pixlimit Are both sensors cooled at the same time?
Most likely, there is a single Peltier device -- a rectangle with one surface touching a sensor and the other surface touching a heat sink to dissipate the heat. One surface cools while the other surface is heated. That device will most likely only be large enough to cover the size of the main sensor. The fact that the two sensors don't have the same distance to the substrate (for focusing) also makes it difficult to make a single Peltier device work for both sensors simultaneously.
Equally likely, because of the heat generated by the main camera's Peltier device, the small uncooled sensor could be operating at an elevated temperature compared to the temperature of a stand-alone guide sensor in its own camera chamber (cooled by ambient temperature instead of the elevated temperature in the dual camera chamber).
Unless there is an extra Peltier device added to the guide chip, it is likely that not only is the guide sensor not cooled, it icould be running hotter than a typical guide camera.
ZWO should have all this data during their engineering validation tests.
Chen
