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FLAMINGOS-2 contains Y, J, H, and Ks filters for imaging and spectroscopy. FLAMINGOS-2 also contains three additional custom filters for spectroscopy: a JH and an HK filter, for use with the JH and HK R~1300 grisms, and either of: a custom "J-low" filter, which has a centroid wavelength of 1.217 µm, or "K-long" filter, which has a centroid wavelength of 2.200 µm. J-low and K-long are meant to be used with the R3K (R ~ 3000) grism. The filters are located in two filter wheels: Filter Wheel #1 contains the K-long, J, H, and Ks filters, and Filter Wheel #2 contains the JH, HK, and Y filters, as well as a blank for dark frames. We also have two narrow band filters that will be installed at a later time. Further details can be found on the optomechanical diagrams.

The net system throughput curves (plots and data) for each filter (without the grisms) are linked from the table below. The net system throughput includes the transmission properties of the FLAMINGOS-2 optical train, including its window, its 9 lenses, and the reflectivity properties of its two flat mirrors. It does not include the effects of the atmosphere, the telescope, or the detector. Values for the centroid wavelength and equivalent width (EW) of the filter bandpass are given. The "cut-on" and "cut-off" wavelengths listed in the table are the wavelengths where the net transmission is higher than or equal to 80% or 50% (respectively) of the maximum transmission value.


Band Width


80% cut-on
80% cut-off
50% cut-on
50% cut-off
Y_G0811 1.020
89.4 0.985 1.066 0.969 1.068 plot/data
J_G0802 1.255
151 1.178 1.328 1.175 1.333 plot/data
H_G0803 1.631
274 1.490 1.767 1.486 1.775 plot/data
Ks_G0804 2.157
318 1.997 2.313 1.991 2.320 plot/data
Jlow_G0801(*) 1.122
132 1.056 1.189 1.048 1.192 plot/data
JH_G0809 1.390
720 1.163 1.774 0.970 1.805 plot/data
HK_G0806 1.871
1067 1.308 2.401 1.261 2.511 plot/data
K-long(**) 2.200 
600 1.906 
2.474 1.900 

(*)  Not available during 2015B-2016B.

(**) Available through 2016A. 


Transmission curves for the filters only, based on lab measurements, are also available.