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Zero Points

The following table lists zero points for NICI in several filters. A zero point is defined as the magnitude of an object that would yield 1 ADU/sec at an airmass of 1. They depend on instrument and telescope transmittances as well as detector electronics.

All values here were computed from observations of the near-infrared standard S372-S on 2008 Jan 31, with the H50/50 beamsplitter.

 

Filter Center wavelength (µm)

Zero point magnitude
(for 1 ADU/s)

(Holmes, red)

Zero point magnitude
(for 1 ADU/s)

(Watson, blue)

Sky background
(mag/arcsec)
CH4 H 4% S
1.578
  21.4
 
CH4 H 4% L
1.652
21.4
   
CH4 H 1% S
1.584
  19.7
 
CH4 H 1% L
1.627
20.0
   
J
1.27

22.0
 
H
1.65

23.5
 
Ks
2.17
23.1

 
Br-gamma
 2.1686
 19.9