Use this calculator for on-off observations. If you are planning on-the-fly mapping, you should instead use the dedicated OTF calculator

Integration Time Calculator
Heterodyne receivers	APEX 1 [211-270 GHz] APEX 2 [267-375 GHz] APEX 3 [385-500 GHz] APEX T2 [1250-1384 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 0.4, i.e. ttotal=(ton + toff)/0.4.The system efficiency takes into account both system and setup+calibration overheads. System overheads include telescope movements, software overheads, observing mode efficiency, etc. Setup+calibration overheads include source acquisition, pointing, focus, receiver tuning and calibration scans.
Frequency [GHz]
Redshift Z
Sky 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 32768
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