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

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

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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

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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

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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.

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Last Modification Date: 2000/09/26 Last Modification Author: Makoto Watanabe <watanabe@z.phys.ngaoya-u.ac.jp>