Viewing Tool Help
The Web-based tool, Viewing, consists of three components, in addition to the user interface. These components are
Viewing is a Web interface for the viewing command-line utility developed by Dr. Koji Mukai. It calculates the seasonal viewing windows, as determined by the Sun angle constraints of various observatories. Viewing can also provide visibility window restrictions due to the angle with respect to the Moon, which is currently implemented for Swift. Orbital pole restrictions have also been implemented for Swift. A target near of the orbital poles of the Swift orbit will violate its Earth constraint at all times. We provide the approximate times when such a target is too close to the orbital pole, based on an extrapolation of the Swift orbit. More precise constraints are available from the Swift MOC within ~10 days of an observation, using the up-to-date ephemeris for the satellite's orbit.
Given the nature of the tool, this should be used only to check for the approximate visibility windows. Internally, the Sun angle is calculated in 1-day steps, which limits the accuracy of the results. For time-critical observations near the edge of a viewing window, consult the respective mission for authoritative limits.
In the case of XMM-Newton, for which other constraints play an essential role, we have incorporated the visibility tool written by the XMM-Newton SOC.
The range of dates checked by the Web interface goes from the current date to two years in the future. That applies to all missions supported by Viewing except for XMM-Newton, whose range can vary from one to two years.
This integrated Web version of the Viewing Tool was developed and is maintained by Edward J. Sabol.
Version 3.3b of the command-line tool, viewing, is available from
Download the files viewing3_3b.tar.gz and viewing_install.guide.
This file was last modified on Monday, 28-Sep-2015 21:05:24 EDT
HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public