Because KPF contains many detectors, but they are all synchronized in time, the raw data is immediately combined in to a "Level 0" (L0) multi-extension FITS file by the kpfassemble dispatcher. Most users will want to use that L0 data for analysis or inspection.

Raw Data

Each detector writes data to a separate output directory and kpfassemble will collect them from these to generate the L0 file. This is a relatively quick process, typically the L0 file is written a few seconds after the component raw data are available on disk.

As mentioned on the detectors page, the Green and Red detectors have 32 bit ADCs and thus the pixel data do not fall on the usual 0-65535 range you may be used to.

L0 Data

The L0 data is a multi extension FITS file consisting of the following HDUs:

HDU #	HDU Name	Notes
0	PRIMARY	Header only, no image data
1	GREEN_AMP1	Green image data
2	GREEN_AMP2	Green image data
3	RED_AMP1	Red image data
4	RED_AMP2	Red image data
5	CA_HK	Ca H&K image data
6	EXPMETER_SCI	Table of processed exposure meter spectra
7	EXPMETER_SKY	Table of processed exposure meter spectra
8	GUIDER_AVG	The average guider image over the duration of the exposure
9	GUIDER_CUBE_ORIGINS	Table of telemetry from the tip tilt system
10	TELEMETRY	Table of instrument telemetry

This can change depending on the composition of the science observation. For example, if the Ca H&K detector was not triggered, that extension would not be used.