Optical bandpass filters enable simultaneous observations by ZEUS-2
The ZEUS-2 spectrometer is able to address up to four telluric windows simultaneously by placing optical bandpass filters directly over its detector, a capability that forms the core of a scientific poster exhibited by the American Astronomical Society in January 2017. A team from Cornell University assisted by Patrick Dahlin of the University of Michigan at Ann Arbor spent the summer of 2016 testing ZEUS-2 and developing components to further improve the performance of the spectrometer.
Observations using Optical Bandpass Filters
In particular they looked at its sensitivity when detecting fine structure lines in the far infrared part of the spectrum, as observed in the redshifted signals from distant star forming galaxies. ZEUS-2 itself is equipped with two NIST TES bolometer arrays, one of which is tuned to 400 microns, while the other contains two further sub-arrays at 215 and 645 microns. When observing point sources, optical bandpass filters allow ZEUS-2 to address either of two pairs of telluric windows, 200 and 650 microns or 350 and 450 microns. But when looking at larger objects, all four telluric windows can be observed simultaneously, courtesy of the optical bandpass filters placed directly over the ZEUS-2 detector.
Real World Applications
This latest experiment was an attempt to improve the performance of the detector at 350 and 450 microns, where results have proven to be background-limited in the past. However, ZEUS-2 has already been deployed four times on real-world projects, where it was used in observations made using the APEX telescope in Chile. Dahlin’s poster details the work done during the summer of 2016 to further fine tune the performance of the spectrometer, and is among those exhibited at the 229th AAS Meeting in Grapevine, Texas on January 3rd-7th.