How to Use the Galactic Dust Reddening and Extinction Service

Required fields:

• Single location: Enter an object name or coordinates. Enter the image size of the cutout region (min = 2 deg, max = 10.0 deg).

• Table Upload: Provide the name of a table (which must conform to one of the styles listed here).

Results:

• Single location mode

  The results page includes three image cutouts: E(B-V) reddening, 100 um intensity, and dust temperature. The images are displayed as jpg images, with a link "Download cutout" to the actual FITS image. The overlays are an equatorial coordinate grid, statistics area (green circle) and target location (red cross). Click on "Larger view" to view a zoomed-up version. Click on the image to change the target location to the cursor location.

  Table values refer to the target location and a small 5 arcmin radius statistics area encircling it:

  reference pixel = single pixel value of the target location
  Max = maximum pixel value within statistics area
  Min = minimum pixel value within statistics area
  Mean = mean +- RMS of the pixel distribution within statistics area
  
  The derived galactic visual extinction is also given, using an assumed ratio of total to selective extinction of 3.1.

  In Single Location mode, a separate table gives the extinction in several bandpasses, ranging from the ultraviolet (0.3 um) to the mid-infrared. Click on "Extinction by Bandpass". The filter, effective wavelength, ratio of band extinction to reddening, and the extinction in that band for the line of sight are given. For the results listed under Schlegel et al., the uv-vis extinction law is based on Cardelli et al. (1989) and O'Donnell (1994), and the mid-infrared extinction is based on the extinction law derived by Indebetouw et al. (2005).

  NEW (July 2013). Newer reddening values from Schlafly & Finkbeiner (2011) are given alongside those of Schlegel et al., though both begin with the Schlegel et al. maps. For the newer extinctions by bandpass, the uv-vis extinction law is based on Fitzpatrick (1999) and the mid-infrared extinction is from Indebetouw et al. (2005). (More uv-vis filters are available in Schlafly & Finkbeiner, Table 6.) In addition to the Spitzer IRAC filters, the two shorter wavelength WISE bands were added. Extrapolation to the longer wavelength WISE bands is too uncertain.

• Table Upload mode

  This mode allows the user to specify multiple locations on the sky. Here is an example table. The limit is 20000 rows.

  The results page gives the results for the reddening, 100 um intensity and dust temperature at the input coordinates: location coordinates, image size, target pixel value, mean and standard deviation of the pixel distribution, and the min and max of the pixel distribution.

  Both HTML and downloadable tables are provided if there are less than 50 rows. Clicking on the HTML "image cutout" button gives the FITS images (see "Single location mode" above). For the downloadable tables, click on "Download table".

  NEW (July 2013). Reddening values from Schlafly & Finkbeiner (2011) are given alongside those of Schlegel et al. (1998). See above.

Background, Technical Notes and References

See the background discussion: Galactic Dust Reddening and Extinction Service.

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