EXTINCTION CALCULATORS

NED's own Galactic Reddening and Extinction Calculator is incorporated in the coordinate transformation and precession calculator. To use it, enter a position in one of the accepted coordinate systems, choose the input and output equinoxes, and click "Calculate".

In addition, a query of NED By Name or By Position automatically gives Galactic extinctions for fourteen popular bandpasses (UBVRIugrizJHKL') in the Basic Data section for each object returned. This service uses the Schlafly & Finkbeiner 2011 (ApJ 737, 103, 2011) recalibration of the Schlegel, Finkbeiner & Davis 1998 (ApJ 500, 525, 1998; SFD98) extinction map. The original SFD98 extinction values are also returned for comparison purposes. NED's Basic Data additionally gives a value of A_B using the prescription given by Burstein and Heiles 1982 (1982, AJ, 87, 1165) for direct comparison with the SFD98 value given that there are some systematic differences between the two estimators. Please read the caveats for using these extinction calculators.

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NED is providing the following links to outside sites at the specific request of users and as an additional service to extragalactic researchers in general. The NED Team has not fully validated any of these calculators, and questions concerning the algorithms used, their range of application and the precision of the returned results should be directed to the original Web site creators.

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IRSA: Galactic Reddening and Extinction Calculator

IRSA, Infrared Processing and Analysis Center

This service uses the Schlegel, Finkbeiner and Davis (1998, ApJ, 500, 525) Galactic reddening maps to determine the total Galactic line-of-sight absorption for about 40 popular photometric systems including Landolt (UBVRI), Stromgren (uvby), Sloan (u'g'r'i'z') and WFPC-2.

The calculator accepts an object name or an RA/DEC position. The IRAS 100-micron map of the surrounding region is returned and a detailed listing of extinctions can be obtained by clicking the highlighted link "Reddening and Extinction by Bandpass" in the upper-right panel, entitled "E(B-V) Reddening"

Interstellar Extinction Calculator

Doug Welch, McMaster University

This calculator determines the total absorption for wavelengths between 0.10 and 3.33 um using the algorithm published by Cardelli, Clayton, and Mathis (1989, ApJ, 345, 245). Required input parameters are:

R_V the ratio of total to selective absorption at V

A_V the total absorption in magnitudes at V

W_micron the target wavelength in microns

Curator's email address: welch@physics.mcmaster.ca

Galactic HI Line-of-Sight Column-Density Calculator

P.M.W. Kalberia, Bonn University

HI column density and the complete spectrum for any position on the sky from the Leiden/Argentine/Bonn (LAB) Survey. Users can specify the desired position in either Equatorial or Galactic coordinates.

York Extinction Solver (YES)

Marshall McCall, York University

The York Extinction Solver (YES) is a facility for evaluating the Galactic or localized extinction of any celestial body in any filter from any index of reddening. Its development was motivated by a need to free extinction estimates from errors arising from shifts in effective wavelengths, which permeate astronomy. For example, it has been common practice to estimate the extinction of a disk galaxy from an estimate of reddening derived from elliptical galaxies and a reddening law derived from broad-band photometry of O and B stars without any accommodation whatsoever for the differences between the spectral energy distributions. YES facilitates the determination of the ratio of total-to-selective extinction for a target without concern as to the shape of the spectrum of the reddening probe. Further background is given by M. L. McCall 2004, AJ, 128, 2144.

Curator's email address: mccall@yorku.ca