WFC3/IR is a multi-accum detector. There are many timing sequences, with the possibility of using 1 to 15 reads for each. The total integration time depends on the type of timing sequence, the number of reads (NSAMP), and the size of the selected array. Subarrays have shorter integration times than full arrays for the same timing sequence name. The integration times are shown in tables in the Phase II Proposal Instructions.
The read noise depends on the NSAMP. The ETC uses a value of read noise that assumes NSAMP=15. It underestimates the read noise for smaller NSAMP. The ETC accepts or computes only a total integration time, so observers should check the possible integration times and keep in mind the assumption of NSAMP=15 for the read noise.
The following tables show the filter and disperser properties.
Name [1] |
Description [2] |
Pivot (A) [3] |
Width (A) [4] |
Peak Transmission |
---|---|---|---|---|
UVIS Long-Pass (LP) and Extremely Wide (X) Filters |
||||
F200LP |
Clear; grism reference |
5686.9 |
0.98 |
|
F300X |
Extremely wide UV |
2829.8 |
753.0 |
0.53 |
F350LP |
Long pass |
6812.0 |
0.98 |
|
F475X |
Extremely wide blue |
4917.1 |
2199.6 |
0.94 |
F600LP |
Long pass |
8430.2 |
0.99 |
|
F850LP |
SDSS z’ |
9756.4 |
0.96 |
|
UVIS Wide-Band(W) Filters |
||||
F218W |
ISM feature |
2183.0 |
351.7 |
0.23 |
F225W |
UV wide |
2341.0 |
547.3 |
0.32 |
F275W |
UV wide |
2715.3 |
480.8 |
0.46 |
F336W |
U, Stromgren u |
3361.1 |
553.8 |
0.75 |
F390W |
Washington C |
3904.6 |
953.0 |
0.96 |
F438W |
WFPC2 B |
4318.7 |
676.8 |
0.84 |
F475W |
SDSS g’ |
4760.6 |
1488.9 |
0.92 |
F555W |
WFPC2 V |
5309.8 |
1595.1 |
0.95 |
F606W |
WFPC2 Wide V |
5907.0 |
2304.2 |
0.99 |
F625W |
SDSS r’ |
6254.0 |
1575.4 |
0.95 |
F775W |
SDSS i’ |
7733.6 |
1486.0 |
0.85 |
F814W |
WFPC2 Wide I |
8304.7 |
2543.3 |
0.97 |
UVIS Medium-Band (M) Filters |
||||
F390M |
Ca II continuum |
3893.8 |
210.5 |
0.88 |
F410M |
Stromgren v |
4107.0 |
182.8 |
0.98 |
FQ422M |
Blue continuum |
4217.7 |
113.3 |
0.69 |
F467M |
Stromgren b |
4680.7 |
218.0 |
0.98 |
F547M |
Stromgren y |
5447.0 |
714.0 |
0.88 |
F621M |
11% passband |
6216.7 |
631.0 |
0.99 |
F689M |
11% passband |
6886.0 |
708.6 |
0.94 |
F763M |
11% passband |
7636.3 |
798.6 |
0.97 |
F845M |
11% passband |
8468.9 |
886.7 |
0.96 |
UVIS Narrow-Band (N) Filters |
||||
FQ232N |
C II] 2326 |
2326.9 |
32.2 |
0.12 |
FQ243N |
[Ne IV] 2425 |
2420.6 |
34.8 |
0.15 |
F280N |
Mg II 2795/2802 |
2796.8 |
22.9 |
0.27 |
F343N |
[Ne V] 3426 |
3438.0 |
140.0 |
0.78 |
F373N |
[O II] 3726/3728 |
3729.6 |
39.2 |
0.78 |
FQ378N |
z ([O II] 3726) |
3790.9 |
89.2 |
0.83 |
FQ387N |
[Ne III] 3868 |
3873.0 |
23.1 |
0.72 |
F395N |
Ca II 3933/3968 |
3953.7 |
72.9 |
0.86 |
FQ436N |
H 4340 + [O III] 4363 |
4366.7 |
35.7 |
0.67 |
FQ437N |
[O III] 4363 |
4370.6 |
24.6 |
0.70 |
F469N |
He II 4686 |
4687.5 |
37.2 |
0.69 |
F487N |
H 4861 |
4870.7 |
48.4 |
0.85 |
FQ492N |
z (H) |
4932.1 |
101.0 |
0.85 |
F502N |
[O III] 5007 |
5009.0 |
57.8 |
0.87 |
FQ508N |
z ([O III] 5007) |
5089.7 |
117.9 |
0.87 |
FQ575N |
[N II] 5754 |
5755.9 |
12.9 |
0.78 |
FQ619N |
CH4 6194 |
6197.5 |
