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Old 11-06-2012, 10:36 AM
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PRejto (Peter)
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Join Date: Jan 2011
Location: Rylstone, NSW, Australia
Posts: 1,397
Finally the weather improved, though briefly, and I could continue some testing. I was able to "successfully" guide using a direct guiding cable from Bintel, though I needed to turn T-Point off in TSX to prevent the mount from disconnecting from TSX. I attempted pulse guiding through PHD but gave up when - immediately after calibration - TSX turned off MX tracking for some reason. I tried direct guiding straight away - since it seemed to work ok I didn't try pulse guiding again.

I put "successfully" in quotes because I'm not actually sure about my results. I took 2 images...one guided for 5 min, the other for 10 min.

The 5 min guided image looks pretty good, and CCDInspector showed fairly round stars: aspect = 7% (without a flattener).

The 10 min shot was not very good! Aspect = 47%

I'm attaching an image that shows a portion of the 10 min guided shot along with another picture showing the same field with RA turned off for 30 sec. I'm not sure what conclusion I can draw from this, if any. The guiding error looks to be both in RA and DEC. My PA on the MX is as follows: MA = 0, ME = 0, but suggests raising 1.3 tics to get 84" from refracted pole. I seem to be chasing this value even when I move the polar axis by half the value so I have not tried hard to refine this. Is PA error part of what I am seeing in 10 min guided or would I not expect to see that error unless I was guiding considerably longer?

The guiding was just with the default settings in PHD. Based on the 10 min guided shot can anyone recommend different settings I might try? (I couldn't detect any motion of the guide star in PHD during the 10 min exposure.) What is a "reasonable" expectation re guiding with PHD/Orion SSAG/PMX...that is how long should I be able to guide? What do I aim for here?

Thanks! Any help muchly appreciated with this
Attached Thumbnails
Click for full-size image (10 min guided + 30 sec RA off.jpg)
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Last edited by PRejto; 11-06-2012 at 10:46 AM.
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