BYEOS dithering problem

[gmartin02]

Setup:

 

Computer HP laptop w/Dual-Core A4-3305M

Telescope control: NexRemote software

Camera control: BYEOS Pro v3.10

Guiding software: PHD2 v

Guiding camera: SX Lodestar

ASCOM Platform 6 - SP1

ASCOM Celestron Telescope Driver: 5.0.30

ASCOM SX Camera Driver 5.5.1.13082

Laptop connection to camera: 5 meter USB cable

Laptop connection to mount: 5 meter USB cable->Active USB hub->1 meter USB cable ->Keyspan USB-Serial adapter->serial cable->serial port on bottom of Nexstar hand controller

 

 

I usually send the guide commands from PHD2 "on camera" (through the SX Lodestar to the ST-4 cable into the guiding port on the mount). I have never had an issue dithering from BYEOS when using this setup.

 

Last night I was unable to get PHD2 to connect to the mount with the "on camera" setting, so instead I connected PHD2 to the mount using ASCOM. 

 

Guiding and BYEOS dithering worked perfectly through ASCOM, except for one problem:

 

For about 1/3 of the images, exactly at the point that BYEOS dithering ends and the BYEOS "cool down" period starts, PHD2 reported "star lost". Each time this happened, I had to stop PHD2 guiding, re-select the guide star, and restart guiding.

 

At no other time did PHD2 have any problems staying locked on the guide star - only at the end of BYEOS dithering.

 

 

Has anyone experienced this type of problem before? Could BYEOS be sending a "bad" command to PHD2 at the end of dithering that is causing the problem? Should I upgrade the ASCOM platform and/or Camera/Telescope ASCOM drivers?

 

Any help would be appreciated,

 

Greg 

 

[gmartin02]

I finally got a clear, moonless night to do some more experimenting.

 

I first tried increasing the "Star Mass Tolerance" in PHD2, but was still having the same problem.

 

Then I turned off "Star Mass Change Detection" completely, and the problem went away. I got 27 straight frames without any guiding glitches - hurray! Problem solved.

 

 

Guylain, thank you so much for the suggestion. You are a life saver, or at least a sleep saver - I can now take my late night nap during imaging while guiding with the OAG & using the LP filter in front of the OAG.

[s3igell]

You have a slightly mistaken understanding of the Dither action and the roles that PHD2 and BYE play.

BYE uses the "older" PHD Communication Protocol - the Socket Server Protocol - in order to be compatible with both PHD1 and PHD2.

BYE will, after an Exposure has Completed and the Shutter is Closed, request that PHD2 perform a Dither (using the BYE Dither Aggressiveness setting to request a size of Dither).  It then loops requests to PHD2 to report the current Guider Error in Pixels, until that Guider Error is below the BYE "Settle Dither at" value.  BYE will then wait the BYE "Calm down period" time in seconds before starting the next Image Capture sequence.

 

BBYE has no interaction with PHD2 after the "Settle Dither at" value is reached, and really no input into PHD2's actions except the Dither request at the start of the process.  BYE has no automated control over the Mount, so it cannot even be accused of "Moving the Star out from under PHD2".

 

As always, it is wise to keep Up-to-Date on Drivers and ASCOM components.

 

One might start by reviewing both the PHD2 and ASCOM Mount Logs at the times of these Star Lost episodes, to find details about the Conditions and any possible Actions or Errors which were logged.

[astroman133]

You might also play around with PHD2's Manual dither command to see if it duplicates the symptoms that you see when BYE requests a dither.

[astroman133]

One thought did occur to me...

 

Depending on what the current values for MaxDec and MaxRA are you may want to consider bumping them up to around 2000.  It may be that you are losing the star because dithering moves are more than the guiding can follow.

[admin]

What about increasing the guide -square-?

[gmartin02]

Tonight I got my ST-4 Lodestar cable working again, and I had the same problem, so I don't think it is an ASCOM thing.

 

From the first, I didn't really think it was caused by BYEOS, but suspected it was something else.

 

I did change one other thing when the problem began occurring: I am guiding through a filter (2" IDAS LPD1 in front of the OAG, instead of a clip-in filter behind the OAG), which reduces contrast. I think that is causing my issue. 

 

I did just try to increase the size of the search box, but that didn't help either.

 

I'm going to try some of the other suggestions above.

 

Thanks everyone for the thoughtful responses.

 

Greg

[admin]

Bring the star mass detection way down.  Several times PHD would lose the guide star due to low star mass when, to my eyes, there was plenty.

 

I have set my star mass detection value way down to 0 and it worked for me.