David's Astronomy Pages CCD Image Notes - Session 82 (2005-01-05)

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LX200 Tracking Problem - Counter Weight Balancing

I've previously had problems with tracking of my LX200 scope when pointing to certain parts of the NW sky.  Whilst I have a counter weight system installed on my LX200, I generally leave it in the position which gives optimal weighting of the scope when imaging the southern sky and generally don't move it as I move to different sky areas.  However the effects of this suboptimum weighting is occasionally expressed on images - for example in the following 2 min exposure.

Image with Sub-optimally Balanced LX200 Star field for 4U 0142+615 area  Altitude 52º / Azimuth 311º

CCD Image 2 min exposure,  C Filter 2004-12-29 00:43h UT (#81089)

The effects of suboptimal balancing were however particularly magnified during the session on 2005-01-05 because of the additional weight of an Pentax SLR camera mounted on top of the LX200.  Symptoms were an increase in noise from gears and jerky trailing of stars in images.  The marked effect on a 2 min exposure is shown below. 

Image with Poorly Balanced LX200 Star field for 1E 2259+586 area (stars are trailed to lengths of 40 arc secs) Altitude 36º / Azimuth 327º

CCD Image 2 min exposure,  C Filter 2005-01-06 00:10h UT (#82136)

Counter weights were repositioned and the image re-taken. The improvement is clear.

Image with appropriately counter weighted LX200  Star field for 1E 2259+586 area

CCD Image 2 min exposure,  C Filter 2005-01-06 00:16h UT (#82139)

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