NIRCam Apertures

JWST NIRCam apertures define target reference positions and nominal extent in the field of view for all observations.

Apertures define targetable areas and their extents in the JWST field of view. Each aperture has a reference position to coincide with the observed target as well as outer bounding coordinates defining the nominal coverage of each observation. These definitions are stored in the Science Instrument Aperture File (SIAF).

Simplified entries are given below for several apertures, not including most subarrays. These provide locations and extents of all 10 NIRCam detectors as well as the field of view for each coronagraphic occulting mask.  (The coronagraphic field of view is projected onto the detectors when in use.)

The ALL1 aperture is used for full frame observations with both modules. It defines the full extent displayed in APT Aladin as well as the default size for each tile in a mosaic. Full frame observations with module B alone use the "Bs" aperture. "Bs" spans the full extent of the short wavelength detectors in module B.

The aperture coordinates may change slightly based on calibration measurements obtained in flight.

All NIRCam apertures are nearly aligned (to ~1° of rotation) with both the JWST coordinate system (V2, V3) and all detector rows and columns.

Figure 1. Prominent NIRCam apertures

Prominent NIRCam apertures

Target reference positions ("X") and and aperture vertices (outlines) for the NIRCam detectors and coronagraphic masks in JWST (V2, V3) coordinates. Each detector is labeled (A1–B5). Blue and red correspond to the short and long wavelength channels, respectively. The smaller squares at the top are coronagraphic apertures with mask names labeled below. The larger ALL and Bs apertures are drawn in black dashed and gray dotted lines, respectively. Coordinates for all of these apertures are given in the tables below.

Table 1. NIRCam apertures for all ten detectors in (V2, V3) arcseconds

SCAV2_RefV3_RefV2_1V2_2V2_3V2_4V3_1V3_2V3_3V3_4
A1120.67-527.3988.90153.16152.0888.69-559.88-559.27-495.15-495.59
A2120.11-459.68151.3888.6888.56151.95-427.95-428.17-491.49-491.11
A351.93-527.8019.4984.0583.8320.15-560.22-560.03-495.73-495.59
A452.28-459.8183.7120.8020.3984.00-428.20-428.00-491.59-491.46
A586.10-493.2320.88151.45149.7322.23-558.60-557.79-428.63-428.46
B1-120.97-457.75-89.52-152.07-152.82-89.59-426.35-426.00-489.07-489.58
B2-121.14-525.46-153.74-89.55-89.05-152.37-557.14-558.09-493.86-493.08
B3-53.12-457.78-21.93-84.75-84.57-21.05-425.81-426.40-489.59-489.32
B4-52.82-525.73-84.82-20.32-21.16-84.77-557.99-558.08-493.47-493.71
B5-89.39-491.44-25.54-153.25-154.75-23.98-426.52-426.75-556.16-556.87
ALL-0.32-492.59153.16-153.74-152.07153.16-559.27-557.14-426.00-427.95
Bs-82.29-496.21-20.32-153.74-152.07-21.93-558.08-557.14-426.00-425.81

Scroll right to view the full table.

Table 1 shows the target reference positions ("Ref") and aperture vertices (1–4) for the NIRCam detectors (SCAs) in JWST (V2, V3) coordinates in arcseconds. The penultimate row marked "ALL" is invoked when observing with both modules and defines the nominal tile spacing for mosaics. The final row "Bs" is used for full frame observations with module B alone. 


Table 2. NIRCam apertures for coronagraphic occulting masks in (V2, V3) arcseconds

MaskV2_RefV3_RefV2_1V2_2V2_3V2_4V3_1V3_2V3_3V3_4
A2_210R127.23-405.24137.11117.44117.39137.00-415.05-415.17-395.46-395.36
A5_335R107.51-405.52117.5697.5997.55117.47-415.45-415.55-395.51-395.43
A5_430R87.25-405.1997.2777.2977.3297.24-415.17-415.19-395.13-395.13
A4_SWB67.61-404.6777.4657.7557.7677.40-414.53-414.57-394.82-394.81
A5_LWB47.21-404.4457.2137.1437.2957.30-414.52-414.40-394.27-394.43
B1_210R-127.15-401.74-117.43-137.05-136.89-117.33-411.67-411.51-391.85-392.00
B5_335R-107.44-402.03-97.48-117.49-117.44-97.50-412.13-412.06-392.00-392.06
B5_430R-87.21-402.19-77.21-97.23-97.25-77.29-412.26-412.26-392.18-392.16
B3_SWB-47.27-401.91-37.33-57.05-57.21-37.55-411.72-411.87-392.15-391.96
B5_LWB-67.27-402.33-57.22-77.27-77.35-57.36-412.38-412.45-392.35-392.24

Scroll right to view the full table. 


Table 2 shows the nominal target reference positions ("Ref") and aperture vertices (1–4) for the coronagraphic occulting masks in JWST (V2, V3) coordinates in arcseconds. Bar occulters (with names ending in "B") have multiple reference positions (not shown here), one for each allowed filter. Note that module A will be used for coronagraphy; module B masks are shown for completeness.

1  Bold italics font style is used to indicate parameters, parameter values, and/or special requirements that are set in the APT GUI.




Published

 

Latest updates

  • corrected aperture B3 vertex coordinates V2_1, V2_2, V2_3, V2_4