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Well folks, Ive managed to get between the clouds and gather some more data. Noticed that the r/a drift got worse the further away the declination was from the south celestial pole. I believe this is due to K3ccdtools drift explorer measuring the dift with a constant field of view whilst the rate at which the stars move across a given field of view varies from almost zero near the scp to quite fast at zero declination (assuming the r/a drift is slower than the sidereal rate). If the r/a rate was perfect i.e. the same as the sidereal rate , then there would be no drift at all. Hence the error gets bigger the more positive the declination is. So I did a spreadsheet of the r/a drift error relative to the difference between the SCP and the declination setting and found a constant error which is about -1.5% of the sidereal rate so I'm convinced my mounts r/a drive is slow. Earlier I has tried to use the EQMOD custom rate (“comet button”) to correct this error but got “very fast” and “faster” results until I realised the default sidereal rate is +15.041067 which works fine in the northern hemisphere but down under the mount is postioned backwards pointing south so a minus sign is needed i.e. -15.041067. I didn't get enough time to test out adjusting the rate but preliminary tests indicate it will work. Have included a pic of the spreadsheet for any one with a calculator. Please let me know if there are errors.
Stephen
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