Re: Bad images _Bouncing stars

Mike Shade

As I offered I had some weirdness with my setup.  After much fidgeting and greasing the gears and a new PEC curve, I can go 382" (the worm period) and get round stars near zenith unguided.  I could go 300", but that wasn't a complete worm cycle.  This suggests strongly that the weirdness was not the mount.  A good place to start to see what your mount can do.


Mike J. Shade

Mike J. Shade Photography:


In War: Resolution

In Defeat: Defiance

In Victory: Magnanimity

In Peace: Goodwill

Sir Winston Churchill

Already, in the gathering dusk, a few of the stars are turning on their lights.

Vega, the brightest one, is now dropping towards the west.  Can it be half

a year since I watched her April rising in the east?  Low in the southwest

Antares blinks a sad farwell to fall...

Leslie Peltier, Starlight Nights


International Dark Sky Association:


From: [] On Behalf Of John Thompson via
Sent: Tuesday, April 28, 2020 3:34 PM
Subject: Re: [ap-gto] Bad images _Bouncing stars


I apologize. I should have provided more information in my "bouncing stars"post. It's an AP 1600 mount (no Encoders) with a TEC140 F/7 scope with a FLI Atlas focuser. It's running Maxim for the main camera, SBIG STF-8300 and PHD for the guide camera, a SBIG ST-i. I am using APCC Pro with SkyX for the planetary program. The focus program is FocusMax. The session runs auto using CCDAutoPilot5. I am shooting LRGB 10 images each filter @ 600 sec using a 5 pixel dither between images. PHD is running RA and DEC in Hyperstasis with a 60 aggression setting with 3 sec exposures with dithering. Actually the guiding looks very good with very few corrections and a low RMS. I don;t believe the guide star is lost at any time but dithering might be an issue. I will look at the guide logs for any clues. The only time I see something "funny" is during the dithers. But the guiding stops during the dithers and then re-aguires the guide star.

The night was almost perfect, 5 by 5. No clouds or wind (3 MPH max) All cables are routed through the mount and appear ok.

I may try some imaging at 600 sec with no guiding tonight and some with no dithering. Thank you all for the comments. Any other ideas are appreciated.

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