News about chopping for SM & VM observers
Chopping with counter-chopping
Chopping (with counter chopping) is mandatory for M-band observations with NaCo in imaging mode.
For all other filters / mode, an autojitter pattern performs exactly as well.
Chopping with counter-chopping does work but under a number of restrictions, due to physical limitations of the system, and which are stated here.
- Chopping can only work on targets using a bright AO reference star, i.e. allowing the AO to correct at >= 50Hz.
Typically that would mean V <=15 or K <=10.
- The quality if the counter-chopping is at best when the
chop throw is <= 10".
Greater chop throw can be accepted if the idea is to have one of the beam out of the field of view.