Performance of SIRPOL

LP mode

JHKs polarimetric images can be taken simultaneously.
Field of View:
7.7’ x 7.7’ (1k x 1k x 3 images, pixel scale=0.45”/pixel)
Sensitiveity (point source):
J=19.2, H=18.6, Ks=17.3 mag
(S/N=5, 15 min exp. in total for each waveplate angle)
Accuracy of Polarization Degree Meas.:
0.3 % for bright sources (J < 15.0, H < 14.5, Ks < 13.0 mag)
delta P < 1%: J < 16.5, H < 15.7, Ks < 14.5 mag
delta P < 3%: J < 17.5, H < 17.0, Ks < 15.7 mag
Accuracy of Polarization Angle Meas.:
better than 3 degree for bright sources (at J, H, and Ks)
Observation Efficiency:
100 min for typical 10 sec x 4 waveplate angles x 10 dither x 9 set obs.
(15 min exp. in total for each waveplate angle)
Shortest Exposure Time:
1.6 sec (depending on the shortest read-out time of the detectors)
Sky background at Ks:
300 - 400 ADU/sec when temperature is 20 degrees C
(at the same level as in the normal imaging mode)

Correction Angle:
105 degree at J, H, and Ks
Polarization Efficiency (last update: 28 Apr 2006):
95.5 % at J, 96.3 % at H, 98.5 % at Ks