Mar 28 2026 APP 2.0.0-beta40 will be released in 7 days.
It did take a long time to have the work finished on this and it will have a major performance boost of 30-50% over 2.0.0-beta39 from calibration to integration. We extensively optimized many critical parts of APP. All has been tested to guarantee correct optimizations. Drizzle and image resampling is much faster for instance, those modules have been completely rewritten. Much less memory usage. LNC 2.0 will be released which works much better and faster than LNC in it's current state. And more, all will be added to the release notes in the coming weeks...
Update on the 2.0.0 release & the full manual
We are getting close to the 2.0.0 stable release and the full manual. The manual will soon become available on the website and also in PDF format. Both versions will be identical and once released, will start to follow the APP release cycle and thus will stay up-to-date to the latest APP version.
Once 2.0.0 is released, the price for APP will increase. Owner's license holders will not need to pay an upgrade fee to use 2.0.0, neither do Renter's license holders.
The bias pedestal is an ADU (Analog Digital Unit) offset in your data. This pedestal is always there, in your light, flat, dark and bias frames. So the ADU values up until this offset value is always there and it actually is not real data. All ADU values above the bias pedestal are real data, but should be interpreted as the ADU value minus the Bias pedestal.
Let's look at a master bias frame of a zwo optical asi1600mm-cool camera and it's histogram:
 The histogram shows you the value of the bias pedestal. It's almost exactly located at the peak of the histogram. Try to know this value for your camera's sensor with the ISO/gain and /or offset that you are shooting with.
- For DSLR camera's this value normally is the same for all ISO settings.
- For users of astronomical CCD/CMOS camera's, the bias pedestal corresponds to the offset and, usually, can be set manually depending on the camera's manufacturer.
In the FITS header of the master bias, created by APP, you'll find the ADU value of the bias pedestal, in this case we see:
HDU1 - CALFRAME= 'master bias'       / master bias frame                            Â
HDU1 - INSTRUME= 'ASI Camera (1)'    / instrument name                              Â
HDU1 - CFAIMAGE= 'no     '          / Color Filter Array pattern                   Â
HDU1 - MEAN   = ' 1,53E+02'         / mean of channel                              Â
HDU1 - MED    = ' 1,53E+02'         / median of channel                            Â
HDU1 - SIGMA  = ' 3,12E+00'         / standard deviation of channel                Â
HDU1 - NOISE  = ' 2,93E+00'         / MRS gaussian noise estimate of channel   Â
The median/mean values indicate it: 1,53E+02, which is a scientific notation for 153 ADUs.
To come back to:
 "So the ADU values up until this offset value is always there and it actually is not real data."
This is the fundamental reason, why this bias pedestal is so important to understand.
In light frame calibration this bias pedestal must be subtracted by either
- a Master Bias of the same ISO or gain + offset
- A Master Darks of the same ISO or gain + offset.
- Or a Master Dark of MasterBias subtracted darks + a Master Bias. both of the same ISO or gain + offset.
APP, currently, will not allow the use of a MasterBias shot with a different ISO or gain+offset than the ISO or gain+offset of your lights, since this will lead to suboptimal calibration for the read noise patterns of your sensor.
For flat frame calibration the same holds, flats need to be calibrated using:
- a Master Bias of the same ISO or gain + offset
- A Master Dark of the same ISO or gain + offset.
- Or a Master Dark of MasterBias subtracted darks + a Master Bias, both of the same ISO or gain + offset.
