370, CP, ZP vs extinction
ID: 370
Document: MICADO Calibration Plan
Location: 76, 6.1.2.3, 34
Reviewer: ASM
Submit: no
Responsible: JUP->HBU
Text:
It seems to me that we should distinguish between zeropoint (which, at the end, is more a chracteristic of the telescope+instrument system) and extinction (which is atmospheric). I would expect one extinction value but ZP for each detectors.
Answer:
We indeed plan to derive a single extinction value per exposure and and a zeropoint per detector per exposure. As a baseline we plan that each exposure will have a zeropoint derived with the atmospheric extinction computed simply from airmass plus fixed atmospheric extinction coefficient. If there are calibrators in the science image (e.g., Euclid and/or VISTA references) the zeropoint will be done on those. Otherwise the same procedure will be done on the nightly photometric reference field. We intend to offer in the interactive pipeline other ways to derive atmospheric extinction in case suitable input observations exist. For example same fields, observed at different airmasses. The detailed design for this will be made by end of Sep 2019.