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TRISPEC sensivity (UKIRT f/36)
TRISPEC Sensitivity (UKIRT f/36)
These are preliminary results estimated from the UKIRT observartion at
August 2000. The following sensitivities is based on the mesured throughput,
readnoise, dark current of TRISPEC, the sky brightness, and the predicted
photon noise. Please note that because of the poor weather condition
and the some uncertainty of the detecter gain, the some uncertainty
can be still remained in the following sensitivities.
Imaging mode:
Surface Brightness
1 sigma magnitudes; per pixel
| Filter |
Exposure Time (seconds) |
| |
1 |
10 |
60 |
100 |
600 |
3600 |
| V |
22.4 |
24.7 |
26.0 |
26.4 |
27.4 |
28.4 |
| J |
20.9 |
23.1 |
24.4 |
24.6 |
25.7 |
26.7 |
| Ks |
19.7 |
21.8 |
23.1 |
23.4 |
24.4 |
25.4 |
Point source
10 sigma magnitudes;
seeing: 0.9" (V), 0.7" (J, Ks); aperture: 2" (V), 1.8" (J, Ks)
| Filter |
Exposure Time (seconds) |
| |
1 |
10 |
60 |
100 |
600 |
3600 |
| V |
16.5 |
18.8 |
20.2 |
20.6 |
21.6 |
22.6 |
| J |
16.0 |
19.6 |
19.5 |
19.8 |
20.8 |
21.8 |
| Ks |
14.8 |
17.0 |
18.3 |
18.6 |
19.6 |
20.6 |
Imaging polarimetry mode:
Surface Brightness
283 sigma (polarization accuracy of 0.5%) magnitudes;
per pixel
| Filter |
Exposure Time (seconds) |
| |
1 |
10 |
60 |
100 |
600 |
3600 |
| V |
16.3 |
18.6 |
19.9 |
20.3 |
21.3 |
22.3 |
| J |
14.8 |
17.0 |
18.3 |
18.5 |
19.6 |
20.6 |
| Ks |
13.6 |
15.7 |
17.0 |
17.3 |
18.3 |
19.3 |
Point Source
283 sigma (polarization accuracy of 0.5%) magnitudes;
seeing: 0.9" (V), 0.7" (J, Ks); aperture: 2" (V), 1.8" (J, Ks)
| Filter |
Exposure Time (seconds) |
| |
1 |
10 |
60 |
100 |
600 |
3600 |
| V |
12.9 |
15.2 |
16.6 |
17.0 |
18.0 |
19.0 |
| J |
12.4 |
16.0 |
15.9 |
16.2 |
17.2 |
18.2 |
| Ks |
11.2 |
13.4 |
14.7 |
15.0 |
16.0 |
17.0 |
Spectroscopy mode with the low dispersion grisms:
Point Source
10 sigma magnitudes;
0.88" slit; seeing: 0.8" (0.55, 1.25µm), 0.7" (2.15µm);
aperture: 2.1"(0.55µm), 2"(1.25, 2,15µm)
| wavelength (µm) |
Exposure Time (seconds) |
| |
1 |
10 |
60 |
100 |
600 |
3600 |
| 0.55 |
12.7 |
15.2 |
17.0 |
17.5 |
18.9 |
20.0 |
| 1.25 |
12.3 |
14.7 |
16.5 |
17.0 |
18.2 |
19.3 |
| 2.15 |
10.0 |
12.5 |
14.2 |
14.6 |
15.8 |
16.9 |
Spectro-polarimetry mode with the low dispersion grisms:
Point Source
283 sigma (polarization accuracy of 0.5%) magnitudes;
0.88 slit; seeing: 0.8" (0.55, 1.25µm), 0.7" (2.15µm);
aperture: 2.1"(0.55µm), 2"(1.25, 2,15µm)
| wavelength (µm) |
Exposure Time (seconds) |
| |
1 |
10 |
60 |
100 |
600 |
3600 |
| 0.55 |
9.1 |
11.6 |
13.4 |
13.9 |
15.3 |
16.4 |
| 1.25 |
8.7 |
11.1 |
12.9 |
13.4 |
14.6 |
15.7 |
| 2.15 |
6.4 |
8.9 |
10.6 |
11.0 |
12.2 |
13.3 |
Notes
-
The sensitivities assume that the subtraction of background (eg.
sky frame) are not necessary. If the subtraction of background are necessary,
then the sensitivities are lower by 0.4 mag than those given in all the
Table.
-
For point sources if image quality improves and smaller apertures can be
used the sensitivity goes up, e.g. if a 1" apertures can be used, the signal
stays the same, the noise decreases by a factor of two, and the sensitivities
improve by 0.7 mag.
-
For surface brightness with other apertures increase the signal by
the increase in area, increase the noise by the square root of the
increase in area, and hence increase the S/N by the square root of the
increase in area.
Last Modification Date: 2000/09/26
Last Modification Author: Makoto
Watanabe <watanabe@z.phys.ngaoya-u.ac.jp>
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