A_over_E_B_V_SFD A_SFD
            microns                      mags                    mags
----------- ------- ------------------ ------- ---------------- -----
     CTIO U  0.3734              4.107   0.229            4.968 0.277
     CTIO B  0.4309              3.641   0.203            4.325 0.241
     CTIO V  0.5517              2.682   0.149             3.24 0.181
     CTIO R   0.652              2.119   0.118            2.634 0.147
     CTIO I  0.8007              1.516   0.084            1.962 0.109
   DSS-II g  0.4621              3.381   0.188            3.907 0.218
   DSS-II r  0.6546              2.088   0.116            2.649 0.148
   DSS-II i  0.8111              1.487   0.083            1.893 0.105
     SDSS u  0.3587              4.239   0.236            5.155 0.287
     SDSS g  0.4717              3.303   0.184            3.793 0.211
     SDSS r  0.6165              2.285   0.127            2.751 0.153
     SDSS i  0.7476              1.698   0.095            2.086 0.116
     SDSS z  0.8923              1.263    0.07            1.479 0.082
    UKIRT J   1.248              0.709   0.039            0.902  0.05
    UKIRT H   1.659              0.449   0.025            0.576 0.032
    UKIRT K    2.19              0.302   0.017            0.367  0.02
    2MASS J    1.23              0.723    0.04            0.937 0.052
    2MASS H    1.64               0.46   0.026            0.591 0.033
   2MASS Ks    2.16               0.31   0.017            0.382 0.021
     IRAC-1    3.52              0.178    0.01             0.22 0.012
     IRAC-2    4.46              0.148   0.008            0.183  0.01
     IRAC-3    5.66               0.13   0.007            0.162 0.009
     IRAC-4    7.68              0.122   0.007            0.151 0.008
     WISE-1    3.32              0.189   0.011            0.234 0.013
     WISE-2    4.57              0.146   0.008             0.18  0.01

Get other query details

This fetches in a Table other additional details that may be returned in the query results. For instance additional details in the three sections - ebv, 100um and temperature as mentioned earlier and an additional section location may be fetched using the section keyword argument. If on the other hand, section is missing then the complete table with all the four sections will be returned.

>>> from astroquery.irsa_dust import IrsaDust
>>> table = IrsaDust.get_query_table('2MASXJ23045666+1219223') # get the whole table
>>> print(table)

    RA      Dec    coord sys regSize ... temp mean temp std temp max temp min
   deg      deg                deg
--------- -------- --------- ------- ... --------- -------- -------- --------
346.23608 12.32286 equ J2000     5.0 ...   17.0721   0.0345  17.1189  17.0152

# fetch only one section of the table

>>> table = IrsaDust.get_query_table('2MASXJ23045666+1219223',
...                                   section='ebv')
>>> print(table)

    ext desc     ... ext SFD min
                 ...
---------------- ... -----------
E(B-V) Reddening ...      0.1099

Reference/API

astroquery.irsa_dust Package

IRSA Galactic Dust Reddening and Extinction Query Tool

Revision History

Refactored using common API as a part of Google Summer of Code 2013.

Originally contributed by:
 David Shiga (dshiga.dev@gmail.com)

Classes

IrsaDustClass()
Conf Configuration parameters for astroquery.irsa_dust.