EQASCOM pulse guide setting

[swag72]

Can anyone tell me what the default pulse guide rate setting is within EQMOD? I know that there are the two sliders that you can use in RA and DEC that allows you to specify the speed rate of the pulseguide between x0.1 and x0.9 of the sidereal rate, but what is the sidereal rate and can it be changed?

The slider in the EQMOD menu is for ST4 guiding, which I think will be useless to me if I'm not using an ST4 connection.

[themos]

sidereal rate is 15 arcseconds per second. Have a look here 

http://www.wilmslowastro.com/software/formulae.htm#GuiderRate

[dmahon]

Sidereal rate is basically the speed which the fixed (distant) stars appear to move across the sky.

Changing the speed of the earth's rotation or it's orbit around the sun would be a massive feat of engineering.

[swag72]

sidereal rate is 15 arcseconds per second. Have a look here 

http://www.wilmslowastro.com/software/formulae.htm#GuiderRate

Is that x0.25? There's a mountain of formula's and different measurement parameters out there.

[swag72]

Sidereal rate is basically the speed which the fixed (distant) stars appear to move across the sky.

Changing the speed of the earth's rotation or it's orbit around the sun would be a massive feat of engineering.

Sorry I'm probably being very stupid here! How does this help me with regards to knowing the default sidereal rate used by ASCOM pulse guiding?

[themos]

There is no "default sidereal rate" as the sidereal rate is always 15 arcseconds per second (well, 15.04 apparently). What there is is a default fraction of the sidereal rate that EQMOD pulse guiding uses before the user explicitly sets it. I think the default is 0.5x, so half the sidereal rate or 7.5 arcseconds per second. 

The sliders that I see in the EQMOD window are for PulseGuiding (they go from 0.1x to 0.9x). The ST4 Guiding has drop down menu instead with fixed rates (0.25x 0.50x 0.75x 1.0x).

[swag72]

Thanks for that - I accept that the sidereal rate itself doesn't change, but you're saying that the default sidereal rate in EQMOD for pulse guiding is 0.5x, so the sliders give you 0.1-0.9x of this rate?

So say for example I wanted a pulse guide setting of 0.25 sidereal, then I'd be dialling x0.5 in the RA and DEC sliders? I don't use ST4, so that won't work for me.

Have I got that right?

[themos]

The sliders give you the indicated fraction of sidereal rate. If you want 0.25x sidereal, you will set them somewhere between 0.2x and 0.3x  indicated. 

[Gina]

Those sliders do work with EQMOD guiding - I used them when I was using a very short FL (200mm) on the guide camera as PHD would move the image enough with the default settings to calibrate.

[swag72]

The sliders give you the indicated fraction of sidereal rate. If you want 0.25x sidereal, you will set them somewhere between 0.2x and 0.3x  indicated. 

Thanks!

[swag72]

Those sliders do work with EQMOD guiding - I used them when I was using a very short FL (200mm) on the guide camera as PHD would move the image enough with the default settings to calibrate.

Are you saying that the ST4 sliders where you can select sidereal works in Pulse guiding without the ST4 cable connection?

[themos]

There's no ST4 sliders! The "Autoguider Port (ST4) Guide Rate" control is a pair of drop down menus. The "ASCOM PulseGuide Settings" control is the one with the sliders (just under the labels RA Rate and DEC Rate, top right).

[swag72]

Woops, sorry, meant the ST4 menu! That has NO bearing on the pulse guide does it?

Thanks for the screen grab Themos!

[themos]

That's right, the ST4 controls have no bearing on pulse guiding.

[chrisshillito]

For the recent test release of EQMOD we have made guiding type a setup option and so now only display the guiding control relevant to your chosen type - just to remove this kind of confusion.

The guide rate is a just a speed specified with respect to sidereal rate. So if sidereal rate is roughly 15 arcsec/sec and you set a guide rate of X0.2 then during a RA guiding pulse the mount will be moving at either 18 srcsec/sec (sidereal+sidereal*0.2) or 12 arsec/sec (sidereal-sidereal*0.2) depending on guide direction. A guiding pulse to the DEC axis would move the mount at 3 arcsec /sec (sidereal*0.2) irrespective of direction.

Chris.

[swag72]

Chris can you just confirm then what guide rate on the sliders relates to 0.25x sidereal and 0.5x sidereal?

[chrisshillito]

The sliders set the amount by which the usual tracking rate (sidereal rate for RA axis and 0 for dec axis) will be adjusted. The unit are expressed as a multiplier of sidereal.

For the Dec axis the slider value is the rate at which a guiding pulse moves so x0.25 will move the dec axis at sidereal/4. For the RA axis the slider sets the amount by which normal sidereal tracking will be adjusted during a guiding pulse., so a x0.25 rate will result in a xis movement rate of either 1.25xsidereal or 0.75xsidereal depending of pulse direction.

Chris.

[swag72]

These figures scare me to death!! Can I just ask a really simple question.

If I want to guide at 0.25x sidereal, what do I set the sliders to?

If I want to guide at 0.5x sidereal, what do I set the sliders to?

Sorry, this whole thing has gone well over my head now

[Merlin66]

Sara,

In the words of the Hitchhikers Guide "Don't Panic"

Set the ASCOM Pulse Guide Setting to show a tick in both the RA and Dec boxes and set the display to x0.25 for guiding at x0.25 Siderial rate, or x0.5 for guiding at x0.5 Siderial.

That's it.......

[swag72]

Sara,

In the words of the Hitchhikers Guide "Don't Panic"

Set the ASCOM Pulse Guide Setting to show a tick in both the RA and Dec boxes and set the display to x0.25 for guiding at x0.25 Siderial rate, or x0.5 for guiding at x0.5 Siderial.

That's it.......

In the screen grab that Themos supplied (same as my screen) where's the x0.25 and x0.5 setting? The only one I can see is on the ST4 menu and that doesn't work on pulse guiding.

[chrisshillito]

These figures scare me to death!! Can I just ask a really simple question.

If I want to guide at 0.25x sidereal, what do I set the sliders to?

If I want to guide at 0.5x sidereal, what do I set the sliders to?

Sorry, this whole thing has gone well over my head now

Just set the sliders to whatever rate you want. The lower the number the more gentle the correction, higher numbers give a more agressive correction. Start in the middle and see how you go.

Chris.

[chrisshillito]

In the screen grab that Themos supplied (same as my screen) where's the x0.25 and x0.5 setting? The only one I can see is on the ST4 menu and that doesn't work on pulse guiding.

Pulse guiding setup has two sliders that set the rate for RA and DEC in increments of 0.1xsidereal and with a range of x0.1 to x0.9. So for pulse guiding you cannot actually set x0.25 but can set x0.2 or x0.3!

Chris.

[Merlin66]

Sara,

If you look at the screen dump, you'll se a section headed ASCOM Pluse guide Settings over on the top right hand side.

There's tick boxes for both the RA/Dec and as stated above by Chris the numbers shown can be set to x0.2/x0.3 to give approx x0.25 Siderial guiding ( or set to x0.5 to give x0.5 Siderial guiding.)

Hope this helps.....

[swag72]

Thanks all

[Gina]

Just above the ST4 at the top right of the expanded view.