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- IRSA Dust Extinction Service Queries (`astroquery.ipac.irsa.irsa_dust`)

# IRSA Dust Extinction Service Queries (`astroquery.ipac.irsa.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.ipac.irsa.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.ipac.irsa.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.ipac.irsa.irsa_dust import IrsaDust
    >>> IrsaDust.list_image_types()
    ['temperature', 'ebv', '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.ipac.irsa.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.ipac.irsa.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.ipac.irsa.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
                micron                      mag                     mag
    ----------- ------ ------------------ ------- ---------------- -----
         CTIO U 0.3734              4.107   0.174            4.968  0.21
         CTIO B 0.4309              3.641   0.154            4.325 0.183
         CTIO V 0.5517              2.682   0.113             3.24 0.137
         CTIO R  0.652              2.119    0.09            2.634 0.111
         CTIO I 0.8007              1.516   0.064            1.962 0.083
       DSS-II g 0.4621              3.381   0.143            3.907 0.165
       DSS-II r 0.6546              2.088   0.088            2.649 0.112
       DSS-II i 0.8111              1.487   0.063            1.893  0.08
         SDSS u 0.3587              4.239   0.179            5.155 0.218
         SDSS g 0.4717              3.303    0.14            3.793  0.16
            ...    ...                ...     ...              ...   ...
        UKIRT K   2.19              0.302   0.013            0.367 0.016
        2MASS J   1.23              0.723   0.031            0.937  0.04
        2MASS H   1.64               0.46   0.019            0.591 0.025
       2MASS Ks   2.16               0.31   0.013            0.382 0.016
         IRAC-1   3.52              0.178   0.008             0.22 0.009
         IRAC-2   4.46              0.148   0.006            0.183 0.008
         IRAC-3   5.66               0.13   0.005            0.162 0.007
         IRAC-4   7.68              0.122   0.005            0.151 0.006
         WISE-1   3.32              0.189   0.008            0.234  0.01
         WISE-2   4.57              0.146   0.006             0.18 0.008

### 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.ipac.irsa.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
    >>> table_ebv = IrsaDust.get_query_table('2MASXJ23045666+1219223', section='ebv') # get only one section
    >>> print(table_ebv)
        ext desc     ... ext SFD min
                     ...
    ---------------- ... -----------
    E(B-V) Reddening ...      0.1099

## Troubleshooting

If you are repeatedly getting failed queries, or bad/out-of-date results, try clearing your cache:

    >>> from astroquery.ipac.irsa.irsa_dust import IrsaDust
    >>> IrsaDust.clear_cache()

If this function is unavailable, upgrade your version of astroquery. The `clear_cache` function was introduced in version 0.4.7.dev8479.

## Reference/API

### astroquery.ipac.irsa.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.ipac.irsa.irsa_dust`.