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== Information for Observers on NIKA2 Bandpasses ==
=== Bandpasses of the NIKA2 Arrays ===

==== after 3/2025 ====

In March 2025, NIKA2 was upgraded. New 1mm KID arrays were installed, the dichroic was exchanged, various filters have been exchanged. New measurements of the in-situ bandpasses were conducted with the Martin-Puplett interferometer "PIMP". These new 1mm bandpasses are shown below and included in the following ASCII table, together with three atmospheric transmission curves for 2mm, 4mm, and 7mm of precipitable water vapour: [[attachment:nika2-bandpasses-atmMarch2025-4.dat]]. The 2mm bandpass is unchanged and given below.

{{attachment:nika2-bandpassesMarch2025-4.png}}

==== till 3/2025 ====

For convenience, we provide one ASCII file with the three NIKA2 bandpasses and three atmospheric transmission curves for 2mm, 4mm, and 7mm of precipitable water vapour: [[attachment:nika2-bandpasses-atm.dat]]. The instrumental bandpasses have already been corrected for the Rayleigh-Jeans source emission. They are shown in the figure below and also in Figure 1 of [[https://ui.adsabs.harvard.edu/abs/2020A%26A...637A..71P/abstract|Perotto et al. (2020)]]. These bandpasses were measured in the laboratory in Grenoble.

{{attachment:nika2-bandpasses3.png||height=550}} 

=== Atmospheric transmission curves ===

The ATM model of J.Pardo & P.Cernicharo was used to calculate the atmospheric transmission at Pico Veleta.  See also the figure below.

{{attachment:atmos-transmission9.png||height=550}}

=== Old information ===

The spectral bands as measured in Néel (note that the two 1.15mm arrays are pretty similar but there is a detectable difference):

{{attachment:xavier_v1.jpg||height=615}} 

{{attachment:xavier_v2.jpg||height=615}}