SGP3.0.2.91 ZWO native driver e-gain not logged properly in FITS header


I tried using the ZWO native driver in SGP3.0.2.91, it allows the control of gain and offset, but the e-gain logged in the FITS header always give a value of 3.6.

Using the ASI generic ASCOM driver has the e-gain value logged according to the setting.

Also, it looks the CCD temperature is just logged with the ASI ASCOM driver.

Attached please find the 2 FITS files for reference, one captured with the ASI ASCOM driver with gain = 270, another one is with ZWO native driver with gain = 270.
2 files captured with ASI ASCOM and ZWO native driver


May I bring this up again for SGP support’s attention?

I contacted ZWO, and they mentioned the e-Gain logged in the FITS header is calculated in SGP when the native driver is used. While it is calculated in the ZWO ASCOM driver if the ASCOM driver is used.

Could SGP support take a look to improve the native driver e-Gain logging in the next release? I prefer to use the SGP native ZWO driver, as it allows the setting of offset by event, which is more flexible.

Thank you.


The native ZWO driver exposes eGain and we just store that in the FITs directly. If there is some calculations that need to occur in order to correct that I’m not sure what they are. I’ll reach out to ZWO and see what they say.



Hi Jared,

Just to bring up this topics again, as ZWO has it now in their SDK. They are contacting your developer on how to integrate it into SGP.