Space Telescope Science Institute   7.7.2 Ramp Filter Apertures  7.7.4 Polarizer Apertures

7.7.3 The Small Filter Apertures


When a filter designed for the HRC is used with the WFC, it only covers a small area on either WFC1 or WFC2. The projected filter position may be placed on either chip by selection of the filter wheel setting. Figure 7.4 shows how the filter projection may be placed so as to avoid the borders of the chips. When a WFC observation is proposed using a HRC filter spacecraft commanding software automatically uses internal built-in apertures designed for these observing scenarios, called WFC1-SMFL and WFC2-SMFL. Reference positions at or near the center of these apertures are defined so that a target may be placed in the region covered by the chosen filter.

The axis angles given in Table 7.6 do not refer to the edges of the apertures as drawn, but rather to the orientation of the x and y axes at the WFC reference pixel. These angles vary slightly with position due to geometric distortion.

For the polarizers and F892N used with WFC, the default will be to read out a subarray. The subarray will be a rectangular area with sides parallel to the detector edges which encompasses the indicated filtered areas. For ramp filters the default will be to readout the entire WFC detector, unless a polarizer is used with the ramp filter, in which case a subarray is readout. Users cannot override the small filter subarrays.

Table 7.6: WFC aperture parameters.
APT Aperture Name
Readout area
Extent
(arcsec)
Reference
pixel
Reference
V2,V3
(arcsec)
x-axis angle
y-axis angle
(degrees from V3 through V2)
WFC
4096 × 4096
202 × 202
(2124,200)
on WFC1
(262,239)
92.2
177.5
WFC-FIX
4096 × 4096
202 × 202
(2073,200)
(261,198)
92.5
177.3
WFCENTER
4096 × 4096
202 × 202
(2114,2029)
on WFC2
(261,252)
92.1
177.5
WFC1
4096 × 4096
202 × 202
(2124, 1024)
(263,198)
92.5
177.4
WFC1-FIX
4096 × 4096
202 × 202
(2072, 1024)
(261,198)
92.5
177.4
WFC2
4096 × 4096
202 × 202
(2124, 1024)
(259,302)
91.7
177.8
WFC2-FIX
4096 × 4096
202 × 202
(2072, 1024)
(257,302)
91.7
177.8
WFC1-IRAMP
4096 × 4096
25 × 65
(680,1325)
(194,187)
93.1
176.6
WFC1-MRAMP
4096 × 4096
35 × 80
(3096,1024)
(312,196)
92.2
177.8
WFC2-MRAMP
4096 × 4096
40 × 80
(1048,1024)
(206,304)
91.9
177.5
WFC2-ORAMP
4096 × 4096
35 × 65
(3494,708)
(328,316)
91.4
178.2
WFC1-SMFL 1
2048 × 2048
70 × 80
(3096,1024)
(312,196)
92.2
177.8
WFC2-SMFL 1
2048 × 2048
70 × 80
(1048,1024)
(206,304)
91.9
177.5
WFC1-POL0UV 2
2048 × 2048
90 × 80
(3096,1024)
(312,196)
92.1
177.8
WFC1-POL0V 2
2048 × 2048
90 × 80
(3096,1024)
(312,196)
92.2
177.8
WFC2-POL0UV 2
2048 × 2048
90 × 80
(1048,1024)
(206,304)
91.9
177.5
WFC2-POL0V 2
2048 × 2048
90 × 80
(1048,1024)
(206,304)
91.9
177.5
WFC1-512
512 × 512
25 × 25
(3864,1792)
(352,158)
92.1
178.0
WFC1-1K
1024 × 1024
50 × 50
(3608,1536)
(338,170)
92.1
177.9
WFC1-2K
2048 × 2048
101 × 101
(3096,1024)
(312,196)
92.2
177.8
WFC2-2K
2048 × 2048
101 × 101
(1048,1024)
(206,304)
91.9
177.5
WFC1-IRAMPQ
2048 × 2048
25 × 65
(680,1325)
(194,187)
93.1
176.6
WFC1-MRAMPQ
2048 × 2048
35 × 80
(3096,1024)
(312,196)
92.2
177.8
WFC2-MRAMPQ
2048 × 2048
40 × 80
(1048,1024)
(206,304)
91.9
177.5
WFC2-ORAMPQ
2048 × 2048
35 × 65
(3494,708)
(328,316)
91.4
178.2
WFC1-CTE
4096 × 2048
202 × 101
(3920,1848)
(354,155)
92.1
178
1Apertures are automatically created by commanding software when a HRC filter is used in WFC observations. (Apertures are not listed in the APT aperture pull-down menu.)
2Apertures are automatically created by commanding software when a polarizer filter is used. Same parameters apply for POL60 and POL120 in V and UV. (Apertures are not listed in the APT aperture pull-down menu.)


Table 7.7: Ramp filter apertures.
Filter
Ramp Segment
Full-frame apertures
Quadrant aperture
FR423N
FR716N
FR853N
FR5551N
FR647M
Inner
WFC1-IRAMP
WFC1-IRAMPQ
FR388N
FR656N
FR459M
FR647M
FR505N
FR914M
Middle
WFC1-MRAMP
WFC2-MRAMP
WFC1-MRAMPQ
WFC2-MRAMPQ
FR462N
FR782N
FR931N
FR1016N
FR601N
Outer
WFC2-ORAMP
WFC2-ORAMPQ

 7.7.2 Ramp Filter Apertures  7.7.4 Polarizer Apertures
Space Telescope Science Institute
http://www.stsci.edu
Voice: (410) 338-1082
help@stsci.edu