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angular distance moved is limited by both the maximum angular rate and the maximum angular acceleration. If we imagine the max angular rate is 3 deg/s and max angular acceleration is 3.5 deg/s/s, then to move one field width requires a slew of 3 degrees in angle (gives small overlap). For no coast phase this takes a time given by t=2*sqrt(2*1.5deg/alpha)=2 seconds. The maximum angular rate achieved is omega=alpha(1)=3 deg/sec. So for these parameters for any slew larger than a field width, we are angular-rate-limited, and the slew requires a time t_slew~2+dtheta/3 seconds. IF we can slew during readout, the overhead between images separated by an angle theta then is approximately (2+theta/3) seconds.

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Operating on the meridian in this mode, with 15 second exposures we'll assume it would take 20 seconds total on average, per exposure. It would take 24*(3.1/360)~12 minutes for the sky to move by one field width, on the equator.  In the course of 12 minutes we can acquire 12minutes*3images/min=36 images on the meridian. At this half-overlap rate we could cover 36*3.1/2~56 degrees.

Chuck says settling time is of order 1 sec. 

 

Coverage Rate

At 35 seconds per visit and 9.6 square degrees per field, we cover the sky at a rate of 7900 square degrees in an 8 hour night. That means that on average we revisit interval (no weather) is 3 days for 18,000 square degrees.  

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