NIRCam Filters

JWST NIRCam offers 29 bandpass filters in the short wavelength (0.6–2.3 μm) and long wavelength (2.4–5.0 μm) channels.

On this page

Each of the two NIRCam modules carries a nearly identical set of 29 filters. Most filters are located in the filter wheel and are used in combination with pupil wheel elements including CLEAR, grism, coronagraph Lyot stops, and weak lenses.

The six filters located in the pupil wheels (F162M, F164N, F323N, F405N, F466N, and F470N) include their individual pupil aperture stops and are used in combination with a second filter in the filter wheel (F150W2, F322W2, or F444W) because the filter wheels contain no CLEAR elements.

 


Filter transmissions

Filter transmissions (including all system throughputs) are plotted in Figures 1 and 2; ASCII tables are also provided.

Throughputs vary somewhat between the two modules, especially at long wavelengths due to differences in detector quantum efficiencies. Total throughputs are shown in Figures 1 and 2 for each module, individually and averaged between modules.


Table 1.  Numbers of extra-wide, wide, medium, and narrow filters in each wavelength channel

FiltersR = λ/Δλ

Short wavelength channel
(0.6–2.3 μm)
Number of filters

Long wavelength channel
(2.4–5.0 μm)
Number of filters

All~1–921316
Extra-wide~1–211
Wide~4–553
Medium~82048
Narrow~78–9234

Figure 1. NIRCam + JWST Optical Telescope Element (OTE) filter throughputs
Preliminary total system throughput for each NIRCam filter, including contributions from the JWST Optical Telescope Element (OTE), NIRCam optical train, dichroics, filters, and detector quantum efficiency (QE). Throughput refers to photon-to-electron conversion efficiency. Averages of NIRCam modules A and B transmissions are plotted. At the longest wavelengths, there are notable differences between the two modules' detector QE and filter transmissions. The vertical gray bar marks the approximate dichroic cutoff between the short and long wavelength channels. Filters marked "P" are located in the pupil wheel, requiring transmission through a second filter in the filter wheel, either F150W2, F322W2, or F444W. In these cases, the combined transmissions are plotted. (Figure version 4.0: April 22, 2016)
Figure 2. NIRCam filter throughputs in both modules

NIRCam filter throughputs in both modules

System throughput for each of the NIRCam filters shown in Figure 1 (with the same colors). Plots with a black outline correspond to module A, while the gray outline shows module B. The most significant differences between modules are at the longest wavelengths where module B offers higher throughput. (Version 4.0 data)


Filter lists

Download all filter transmission curves (version 4.0: April 2016): (tar.gz) (zip)

The filter transmission curves archive file contains:

  • both data (ASCII) and plots (PDF);
  • data for each individual module as well as averages of both modules;
  • filter only, NIRCam only, and the total system throughput data;
  • measured/expected transmissions for the filters, dichroic, optics, and the JWST OTE;
  • detector quantum efficiencies (QE).

Module-averaged total system transmission curves for all filters are available via the links in column 1 of Tables 2 and 3.


Tables 2 and 3. Characteristics of filters in the short and long wavelength channels

Short wavelength channel (0.6–2.3 µm)

Filter
(module-
average)
Pivot1
λ (µm)
BW2
Δλ (µm)
Effective3
response
Blue4
λ-
(µm)
Red4
λ+
(µm)
Use
F070W0.7040.1320.2000.6210.781General purpose
F090W0.9020.1940.2920.7951.005General purpose
F115W1.1540.2250.3251.0131.282General purpose
F140M1.4050.1420.3971.3311.479Cool stars, H2O, CH4
F150W1.5010.3180.4221.3311.668General purpose
F162M1.6270.1680.4161.5421.713Cool Stars, off-band for H2O
F164N1.6450.0200.3551.6351.653[FeII]
F150W21.6591.1750.4151.0082.334Blocking filter for F162M, F164N, and DHS
F182M1.8450.2370.4541.7221.968Cool stars, H2O, CH4
F187N1.8740.0240.3741.8631.884Pa-alpha
F200W1.9890.4570.4721.7552.226General purpose
F210M2.0950.2060.4611.9922.201H2O, CH4
F212N2.1210.0270.3942.1092.134H2


Long wavelength channel (2.4–5.0 µm)

Filter
(module-
average)
Pivot1
λ (µm)
BW2
Δλ (µm)
Effective3
response
Blue4
λ-
(µm)
Red4
λ+
(µm)
Use
F250M2.5030.1800.3832.4122.595CH4, continuum
F277W2.7620.6830.3892.4163.127General purpose
F300M2.9890.3150.3632.8293.155Water ice
F322W23.2321.3560.4432.4304.013Background min. Primarily used w/ grisms. Blocking filter for F323N.
F323N3.2370.0380.2853.2173.255H2
F335M3.3620.3520.4173.1773.538PAH, CH4
F360M3.6240.3700.4583.4273.814Brown dwarfs, planets, continuum
F356W3.5680.7810.4803.1403.980General purpose
F405N4.0520.0450.3724.0284.074Br-alpha
F410M4.0820.4380.4693.8644.301Brown dwarfs, planets, H2O, CH4
F430M4.2810.2280.4694.1674.398CO2, N2
F444W4.4081.0290.4743.8804.986General purpose. Blocking filter for F405N, F466N, F470N.
F460M4.6300.2290.3924.5154.747CO
F466N4.6540.0540.2934.6294.681CO
F470N4.7080.0510.2744.6834.733H2
F480M4.8740.3000.3174.6624.977Brown dwarfs, planets, continuum


Table notes:

  1. The pivot wavelength satisfies the equation F_\lambda \lambda_{pivot}^2 = F_\nu c, relating the flux measured in wavelength versus frequency units (F_\lambda d \lambda = F_\nu d \nu). It is calculated as \lambda_{pivot} = \sqrt{\frac{\int d\lambda T \lambda}{\int d\lambda T / \lambda}}, where T is the transmission. See Tokunaga & Vacca 2005.  

  2. Bandwidth is the integral of the normalized transmission curve: BW = \frac{\int d\lambda T}{T_{max}}. See equation 1 in appendix E of Rieke, G. H. et al. 2008

  3. Effective response is the mean transmission value over the wavelength range of \lambda_{pivot} \pm BW ~ / ~ 2.

  4. The half power wavelengths of a passband are the wavelengths at which the transmission falls to 50% of its peak value.



References

Rieke, G. H., Blaylock, M., Decin, L., et al. 2008, AJ, 135, 2245
Absolute Physical Calibration in the Infrared

Tokunaga, A. T., & Vacca, W. D., 2005 PASP 117, 421
The Mauna Kea Observatories Near-Infrared Filter Set. III. Isophotal Wavelengths and Absolute Calibration




Published

 

Latest updates