Integration Time Calculator
Heterodyne receivers	APEX 1 [211-270 GHz] APEX 2 [265-370 GHz] APEX 3 [375-500 GHz] APEX T2 [1250-1384 GHz] FLASH 460 [430-492 GHz] FLASH 810 [780-887 GHz] APEX 2A [279-381 GHz]	By entering the atmospheric temperature (some 10 degrees below the ground temperature at Chajnantor), the (average) elevation of the source, the receiver temperature, required σ (in K), and the spectral resolution, the on-source integration time can be estimated. Also the total time is calculated assuming toff=ton and a system observing efficiency of 0.625, i.e. ttotal=(ton + toff)/0.625. The system efficiency takes into account time for telescope movements and calibrations.
Frequency [GHz]
Trec [K]
PWV [mm H2O]
Tatm [K]
Zenith opt depth
Source elevation [deg]
RMS [K]
FFTS [Number of channels]	1024 2048 4096 8192
Vel. resolution Δv [km/s]
Tsys [K]
Position switching on-time		Total PSW time [s]
Beam switching on-time		Total BSW time [s]

RMS Calculator
Heterodyne receivers	APEX 1 [211-270 GHz] APEX 2 [265-370 GHz] APEX 3 [375-500 GHz] APEX T2 [1250-1384 GHz] FLASH 460 [430-492 GHz] FLASH 810 [780-887 GHz] APEX 2A [279-381 GHz]	By entering the atmospheric temperature (some 10 degrees below the ground temperature at Chajnantor),the (average) elevation of the source, the receiver temperature, an on-source integration time ,and the spectral resolution, the σ (in K) can be estimated.See the observing time calculation page for details. To use a coarser vel. resolution Δvnew than selectable multiply the resulting σ with sqrt(Δv/Δvnew).
Frequency [GHz]
Trec[K]
PWV [mm H2O]
Tatm [K]
Zenith opt depth
Source elevation [deg]
tint ON [sec]
FFTS [Number of channels]	1024 2048 4096 8192
Vel. resolution Δv [km/s]
Tsys [K]
Position switching σ [K]
Beam switching σ [K]