61.6 |
0.89 |
F631N |
[O I] 6300 |
6303.0 |
43.1 |
0.86 |
FQ634N |
6194 continuum |
6347.5 |
66.2 |
0.88 |
F645N |
Continuum |
6451.6 |
85.0 |
0.86 |
F656N |
H 6562 |
6561.1 |
13.9 |
0.86 |
F657N |
Wide H + [N II] |
6565.1 |
96.3 |
0.90 |
F658N |
[N II] 6583 |
6585.2 |
23.6 |
0.92 |
F665N |
z (H + [N II]) |
6654.4 |
109.0 |
0.90 |
FQ672N |
[S II] 6717 |
6716.1 |
14.9 |
0.89 |
F673N |
[S II] 6717/6731 |
6764.5 |
100.5 |
0.91 |
FQ674N |
[S II] 6731 |
6729.5 |
10.0 |
0.68 |
F680N |
z (H + [N II]) |
6878.6 |
323.6 |
0.95 |
FQ727N |
CH4 7270 |
7274.7 |
64.8 |
0.89 |
FQ750N |
7270 continuum |
7500.6 |
68.8 |
0.85 |
FQ889N |
CH4 25 km-agt [5] |
8891.8 |
93.7 |
0.90 |
FQ906N |
CH4 2.5 km-agt |
9056.7 |
94.0 |
0.92 |
FQ924N |
CH4 0.25 km-agt |
9246.3 |
89.2 |
0.94 |
FQ937N |
CH4 0.025 km-agt |
9371.1 |
91.9 |
0.91 |
F953N |
[S III] 9532 |
9529.7 |
84.6 |
0.90 |
UVIS Grism (G) |
||||
G280 |
UV Grism |
1850 |
0.4 |
Name [6] |
Description |
Pivot [7] (nm) |
Width [8] (nm) |
Peak Transmission |
---|---|---|---|---|
IR Wide-Band(W) Filters |
||||
F105W |
Wide Y |
1048.95 |
292.30 |
0.98 |
F110W |
Wide YJ |
1141.40 |
503.40 |
0.99 |
F125W |
Wide J |
1245.90 |
301.50 |
0.98 |
F140W |
Wide JH gap; red grism reference |
1392.10 |
399.00 |
0.99 |
F160W |
WFC3 H |
1540.52 |
287.88 |
0.98 |
IR Medium-Band(M) Filters |
||||
F098M |
Blue grism reference |
982.93 |
169.48 |
0.97 |
F127M |
H2O/CH4 continuum |
1273.64 |
68.79 |
0.98 |
F139M |
H2O/CH4 line |
1383.80 |
64.58 |
0.98 |
F153M |
H2O and NH3 |
1533.31 |
68.78 |
0.98 |
IR Narrow-Band(N) Filters |
||||
F126N |
[Fe II] |
1258.26 |
11.83 |
0.90 |
F128N |
Paschen |
1283.30 |
13.54 |
0.94 |
F130N |
Paschen continuum |
1300.62 |
13.28 |
0.96 |
F132N |
Paschen (redshifted) |
1319.04 |
13.07 |
0.91 |
F164N |
[Fe II] |
1645.13 |
17.48 |
0.93 |
F167N |
[Fe II] continuum |
1667.26 |
17.16 |
0.93 |
IR Grisms (G) |
||||
G102 |
“Blue” high-resolution grism |
250 |
||
G141 |
“Red” low-resolution grism |
600 |
See Footnote 1 of UVIS table for naming conventions.
“Pivot wavelength” is defined as in Table 6.2. All wavelength measurements in this table were made in air.
Full width at 50% of peak transmission.
Spatial scan mode is available for IR imaging observations, IR spectroscopic observations, and UVIS imaging observations. The target is moved along the detector at a fixed rate during the exposure time. The ETC requires a pair of input parameters to describe the scan: either scan rate (arcsec per sec) and scan length (arcsec) or exposure time (sec) and scan length (arcsec). For the imaging modes, the height and width of the region that will be used for SNR calculations is selected. For the IR spectroscopic mode, only the height of the region is selected. For that mode, the width will be 1 pixel for computing the count rate and one spectral resolution element (2 pixels) for computing counts.
The scan rate can be any number between 0.0 and 7.84 arcseconds/sec. Rates higher than 5 arcseconds/sec are performed under gyro control. The scan length or exposure time should be chosen to fit the array or subarray used for the exposure.