NIRCam Design Features and Performance

The parameters presented here largely "as built" values. Small changes may still result from updates on the telescope performance.  Sensitivity and saturation limits are given below. Filter details are available below.

 

The key design features are:

  • Nyquist-sampled imaging at 2 and 4 microns -- short wavelength sampling is 0.0317"/pixel and long wavelength sampling is 0.0648"/pixel
  • 2.2'x4.4' FOV for one wavelength provided by two identical imaging modules, two wavelengths observable simultaneously via dichroics
  • Wavelength coverage from 0.6 to 5 microns
  • Selection of broad, intermediate, and narrow band filters (see chart below)
  • Choice of pupil positions for imaging, coronagraphy or wavefront sensing
  • All NIRCam modules have coronagraphic spots in the telescope focal plane. The pupil wheels include coronagraphic masks.
  • R~1700 grisms in the LW arms (two per module oriented at 90° relative to each other).  Approximate dispersion is 0.00100 microns/pixel.  Grisms need to be used in series with a bandpass filter in the filter wheel.
Layout

 

NIRCam will have the sensitivity to detect first light sources and a whole lot more as shown in the listing of sensitivities by filter. Note that these values are for point sources observed against 1.2 times the minimum zodaical background.

H2RGNIRCam uses 2Kx2K HgCdTe focal planes from Teledyne Imaging Sensors.

Module B SW coronagraphic masks

Images of the Module B Coronagraphic Mask taken through the SW arm.

makss

Schmatic layout of the coronagrphic mask (reversed from actual image).

 

Sample Grism Data from ISIM-Level Testing at Goddard -- a carbon dioxide ice feature from the telescope simulator is apparent.

Grism

 

Estimated NIRCam Point Source Sensitivities Observing against 1.2x Zodiacal Min Background

First table gives sensitivity in 10000 sec which is comprised of 10 1000 sec exposures. Tables below this one give sensititivies for times between 10.7 sec and 1000 sec. For 1000 < time < 10000 secs, correct the 10000 sec value by SQRT(10000/time)

Filter 10-s in 10000 sec (nJy )
F070W 22.5
F090W 15.3
F115W 13.2
F150W 10.6
F200W 9.1
F277W 14.3
F322W2 9.1
F356W 12.1
F444W 23.6
F140M 19.4
F162M 21.4
F182M 16.1
F210M 14.9
F250M 32.1
F300M 25.8
F335M 21.8
F360M 20.7
F410M 24.7
F430M 50.9
F460M 46.5
F480M 67.9
F164N 145
F187N 133
F212N 129
F323N 194
F405N 158
F466N 274
F470N 302

These tables give sensitivites as 10-sigma in nJy for times < 1000 sec.

Wide Filters

Time (secs)
F070W
F090W
F115W
F150W
F200W
F277W
F322W2
F356W
F444W
10.7
10049
6174
5422
4172
3528
2846
1386
2666
3398
96.7
930
575
504
389
329
326
168
300
419
204
344
216
189
147
125
138
78
123
198
311
210
134
117
92
78
95
57
83
145
419
153
99
86
68
58
76
47
66
120
526
123
81
70
56
47
66
41
56
105
634
104
69
60
48
41
58
36
50
94
741
92
62
53
43
36
53
33
45
86
848
83
56
49
39
33
49
31
42
80
956
76
52
45
36
30
46
29
39
75

Medium Filters

Time (secs)
F140M
F162M
F182M
F210M
F250M
F300M
F335M
F360M
F410M
10.7
10368
12324
8469
7938
10070
8000
6888
6652
6603
96.7
951
1127
777
728
1091
868
746
720
726
204
344
405
282
264
405
323
277
266
280
311
205
238
168
157
255
204
174
167
183
419
145
167
119
111
194
155
132
126
142
526
114
130
94
87
160
129
109
104
119
634
95
108
79
73
139
112
95
90
105
741
83
93
69
64
124
100
84
81
94
848
74
83
61
57
113
91
77
74
87
956
67
75
56
52
105
84
71
68
80
Time (secs)
F430M
F460M
F480M
10.7
16021
9072
12965
96.7
1735
1042
1495
204
643
442
637
311
405
307
444
419
307
247
359
526
254
213
309
634
220
189
276
741
197
173
251
848
180
160
233
956
166
149
217

Narrow Filters -- these values are 10-sigmas in microJy

Time (secs)
F164N
F187N
F212N
F323N
F405N
F466N
F470N
10.7
119
114
106
99
77
118
129
96.7
10.8
10.4
9.66
10.4
8.16
12.5
13.8
204
3.78
3.63
3.38
3.58
2.81
4.38
4.81
311
2.15
2.07
1.93
2.07
1.64
2.60
2.85
419
1.45
1.39
1.30
1.46
1.16
1.87
2.06
526
1.08
1.04
0.97
1.14
0.91
1.49
1.64
634
0.86
0.83
0.78
0.94
0.76
1.26
1.38
741
0.72
0.69
0.65
0.81
0.65
1.10
1.21
848
0.62
0.60
0.56
0.72
0.58
0.99
1.09
956
0.54
0.52
0.49
0.65
0.53
0.90
0.99

 

NIRCam DHS + Grism Saturation Limits for 2048x64 Pixel Stripe Using Reset-Read-Read Mode -- blue is DHS + F150W2, red is F322W2+Grism, and green is F444W+Grism

plot of saturation limits

Table gives the K-mag (Vega) of a star that reaches ~80% full well inthe mode indicated for the filter assuming G2V.Reset-read-read is assumed.

