We have unfortunately found that overhead calculations in SPT v2_8_3 were incorrectly implemented for the HAWC+ "TOTAL_INTENSITY" configuration. If you are planning observations in that configuration, please calculate the overhead as outlined below, and enter the value into the "Alternate Overhead" box. (Note that the integration time and overheads have units of "seconds".)

If the "Integration Time" entered is "tint"

1. For C2N (NMC) mode: Alternate overhead = 300 + 8.9 * tint

2. For OTFMAP mode: Alternate overhead = 300 + 0.5 * tint

The default overhead for the "POLARIZATION" configuration (300 + 10.0 * tint) is correct.

Also, all calculations described in the HAWC+ chapter of the Observer's Handbook for Cycle 4 (in particular Figure 10-3) use the correct overhead values.