ASIAIR Plus

ZWO ASIAIR Plus Equipment Guiding Troubleshooting
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Jerry Gerber avatar
Jerry Gerber avatar
Hello!

I love the ASIAIR Plus but ZWO has not produced a user manual for it.  The ASIAIR Pro manual is not only outdated, but it leaves out many of the settings and what they do.  

In any event, here's my question:  With my 100mm refractor I've been getting terrific autoguiding numbers, down as low as .27" and .34".  The other night I was set up and did my polar alignment.  I got it very close, within 50 arc-seconds on both Alt and AZ axis.  But my guiding numbers were moving all over the place, sometimes as low as .4" and other times around .9" all the way up to over 1" (usually on the RA axis).  It didn't seem very windy at all, at least on the ground, and the clear sky chart in my region was reporting good seeing conditions.  Yet my guiding was relatively unstable, at least in comparison to other imaging sessions. 

Though I managed to get a good image with the stars looking good, I am wondering if there's a factor or parameter that I've overlooked.  I spent the evening I just described changing the aggression settings on the RA and DEC axis, but this generally did not help a lot, or it would help but then a few minutes later the guiding numbers started creeping up again. 

What might cause this?

Jerry
Well written Engaging
TurtleCat avatar
TurtleCat avatar
I find this happens to me periodically and I've gone from looking at it to not worrying about it if it is just here and there. Might be a cable pinch, could be a bird landing on it, all sorts of things. My typical is around 0.5 with my AM5. I've gotten lower and I've had higher. I always seem to end up with 2.7 pixel FWHM so I just go with it. I've looked at a number of PHD2 recommendations and things and many of the better ones just keep telling me not to obsess about the numbers unless it shows up in the resulting images. Seems to work for me smile
Jerry Gerber avatar
Jerry Gerber avatar
I find this happens to me periodically and I've gone from looking at it to not worrying about it if it is just here and there. Might be a cable pinch, could be a bird landing on it, all sorts of things. My typical is around 0.5 with my AM5. I've gotten lower and I've had higher. I always seem to end up with 2.7 pixel FWHM so I just go with it. I've looked at a number of PHD2 recommendations and things and many of the better ones just keep telling me not to obsess about the numbers unless it shows up in the resulting images. Seems to work for me

Yeah, that's good advice.   What guiding exposure do you usually work at?   Have you tried making adjustments to the Calibration Step rate?  I can't find any information about how Calibration Step and focal length of guide scope (my guide scope has a focal length of 242mm).  Thanks TurtleCat!
TurtleCat avatar
TurtleCat avatar
Jerry Gerber:
I find this happens to me periodically and I've gone from looking at it to not worrying about it if it is just here and there. Might be a cable pinch, could be a bird landing on it, all sorts of things. My typical is around 0.5 with my AM5. I've gotten lower and I've had higher. I always seem to end up with 2.7 pixel FWHM so I just go with it. I've looked at a number of PHD2 recommendations and things and many of the better ones just keep telling me not to obsess about the numbers unless it shows up in the resulting images. Seems to work for me

Yeah, that's good advice.   What guiding exposure do you usually work at?   Have you tried making adjustments to the Calibration Step rate?  I can't find any information about how Calibration Step and focal length of guide scope (my guide scope has a focal length of 242mm).  Thanks TurtleCat!

My current guidescope (will be upgrading next month most likely) is the Zwo 30mm (120mm focal length) and I use the ASI 290 mini. I have the calibration step set to 1300 and exposures at 1 second. Everything else is at the default. A piece of advice which I also followed (you can do it manually but why?) is to open the phd2 app and go to the advanced settings. You can put in your guide scope and guide cam parameters and it will tell you what you should use for calibration. Basically, in the end, you want each calibration pulse step to move just a little. 

Also it’s good to make sure you use asiair’s ability to build a dark library for your guide cam and to ensure you calibrate closer to the celestial equator. If you don’t move your guide cam you can save the calibration and reuse. A lot easier to deal with. Also if you are going to image near the meridian, first move the scope to an object nearer the equator and start guiding there before moving to your subject.
Helpful
Jerry Gerber avatar
Jerry Gerber avatar
Jerry Gerber:
I find this happens to me periodically and I've gone from looking at it to not worrying about it if it is just here and there. Might be a cable pinch, could be a bird landing on it, all sorts of things. My typical is around 0.5 with my AM5. I've gotten lower and I've had higher. I always seem to end up with 2.7 pixel FWHM so I just go with it. I've looked at a number of PHD2 recommendations and things and many of the better ones just keep telling me not to obsess about the numbers unless it shows up in the resulting images. Seems to work for me

Yeah, that's good advice.   What guiding exposure do you usually work at?   Have you tried making adjustments to the Calibration Step rate?  I can't find any information about how Calibration Step and focal length of guide scope (my guide scope has a focal length of 242mm).  Thanks TurtleCat!

My current guidescope (will be upgrading next month most likely) is the Zwo 30mm (120mm focal length) and I use the ASI 290 mini. I have the calibration step set to 1300 and exposures at 1 second. Everything else is at the default. A piece of advice which I also followed (you can do it manually but why?) is to open the phd2 app and go to the advanced settings. You can put in your guide scope and guide cam parameters and it will tell you what you should use for calibration. Basically, in the end, you want each calibration pulse step to move just a little. 

