HEQ5 Guide Tracking Speed?

[Interested]

Hi All,

Well, I am now all setup to try some guided imaging (just waiting for a clear night!!) but can someone explain "Auto Guide Speed" to me - what it should be set at and, why?

I would have thought if I was imaging DSO's then 'Tracking' should be set at sidereal rate and 'Auto Guide Speed' should be set at 1x, but this probably not the case?

Do 'Tracking' & 'Guide Speed' work independently to each other?

Thanks for any help

[steppenwolf]

Tracking (sidereal) and Guide Speed work independently from one another. Keep sidereal set as is but experiment with guide speed as no 'one size fits all 'but start at 0.5X and experiment with that and the 'aggressiveness' setting in your guiding software to find which combination works best.

[Interested]

Thanks Steve,

It seemed sensible to me that 'Guide Speed' was the speed at which 'errors' (movement away from the guide star?) would be corrected but, it also seemed sensible to ask!

Again, many thanks.

I have another question now on using PHD but I will start a new topic for that....

[chrisshillito]

If you had a perfect mount, perfectly aligned then you wouldn't need guiding and the mount tracking at sidereal rate would keep your object perfect centred on your imaging device. In the real world however there are many factors that act to cause an object to "move" with respect to a mount tracing at sidereal. For a guide system to correct this movement it must therefore move the mount at a variable rate that is either faster or slower than sidereal.

The guide rate specifies how much faster or slower the mount will move with respect to sidereal whenever a guiding pulse is present. X1 would mean a correction of 1xsidereal (so doubling of sidereal rate in one direction and effectively stopping tracking altogether in the other direction).

In practice you really shouldn't need such an aggressive correction rate as x1 but the rate you choose needs to be matched to your system. There is no right or wrong value but ideally you want the slowest rate that provides the guiding performance necessary for the target you are imaging. Try 0.25 X Sidereal to start with and see how the guiding performs - it it seem a little sluggish then increase it.

Chris.

[Interested]

Chris,

Thank for the clear explanation. I did search the topics, but couldn't find an answer to my question. I am sure it will be helpful to a lot of us 'newbies'.