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I keep getting a warning about being far from the celestial equator when I start calibration. The problem is I have a limited view of the sky from my shooting location this time of year and I can't point anywhere near the celestial equator. Guiding still seems to work so I am wondering what that warning is about. |
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The PHD2 devs recommend calibrating no further than 20 degrees from DEC 0 and as high in altitude as possible but if you can't you can't. If your guiding has been adequate just ignore the warning. I personally have always calibrated where ever I was imaging and never had problems. I recently made a point to calibrate at dec 0 and have seen no difference in guiding performance but everyone's gear is different. |
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I receive that warning on occasion and mostly ignore it if I'm happy with how my guiding is going. Worth keeping it in mind though as if I have guiding issues I know to try recalibrating as per the ASIAir/PHD instructions as a possible fix. |
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My initial guiding quality is fine both ways. I do believe I get better stability over the night as the performance does not decrease that much |
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I, too, calibrate my guiding after I slew to my target in spite of the warning. The guiding seems absolutely fine. Greg |
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Thanks everyone. You are all confirming what I thought. It's just a warning, it's best to do it close to the celestial equator but not mandatory. |
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Hmm! I wonder if this is the cause of my recent guiding issue. On consesutive nights I ran the same rig with the same guiding settings, but the guiding on the 2nd night had PHD2 changing from ~2 sec to <0.5 sec updates with a 2000ms setting. Changes to the refresh time (now set at 5000ms) made no difference. Over the 5 hours, though, there was a steady drift of the field to the point where my stacking routine just gave up, and PHD2 didn't report anything unusual! I'm wondering whether I had got my guiding working at a point much closer to the equator on the first night, whereas I did it near my target at ~-70deg. on the 2nd night. As this was about a month ago, I can't remember that sort of detail. I'll have to try it out and let you know. Paul. PS Apologies in advance: this is a bit off your original topic, but might be of interest to others. Let me know if I should start up another topic. Update: No, this isn't the same issue. This is simple user error (I say with a red face!). In the PHD2 calibration screen, I (somehow) had selected the 0.5sec exposure time. I've now put it at 3sec and all is working well. A 6-hour ap session last night couldn't have gone better! I did, however, calibrate my PHD2 while pointing at Achernar (Dec -57d), rather than the -70d of NGC2070 (Tarantula Neb.). Total RMS error for the night seems to have been mostly between 0.5" and 0.8". |