Estimates of the performance of IRPS are given below. Five standard broad-band filters are installed, as listed in Table 8.4. The sensitivity limits quoted are for 3 sigma after 30 minutes of integration. This is about the longest one should spend on a single measurement, but actually the sensitivity limits fluctuate because the sky brightness is not constant. In summer the longer wavelengths fare less well, and around sunspot maximum J and H are worsened.
Atmospheric extinction is slightly higher in summer and less in winter.
At J and M, the extinction is sensitive to humidity. Magnitudes are listed in the users' manual. Obviously, photometric weather is necessary to do photometry.