NH      [Help]

Calculate the H I Column Density for a Sky Position
(Powered by HEASoft)

Use semicolons to separate multiple object names or coordinate
pairs (e.g., Cyg X-1 ; 101.295, -16.699 ; 6 45 10.8, -16 41 58)
   (Only applies to Equatorial coordinates.)


R.A. and Dec. can be entered in ddd.ddd/[s]dd.ddd or hh mm ss.s/[s]dd mm ss.s .

References: HI4PI Collaboration, N. Ben Bekhti, L. Floer, et al., 2016, Astronomy & Astrophysics, 594, A116 (HI4PI Map).
References: Kalberla et al. 2005, Astronomy & Astrophysics, 440, 775 (LAB Map).
References: Dickey & Lockman, 1990, ARAA, 28, 215 (DL Map).

nH is a web version of the nH FTOOL, which was developed by Lorella Angelini at the HEASARC. The web interface is maintained by Edward J. Sabol of the HEASARC.

Note: An alternative tool is available at the Argelander-Institut für Astronomie (AIfA). Another tool to calculate the H I and H2 column density in a given direction is available at the UK Swift Science Data Centre. (See Willingale et al. 2013, MNRAS, 431, 394 for more details.)

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