RAW mode observations

RAW mode observations are less efficient than ADD mode (see tables below).

Imaging

All on-chip chopping.
Filter RAW mode
N8.8
UIR8.6
UIR11.2
43%
N9.7 N/A
N10.5
N11.7
N12.4
Q24.5
33%
ArIII 59%
SIV 63%
NeII 61%
Q17.7
Q18.8
Q20.5
N/A

†: RAW mode is not available for these filters.
‡: ADD and RAW modes for the ArIII filter produce exactly the same results (i.e., no gain of any kind by switchinng to RAW mode).

Spectroscopy

Chopping along the slit (i.e., both positive and negative beams on the slit).
Grating Efficiency
NL 57%
NM FULL 69%*
NH 85%*
QM FULL 69%

*: ADD and RAW modes for NM FULL and NH produce exactly the same results (i.e., no gain of any kind by switchinng to RAW mode).


We have found a serious flaw in the calculation of the observing efficiency of RAW mode published in 2011 August. We have now corrected these numbers above.

We sincerely apologise for those who considered using RAW mode but abandoned the idea upon seeing the erroneously calculated extremely low efficiencies between 2011 August and 2014 October.

Takuya Fujiyoshi
2014/10/08



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