NICER Proposal Tools

The following documentation and applications can be used to support the preparation of NICER observing proposals:

  • NICER Mission Guide: The NICER team has developed a NICER Mission Guide document which describes NICER's technical capabilities and concept of operations.

  • Visibility: The standard HEASARC Viewing tool can be used to determine target visibilities for NICER based solely on Sun and Moon avoidance. The tool reports a "preferred" visibility window, which has a Sun angle constraint of 60-180 degrees, and a ``nominal'' visibility window, which has a Sun angle constraint of 45-180 degrees. The Moon avoidance angle is 15 degrees.

    The NICER Enhanced Visibility Calculator calculates visibilities for targets over roughly the next 2-week period taking into account ISS orientation and target occultation by ISS structures, and other relevant constraints. These visibility intervals are more accurate than visibilities based solely on Sun and Moon avoidance.

  • NICER Tips: Prospective proposers may wish to consult this page which provides NICER data analysis tips and caveats.

  • Count Rate and Spectral Simulations: The standard HEASARC count rate and spectral simulations tools, WebPIMMS and WebSpec, are available for NICER simulations. They were updated in August 2019 to include the most recent NICER responses and background files. It also corrected a bug in the prior version that significantly overestimated NICER's background rates in many circumstances.

    • The NICER responses and background files can also be downloaded directly by following the links below. These files can be used to simulate spectra in spectral analysis software such as XSPEC. They are suitable for the preparation of Cycle 2 proposals.

  • Background Estimator Tools: The NICER team has developed two independent software packages to be used as add-ons to the HEASoft software that provide detailed models of the NICER background for a given observation.

In addition, the NICER team has made available a set of files to assist users in performing XSPEC analyses of NICER data.

  • NICER Redistribution Matrix File (RMF).

  • NICER Ancillary Response File (ARF).

  • NICER Background PI: Example background spectral file.
    • nixtiback20190807.pi

    • This file reproduces a "typical" NICER non-source count spectrum, including particle-induced and cosmic diffuse X-ray background.

      The background can deviate greatly from this typical spectrum, and can do so to different degrees at low (<0.3 keV) and high energies, depending on the details of the observation and the data screening strategy that is applied.

Last Updated: July 28, 2021