Proposal Planning Toolkit: Colden Help

This is a help page specific to using Colden online. For more information, please consult the CIAO colden help page here.

Input Coordinates

The user may enter the input coordinates or resolve a Target Name using the Resolve Name button.

Coordinate System

Select the coordinate system for specifying the column direction. Colden supports the following choices:


Specify the epoch. This is enabled only if the selected Coordinate System is Equatorial(Xxxxx) or Ecliptic(Bxxxx).


Input a set of coordinates in the format of the selected coordinate system or resolve a target name which will set the RA/Dec coordinates in J2000. The supported coordinate ranges are listed below.

Target Name

Enter a valid target name and click the Resolve Name button. This will query the catalog[s] specified in the Name Resolver field. If one, and only one entry is found, the coordinates will be displayed in J2000. If no entry is found or more than one entry is retrieved, the user will be asked to modify the Target Name and try again.

Name Resolver

Name of the service or services that will be used to resolve the target name when the Resolve Name button is pressed. The services will be chosen in the specified order. For example, "NED/SIMBAD" will first search for the target name in NED and then, if the name was not found, in SIMBAD.


Select the neutral hydrogen data set. Colden supports the following choices:

Velocity Range

The Bell data set supports integrating over the full range of velocities (-550. to 550. km/s) or over a restricted range. The Bell data have a velocity resolution of about 5 km/s. Specify the range of velocities.


Galactic L2

Longitude in Galactic coordinate system, in decimal degrees (ddd.dddd).


Latitude in Galactic coordinate system, in decimal degrees (sdd.dddd)


The neutral hydrogen column density, in units of 1e+20 per cm**2.


Auxiliary explanatory comments about the computation are provided. Thursday, February 08, 2024
The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email: Smithsonian Institution, Copyright © 1998-. All rights reserved.