Also it’s good to make sure you use asiair’s ability to build a dark library for your guide cam and to ensure you calibrate closer to the celestial equator. If you don’t move your guide cam you can save the calibration and reuse. A lot easier to deal with. Also if you are going to image near the meridian, first move the scope to an object nearer the equator and start guiding there before moving to your subject.

I started autoguiding with the ZWO 30mm guide scope as well  using the same camera, the asi290mini.  I was having some issues, so I replaced the ZWO guidescope with the Skywatcher Evoguide 50 ED and found it worked far better.   You create darks for your guide camera?  I've never heard of that before!
Engaging
dkamen avatar
dkamen avatar
Hot pixels may be mistaken for stars and thermal patterns may mess with star profiles and star position calclulation (kind of like bad seeing). Darks help with both. Not always a real problem but they definitely do no harm.
Helpful Concise
TurtleCat avatar
TurtleCat avatar
Jerry Gerber:
Jerry Gerber:
I find this happens to me periodically and I've gone from looking at it to not worrying about it if it is just here and there. Might be a cable pinch, could be a bird landing on it, all sorts of things. My typical is around 0.5 with my AM5. I've gotten lower and I've had higher. I always seem to end up with 2.7 pixel FWHM so I just go with it. I've looked at a number of PHD2 recommendations and things and many of the better ones just keep telling me not to obsess about the numbers unless it shows up in the resulting images. Seems to work for me

Yeah, that's good advice.   What guiding exposure do you usually work at?   Have you tried making adjustments to the Calibration Step rate?  I can't find any information about how Calibration Step and focal length of guide scope (my guide scope has a focal length of 242mm).  Thanks TurtleCat!

My current guidescope (will be upgrading next month most likely) is the Zwo 30mm (120mm focal length) and I use the ASI 290 mini. I have the calibration step set to 1300 and exposures at 1 second. Everything else is at the default. A piece of advice which I also followed (you can do it manually but why?) is to open the phd2 app and go to the advanced settings. You can put in your guide scope and guide cam parameters and it will tell you what you should use for calibration. Basically, in the end, you want each calibration pulse step to move just a little. 

Also it’s good to make sure you use asiair’s ability to build a dark library for your guide cam and to ensure you calibrate closer to the celestial equator. If you don’t move your guide cam you can save the calibration and reuse. A lot easier to deal with. Also if you are going to image near the meridian, first move the scope to an object nearer the equator and start guiding there before moving to your subject.

I started autoguiding with the ZWO 30mm guide scope as well  using the same camera, the asi290mini.  I was having some issues, so I replaced the ZWO guidescope with the Skywatcher Evoguide 50 ED and found it worked far better.   You create darks for your guide camera?  I've never heard of that before!

It was a feature of the 2.0 software. I did it before I read that it can be helpful, lol. I have an askar 40mm apo guidescope on order so hopefully it will give me just a bit more goodness
Jerry Gerber avatar
Jerry Gerber avatar
Jerry Gerber:
Jerry Gerber:
I find this happens to me periodically and I've gone from looking at it to not worrying about it if it is just here and there. Might be a cable pinch, could be a bird landing on it, all sorts of things. My typical is around 0.5 with my AM5. I've gotten lower and I've had higher. I always seem to end up with 2.7 pixel FWHM so I just go with it. I've looked at a number of PHD2 recommendations and things and many of the better ones just keep telling me not to obsess about the numbers unless it shows up in the resulting images. Seems to work for me

Yeah, that's good advice.   What guiding exposure do you usually work at?   Have you tried making adjustments to the Calibration Step rate?  I can't find any information about how Calibration Step and focal length of guide scope (my guide scope has a focal length of 242mm).  Thanks TurtleCat!

My current guidescope (will be upgrading next month most likely) is the Zwo 30mm (120mm focal length) and I use the ASI 290 mini. I have the calibration step set to 1300 and exposures at 1 second. Everything else is at the default. A piece of advice which I also followed (you can do it manually but why?) is to open the phd2 app and go to the advanced settings. You can put in your guide scope and guide cam parameters and it will tell you what you should use for calibration. Basically, in the end, you want each calibration pulse step to move just a little. 

Also it’s good to make sure you use asiair’s ability to build a dark library for your guide cam and to ensure you calibrate closer to the celestial equator. If you don’t move your guide cam you can save the calibration and reuse. A lot easier to deal with. Also if you are going to image near the meridian, first move the scope to an object nearer the equator and start guiding there before moving to your subject.

I started autoguiding with the ZWO 30mm guide scope as well  using the same camera, the asi290mini.  I was having some issues, so I replaced the ZWO guidescope with the Skywatcher Evoguide 50 ED and found it worked far better.   You create darks for your guide camera?  I've never heard of that before!

It was a feature of the 2.0 software. I did it before I read that it can be helpful, lol. I have an askar 40mm apo guidescope on order so hopefully it will give me just a bit more goodness

I think it will.  The ZWO guide scope is too small for a 100mm refractor.     I think I did notice the dark library option with guiding,  I'll try it and see if it improves guiding..
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