NuSTAR Proposals and Tools
NuSTAR was approved by NASA for a 2-year Principal Investigator (PI) mission.
Given its science phase started in late summer 2012, NuSTAR
observations are currently scheduled to end in Fall 2014. It is anticipated
that the NuSTAR Project will request an extension of the mission, including
the institution of a Guest Observer (GO) Program, in the NASA Astrophysics
Senior Review of
Operational Missions in early 2014, and that NASA's decision will be announced
in late spring 2014. If a GO Program is approved, it is anticipated that a
Request for Proposals (RfP) will be issued shortly afterwards.
Prior to this, there was an opportunity to request NuSTAR time as part
of a joint observing proposal with XMM-Newton. The community was
to apply for joint XMM-Newton and NuSTAR observation time in the XMM-Newton Cycle
13 AO which was released on 27 August 2013, and 62 such proposals were
in fact submitted. Such joint observations
are planned to begin in May 2014. More details of this AO are available in
Section 5.4.6 of the XMM-Newton Announcement of
Opportunity, Policies and Procedures document and on the
Caltech NuSTAR website.
To help potential proposers, the standard HEASARC count rate and spectral
simulations tools, WebPIMMs and WebSpec, are available. WebSpec
was updated on September 5, 2013 to include the most recent NuSTAR responses
and background files: note that there are two possible NuSTAR options,
one for the 50% extraction region and the other for the 80% extraction region.
WebPIMMS currently has an older version of the NuSTAR response but will
shortly be updated to the most recent. The NuSTAR responses
and background files can also be downloaded directly from
here and used to simulate spectra in spectral analysis software
such as XSPEC.
Other issues which proposers should take under consideration are:
- Target Visibility: The
NuSTAR Science Operations Center Target Visibility checker
allows input of the RA and Dec coordinates of a source and finds the times
when it is visible to NuSTAR subject to viewing constraints.
- Stray Light: Extremely bright X-ray sources (>100 mCrab in the
3-79 keV band) within 1 to 5 degrees of a target can cause issues with
elevated backgrounds due to stray light.
- Dead Time: NuSTAR has a triggered readout, similar to a proportional
counter but unlike a CCD, so it does not suffer from pile-up effects. However,
dead time becomes significant for sources above ~50 ct/s, and this must be
factored into integration time estimates. Quantitative estimates of the effect
of deadtime on exposure estimates can be found