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. 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.

  • 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 Aug./Sep. 2018 to include the most recent NICER responses and background files.

    • 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 1 proposals.


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): This is the most recent RMF, and is also available within CALDB.

  • NICER Ancillary Response File (ARF): This is the most recent ARF, and is also available within CALDB.

  • NICER Background PI: Example background spectral file.
    • nixtiback20180810.pi

    • This file reproduces a "typical" NICER non-source count spectrum, including particle-induced and cosmic diffuse X-ray background. A model consisting of a broken power-law and six Gaussians was fit to several datasets drawn from blank-sky and soft-source observations. A simulated 1 Msec spectrum was then created from the resulting model.

      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.

  • Gzipped tar file containing the RMF, ARF, and background PI files:

Last Updated: October 15, 2018