Atacama Pathfinder EXperiment APEX
Heterodyne Instruments
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Observing time calculator

Please go to this page for the new observing time calculator: http://www.apex-telescope.org/heterodyne/calculator/ PWV [mm] [0.05,0.1....3] τzenith

RMS calculator
Integration time calculator
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. The APEX-2a receiver temperature is about 70 K for the entire tuning range.
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.

Tatm (K)
Source elevation (deg)
Trec (K)
tint ON (sec)
FFTS (Number of channels)
Frequency resolution (kHz)

Vel. resolution Δv (km/s)

τzenith
Frequency (GHz)
Tsys (K)
Position switching, σ (K)
Beam switching, σ (K)
Frequency switching, σ (K) (not implemented)

Tatm (K)  
Source elevation (deg)  
Trec (K)  
σ (K)  
FFTS (Number of channels)  
Frequency resolution (kHz)
 

Vel. resolution Δv (km/s)

 
τzenith  
Frequency (GHz)  
Tsys (K)  
Position switching ton ttotal
Beam switching ton ttotal
Frequency switching ton (not implemented) ttotal

 

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