Abstract:
The photometric accuracy in the near-infrared (NIR) wavelength range (0.9–2.6 lm) is strongly
affected by the variability of atmospheric transmission. The Infrared Working Group (IRWG) has recommended filters that help alleviate this issue and provide a common standard of NIR filtersets across different
observatories. However, accurate implementation of these filters are yet to be available to astronomers. In the
meantime, InGaAs based detectors have emerged as a viable option for small and medium telescopes. The
present work explores the combination of IRWG filtersets with InGaAs detectors. A few commercially
available filtersets that approximate the IRWG profile are compared. Design of more accurate IRWG
filtersets suitable for the InGaAs sensitivity range is undertaken using an open-source filter design software –
OpenFilters. Along with the photometric filters iZ, iJ and iH, design of a few useful narrow band filters is
also presented. These filters present opportunities for small and medium telescopes for dedicated long-term
observation of interesting infrared sources.