Imaging
Full Frame
160x160
32x32
Stripe Mode 2048x32
Stripe Mode 2048x16 
F070W
14.81
10.76
7.26
10.27
9.52
F090W
15.35
11.29
7.79
10.81
10.05
F115W
15.47
11.41
7.92
10.93
10.17
F140M 14.81 10.75 7.26 10.27 9.52
F150W
15.63
11.57
8.08
11.09
10.33
F150W2
17.01
12.95
9.45
12.46
11.71
F162M 14.65 10.59 7.10 10.11 9.36
F164N 12.08 8.02 4.53 7.54 6.79
F182M 14.78 10.72 7.23 10.24 9.49
F187N 11.50 7.44 3.95 6.96 6.21
F200W
15.11
11.06
7.56
10.57
9.82
F210M
14.21
10.15
6.66
9.67
8.91
F212N
11.44
7.39
3.89
6.90
6.15
F250M
14.50
10.45
6.95
9.96
9.21
F277W
15.48
11.43
7.93
10.94
10.19
F300M
14.22
10.16
6.66
9.67
8.92
F322W2
15.80
11.74
8.25
11.26
10.51
F323N 
11.13
7.08
3.58
6.59
5.84
F335M
13.92
9.87
6.37
9.38
8.63
F356W
14.76
10.70
7.21
10.22
9.47
F360M
13.72
9.67
6.17
9.18
8.43
F405N 
10.62
6.56
3.07
6.08
5.33
F410M
13.17
9.12
5.62
8.63
7.88
F430M
12.20
8.14
4.65
7.66
6.90
F444W
13.82
9.76
6.26
9.27
8.52
F460M
11.80
7.74
4.25
7.26
6.51
F466N 
9.58
5.52
2.03
5.04
4.28
F470N 
9.69
5.64
2.14
5.15
4.40
F480M
12.00
7.95
4.45
7.46
6.71
                        NIRCam Filters   

                                   Wavelengths in microns

Name Center lambda 1 lambda 2 Bandpass Location %T Use
F070W 0.6950 0.6103 0.7797

0.1695

SW-Filt 0.910 General purpose
F090W 0.8989 0.7931 1.0046

0.2115

SW-Filt 0.948 General purpose
F115W 1.1457 1.0102 1.2812

0.2709

SW-Filt 0.864 General purpose
F150W 1.5002 1.3313 1.6690

0.3377

SW-Filt 0.941 General purpose
F150W2 1.5000 1.0000 2.0000

1.0000

SW-Filt ~0.8 DHS Blocking
F200W 1.9909 1.7544 2.2274

0.473

SW-Filt 0.969 General purpose
F277W 2.7834 2.4311 3.1356

0.7045

LW-Filt 0.900 General purpose
F322W2 3.2262 2.4342 4.0182 1.5840 LW-Filt 0.908 Background Min.
F356W 3.5544 3.1379 3.9709

0.8331

LW-Filt 0.945 General purpose
F444W 4.4343 3.8833 4.9943

1.1199

LW-Filt 0.901 General purpose
F140M 1.4040 1.3300 1.4787

0.1486

SW-Filt 0.941 cool stars, steam
F162M 1.6268 1.5415 1.7121

0.1706

SW-Pup 0.972* cool stars, off-band for steam
F182M 1.8436 1.7214 1.9657

0.2442

SW-Filt 0.966 cool stars, steam
F210M 2.0937 1.9906 2.1968

0.2062

SW-Filt 0.965 methane
F250M 2.5035 2.4123 2.5946

0.1823

LW-Filt 0.868 methane
F300M 2.9927 2.8312 3.1542

0.3230

LW-Filt 0.905 water ice
F335M 3.3585 3.1828 3.5343 0.3515 LW-Filt 0.900 PAH
F360M 3.6170 3.4238 3.8102 0.3864 LW-Filt 0.879 Brown dwarfs,planets
F410M 4.0918 3.8782 4.3054

0.4272

LW-Filt 0.881 Brown dwarfs,planets
F430M 4.2816 4.1645 4.3986

0.2342

LW-Filt 0.861 carbon dioxide
F460M 4.6272 4.5113 4.7432

0.2319

LW-Filt 0.762 CO
F480M 4.8024 4.6564 4.9484

0.2921

LW-Filt 0.778 Brown dwarfs,planets
F164N 1.6442 1.6352 1.6531 0.0179 SW-Pup 0.809* [FeII]
F187N 1.8747 1.8642 1.8852

0.0210

SW-Filt 0.802 P-alpha
F212N 2.1209 2.1102 2.1315

0.0213

SW-Filt 0.804 Molecular hydrogen
F323N 3.2361 3.2167 3.2556

0.0390

LW-Pup 0.709* Molecular hydrogen
F405N 4.0503 4.0279 4.0728

0.0449

LW-Pup 0.744* Br-alpha
F466N 4.6548 4.6290

4.6805

0.0516

LW-Pup 0.688* CO
F470N 4.7080 4.6838 4.7321 0.0483 LW-Pup 0.646* Molecular hydrogen

* Filter must be used in series with another filter; transmission is for this filter only.

 

 

Correspondence Between Filters and Common Solid FeaturesIces

 
Wheel layout  

Graphical depiction of NIRCam filters. The vertical bar indicates the beamsplitter deadband while P indicates those filters in the pupil wheels.

Filter Schematic