it is generally thought to be OK to calibrate flat subs with only bias frames as long as the flats are of short duration. the less dark current your camera's sensor has, the better in this regard. having said this, with an uncooled camera the dark current is going to be higher than with cooled sensors. still i see that your flats are 1.6-2s long and i'd imagine that calibrating the flats with only a bias frame should be OK.
calibration of bias frames is generally not necessary at all. i'd say this is a very specialized technique that only a few types of sensors would require. i think you might need to configure the overscan settings above the bias filename in order for bias calibration to even do anything. so i'm not surprised that nothing changed when you asked to calibrate the bias.
BPP's integration is considered to only be a preview because all of the pixel rejection stuff should be tuned to get a proper master light frame. for instance in theory you should integrate your master light with no pixel rejection and check the SNR, then set up a rejection method and adjust the rejection sliders before running again. you should then look at the rejection maps to make sure you don't see the structure of your object in the rejection maps, and you should test the new master light to make sure the SNR is still similar to the one made with no rejection.
i think BPP has always wanted dark frames and tries to scale them for calibration of the flats. there is a new checkbox in the "flats" section of BPP that tells BPP to look for shorter dark frames that match the flat duration and use those darks to calibrate the flats, instead of trying to scale (optimize) the darks or master dark that corresponds with the light duration. for you i guess you'd have to make darks of 1.6s and 2s and any other duration that your flats happen to be for this checkbox to work right.
the BPP script always creates calibrated master flats, so if you made a calibrated master flat by hand, you can just load that master flat and tick the "use master flat" checkbox. then load your lights and the darks that match the lights and run, and BPP should calibrate the lights using that master flat. this is a good way to do it with a DSLR for a couple of reasons - one is that sometimes people will use a different ISO for the flat and so you'd need a different ISO dark or bias to calibrate the flat and BPP doesn't really support different ISOs, so you need to present it with an already calibrated master flat. another reason is that if you do it this way you don't have to worry about making special darks for the flats nor do you have to worry about BPP matching them all up correctly. the only darks and bias it will care about when using a master flat are the ones that match the lights, so there is no confusion.
you can also do a "dummy" run of BPP with throwaway lights where the purpose is just to get BPP to build a properly calibrated master flat. if you wanted to calibrate the flat subs with bias only, you would do that by loading your bias frames as darks, load a few lights (maybe even just one would work, not sure) and then just run and save the master flat which is produced. then you reset BPP and load that master flat plus all your lights and darks and bias and run again, this time for real. and after that step you should then have a master dark and a master bias that you can load the next time around instead of the bias and dark subs.
rob
rob
