Abstract
Context.Wide-field spectrometers are needed to deal with current astrophysical challenges that require multiband observations at millimeter wavelengths. An example of these is the KIDs Interferometer Spectrum Survey (KISS), which uses two arrays of kinetic inductance detectors (KIDs) coupled to a Martin-Puplett interferometer (MPI). KISS has a wide instantaneous field of view (1 deg in diameter) and a spectral resolution of up to 1.45 GHz in the 120–180 GHz electromagnetic band. The instrument is installed on the 2.25 m Q-U-I JOint TEnerife telescope at the Teide Observatory (Tenerife, Canary Islands), at an altitude of 2395 m above sea level.Aims.This work presents an original readout modulation method developed to improve the sky signal reconstruction accuracy for types of instruments for which a fast sampling frequency is required, both to remove atmospheric fluctuations and to perform full spectroscopic measurements on each sampled sky position.Methods.We first demonstrate the feasibility of this technique using simulations. We then apply such a scheme to on-sky calibration.Results.We show that the sky signal can be reconstructed to better than 0.5% for astrophysical sources, and to better than 2% for large background variations such as in “skydip”, in an ideal noiseless scenario. The readout modulation method is validated by observations on-sky during the KISS commissioning campaign.Conclusions.We conclude that accurate photometry can be obtained for future KID-based interferometry using the MPI.
Highlights
Forthcoming scientific challenges in millimeter astronomy require large-scale spectroscopic mapping of the sky both to discriminate among the different components of the sky signal and to achieve high sensitivity over large sky areas
A more suitable candidate for the observation of extended and diffuse sources is represented by Fourier transform spectroscopy (FTS), which permits a wide instantaneous field of view (FoV), exploiting a single large array for a wide range of frequencies
We use a high value of opacity of 0.15 at full bandwidth at the zenith, which represents the upper value exploited for real kinetic inductance detectors (KIDs) Interferometer Spectrum Survey (KISS) observations, in order to evaluate the goodness of the method in the worst background conditions
Summary
Forthcoming scientific challenges in millimeter (mm) astronomy require large-scale spectroscopic mapping of the sky both to discriminate among the different components of the sky signal and to achieve high sensitivity over large sky areas. The ground-based mm-wavelength experiments require the exploitation of low time-constant detectors, with high filling factor and fast interferometric pattern integration To meet this requirement, we have developed a spectrum imager named KISS (for the instrument description see Fasano et al 2020a,b), whose primary objective is to act as a technological test bed for the CONCERTO instrument. For previous KID experiments such as Néel IRAM KID Array (NIKA; (Monfardini et al 2010) and New IRAM KID Array 2 (NIKA2; (Adam et al 2018)), a two-sample modulation readout scheme was developed to obtain sufficient photometric accuracy (Calvo et al 2013) Such a scheme is not applicable for fast sampling rates such as those required for fast FTS imaging instruments such as KISS and CONCERTO.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
