Direct Mount Unguided Dithering: Slew Possible, or Only Pulse?

Is it possible to use direct mount unguided dithering to slew-dither rather than pulse-dither?

I understand 10 Micron mounts need this to retain refraction updates. MaximDL, ACP, and CCD Autopilot support Slew or Move Axis dither. Does SGP?

Currently the Direct Mount Guider is implemented as a pulse guide command. I would assume that the mount would internally keep track of position based off of this? I’m not entirely sure how this would be different from a random slew?

Thanks,
Jared

Jared,

It is my understanding that the algorithm for 10 Micron performs important refraction compensation, and that this is lost by pulse guiding. Slew guiding, or move axis retains this critical feature, and thus is implemented as such in other software. This is a commonly unknown caveat with unguided dithering, and it is unfortunate that more users are not aware. Basically, it means I can’t use SGP for unguided dithering with a 10 Micron mount.

Here is a slide from a youtube presentation on 10 Micron and unguided dithering:

I’m not sure your interpretation is correct. In the past, refraction was typically updated when the mount was slewing. Now, you have a variety of options including continuously. See the text from the 10micron Ascom driver :
Check “Enable refraction data update” to send automatically to
the mount the refraction parameters. The refraction parameters
are read from a text file which can be written automatically
by some weather station applications such as MGBox and StickStation.

When the file is updated, and the selected condition is matched,
the atmospheric pressure and temperature are uploaded to the mount.

Available conditions are:
continuously:
upload data as soon as they are available.
only when the mount is slewing:
send the data only when the mount is slewing to a target,
so tracking isn’t affected.
only when the mount is slewing or guiding:
send the data only when the mount is slewing to a target,
or a pulseguide command is being sent, so tracking is
affected only if you are currently guiding.

We can probably provide an option to use the MoveAxis command in the future.

Thanks,
Jared

Jared,

Just to confirm, refraction updates are not applied when pulse dithering is used, correct?

Thanks,

Kris

I’m not sure. That’s more of a question for your mount manufacturer. I’m not sure how they handle pulse commands in their driver.

Thanks,
Jared

In the interest of closure, I received the following information from 10Micron:

"You can apply the the refraction updates whenever you want.

If you have a stickstation or something like that, and if you use the 10Mciron ASCOM driver, you have 3 options about the refraction data:

1 - Always (applied on slewing, tracking, guiding)

2 - Slewing only

3 - Slewing and guiding but not in tracking only

Frejvall’s ASCOM driver works a little bit different (there’s a checkbox “update refraction continuously”)"