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.
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.) |
Space Telescope Science Institute http://www.stsci.edu Voice: (410) 338-1082 help@stsci.edu |