Target Acquisition

Acquiring targets

• Maximum slew speed: 0.5 deg/s
• Rotator speed: 1.5 deg/s
• Blind pointing accuracy: < 1.0'' rms over most of sky
• Field of view of auto guider (AG) probe: 30'' with 0.07'' positional accuracy (without seeing error)
• Target visibility

The pointing accuracy of Subaru Telescope is 6'' in the worst case which should be sufficient for all imaging observations, even with the smallest fields of view. However, observers are recommended to bring finding charts (preferably taken in similar filters to those of their planned observations) in order to catch possible typos in their target coordinates.

For spectroscopic observations, short acquisition images must always be taken to ensure that the target is in the spectroscopic slit. If your targets are visible in these images, offsets are not required; the lengths of the acquisition images vary from instrument to instrument, but if you cannot obtain a highly significant detection of your target in a 60-second exposure, you should prepare offsets from nearby bright (preferably compact) objects within the field of view of the instrument. These offsets should be provided in a coordinate frame where the slit is aligned with one of the axes.

Acquisition Guiding Accuracy

The acquisition guiding accuracy is about 0.1 arcsecond with influences of seeing. The limiting magnitude for guide stars is about 18th at all foci (Usuda et al. 2002). The AG camera detects light of λ = 0.73 ± 0.08 μm.