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#author("2022-12-25T17:19:29+00:00","default:mimizuku","mimizuku") #author("2022-12-25T17:25:27+00:00","default:mimizuku","mimizuku") [[Observing]] *Available Filters [#f0f8178f] Available filters are shown in the table below. |Name|Center wavelength &br; (um)|Band width&br;(FWHM; um)|Note|h |32um|31.76|2.38|| |37um|37.43|2.96|| *Saturation limit [#x19a491a] Saturation limits are calculated as shown in the Table below. The limits are highly dependent on PWV. However, since the atmospheric transmittance is not good, the limits are very high, and we do not need to care about saturation basically. |Name|Saturation limit|h |32um|>28 kJy| |37um|>100 kJy| *Sensitivity [#u0206e70] Noise-equivalent flux density for one exposure is calculated as shown in the figures 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>Seeing Condition]]). Since readout noise (assumed 4000e-/read) is the main noise source in short exposures, sensitivity improves with longer exposure times. In the bands at 7.7 um and in the Q band, significant PWV dependency is confirmed. The truncation in the right edge of each band shows the longest exposure time. For accurate subtraction of background emission, it may be better to limit the exposure time for one exposure to less than 0.20 sec. Noise-equivalent flux density for one exposure is calculated as shown in the figures 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>Seeing Condition]]). Since the background emission is high, the noise is limited by the photon noise of the background emission, and the sensitivity is almost independent of exposure time. On the other hand, it is significantly affected by PWV, because the atmospheric transmittance highly varies with PWV. The truncation in the right edge of each band shows the longest exposure time. For achieving the shortest exposure shown in the figure below, partial readout is needed. |LEFT:100|LEFT:100|c |&ref(sensitivity_dia_nband.jpg,,30%);|&ref(sensitivity_dia_qband.jpg,,30%);| |Noise equivalent flux density for one exposure in the N band. Corresponding 1-sigma 1-sec sensitivity is shown by dotted lines. Multiple lines for each filter set show different PWV conditions (from bottom to top, 0.3, 0.5, 0.7, 0.9, 1.2, and 1.5 mm).|Same as the left figure, but for the Q band.| |LEFT:100|c |&ref(sensitivity_dia_30um.jpg,,30%);| |Noise equivalent flux density for one exposure in the N band. Corresponding 1-sigma 1-sec sensitivity is shown by dotted lines. Multiple lines for each filter set show different PWV conditions (from bottom to top, 0.3, 0.5, 0.7, 0.9, 1.2, and 1.5 mm).|
