Star lost issue

stevesp

I’m guiding a C8HD at f7 or at f10 on AVX with a 70/400+Barlow 2x and a 290 MC. Exposure 2 sec at max gain. I’m in the balcony exposed to south as due to lockdown I cannot go out
I’m experiencing now a lot of star lost during guiding and sometimes during calibration as well
Looking to the screen the star doesn’t look changing but AAP doesn’t agree
what should I do? I was thinking if increasing exposure time could help to get a better star image but I’m afraid it can impact the guiding
what are the options?

w7ay

stevesp a 290 MC

I hate to suggest throwing good money after bad, but a mono camera might be just a tad better. The same camera in mono form will also have a finer image scale compared to a deBayered image.

If your camera comes with only an AR window, and if you can find a UV/IR cut filter in your drawer that fits your camera, you can try that too to raise the Signal To Noise ratio of the guide plate. Even if the window is IR cut, try adding a good IR cut filter anyway (pick a filter that is not sold by ZWO).

I was having a terrible time getting rid of stray light (even in a darken room at night) from my Mount Simulator setup (ASI174MM-mini) until I found that the "stray light" is coming right though my light box in the form of IR! A spare Baader "Moon and Skyglow" (which also acts as IR cut) cured it completely. With the stray background, ASIAIR could not plate solve the images from my mount simulator. With the Baader in place, ASIAIR consistenly plate solved in less than a second.

However, in your case, I would wait for the dust to settle first unless you have an IR cut filter that is hanging around unused. I have strong suspicions that the "star lost" are caused by camera software problems; perhaps caused by the image tearing that are very obvious visually, or bad frames that may not be obvious to us visually.

Chen

stevesp

Yesterday night I tried to increase the exposure length to 4 seconds and reduced the gain and I had very few star lost during the session. It wasn’t the right night due to the moonlight
now I have the next issue to solve as sometimes the guide moves Dec up and down a lot with unclear reason
One thing I found is that AAP can set guiding speed to sideral, solar and moon to my AVX but there is no additional setting like x0.9.... as I read about other mounts

PMTeam@ZWO

stevesp Regarding the issue of DEC movement, you can submit the log and we will fix your problem as soon as possible

stevesp

phd2-guidelog-2021-03-15-203215.txt

305kB

stevesp

What about the guiding speed?

Byrdsfan1948

stevesp If I understand your question correctly. The additional Guiding Rate(s) you are looking for are at the bottom of the Telescope Setting page, just above the Tracking Slider, and Go To Home Position button. In my case I have Guiding Rate options of 0.25X, 0.5X, 0.75X, 0.9X. Al

stevesp

Yes
they don’t appear in my AAP driving AVX

w7ay

stevesp they don’t appear in my AAP driving AVX

As I responded to you in the other thread which you had started about this issue (autoguide rate), ASIAIR does not use the AutoGuide rate from the NexStar AUX commands. Please check the threads that you had started.

For the NexStar protocol, ASIAIR uses the standard slewing commands to perform autoguiding, with slew rate set to 1x sidereal rate.

There is no autoguide rate to pick. It is always 1x for your mount.

The current ASIAIR v1.5.3 displays a window (when you are using the NexStar protocol, and probably the SynScan protocol too since they are identical - same Chinese company) with a "set to 1x" button in case your slew rate is currently set to some higher rate like 256x (which surely will eventually crash the OTA train into the pier).

ASIAIR only uses the NexStar protocol's Guide Rate (Sidereal, Solar and Lunar only, King rate is not available in SynScan/NexStar) in the NexStar AUX protocol. This is different from the AutoGuide Rate of the AUX protocol, that lets you set the auto guide rate to any integral percentage of sidereal rate.

1x autoguide rate is a bit too rough, especially when coupled with the latency of using 9600 baud, if you ask me. Any backlash, and you will start undamped motion even with aggressiveness turned way down.

I have seen ASIAIR issue guide pulses of just 4 or 5 milliseconds, while each character in the command sequence at 9600 baud itself takes 1 millisecond (and there are many characters for the complete start/stop slew commands). Those commands either undershoot or overshoot the correction by a lot.

Chen

stevesp

Yesterday I tried without Barlow and no star lost
i think that my problems are due to the poor sky I have from home, compared to the one on the mountains I was used
now I have to improve the guide as sometimes DEC follows its route
but I noticed something strange yesterday
AAP was guiding but when I started the auto run session it changed the guide star
It’s not the first time I notice this. What are the reasons? In the past I was thinking of a star lost situation, but yesterday it was ok
thanks