nir_spectroscopy_20230101(No. 1)

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  • 1 (2022-12-31 (Sat) 15:36:53)
  • 2 (2023-01-01 (Sun) 00:58:09)

Observing

Available Modes†

Available spectroscopic modes are listed in the table below. To avoid saturation due to the strong emission from the diamond window, an ND filter with OD=2 is needed for observations in the LM band.

Saturation limit†

Saturation limits depend on wavelength as shown in the figures below, and the typical levels are summarized in the table below.

Sensitivity†

Noise-equivalent flux density for one exposure is calculated as shown in the figure below. Corresponding 1-sigma 1-sec sensitivity is also plotted. This calculation assumes aperture photometry with an aperture diameter of 2.5 times the FWHM of the PSF in the medium seeing condition (see here). Since readout noise (assumed 100e-/read) is the main noise source in short exposures, sensitivity improves with longer exposure times. PWV dependency is not significant in these bands. The truncation in the right edge of each band shows the longest exposure time before saturation except for the J band. The sensitivities of the L' and M' bands are significantly worse due to the ND filters and the strong absorption of the diamond window.