PECPrep - PHD guiding data question.

[rharrison]

Hello,

So I got out last night with my new NEQ6 reasonably nice 300 second exposures.

I recorded the log data from PHD to build a pec corrections file with pec prep to use in EQASCOM/EQMOD

I left the mount running all night imaging until it got light hence it lost the guide star and did crazy corrections for a bit, should I delete the last 50 or so lines from the log ?

This is my first go and making some pec data.

Rob

PHD_log_26Apr15.txt

[Demonperformer]

I'm no expert, but I would be inclined to cut it off at about 6730, where you start to get all those zeroes at the end of the line. I think I'm right in saying that the NEQ6 requires about 48 minutes of PEC data.

[rharrison]

I've read 40 something mins too but I was under the impression the more data the better you can remove wind etcetera by averaging the cycles.

I think I need to learn the pec prep software more first just loaded the log file and... well it's not exactly intuitive to use lol

[chrisshillito]

Hello,

So I got out last night with my new NEQ6 reasonably nice 300 second exposures.

I recorded the log data from PHD to build a pec corrections file with pec prep to use in EQASCOM/EQMOD

I left the mount running all night imaging until it got light hence it lost the guide star and did crazy corrections for a bit, should I delete the last 50 or so lines from the log ?

This is my first go and making some pec data.

Rob

If you were imagaing then you were guiding? If so then the log isn't going to useful for PE analysis or PEC generation - though you can use it for guiding analysis. For PE and PEC you would need to use an unguided PHD log (and if you intend to generate a PEC curve you would also need to generate and apply a 'timestamp' )

If you want to capture PE and generate PEC whilst actively imaging then use the autopec feature of EQMOD rather than a PHD log. Details of how to use autopec can be found in the VS-PEC documentation  http://eq-mod.sourceforge.net/docs/eqmod_vs-pec.pdf

Chris.

[rharrison]

If you were imagaing then you were guiding? If so then the log isn't going to useful for PE analysis or PEC generation - though you can use it for guiding analysis. For PE and PEC you would need to use an unguided PHD log (and if you intend to generate a PEC curve you would also need to generate and apply a 'timestamp' )

If you want to capture PE and generate PEC whilst actively imaging then use the autopec feature of EQMOD rather than a PHD log. Details of how to use autopec can be found in the VS-PEC documentation  http://eq-mod.sourceforge.net/docs/eqmod_vs-pec.pdf

Chris.

Thanks Chris

At the risk of sounding like a moron what data would it record if it's not guiding ?

[kens]

An unguided trace records the deviation from an unguided perfectly tracked guide star. An unguided perfectly tracked unguided guide star gives you straight flat line on the graph. Any deviations are due to PE, misalignment, vibration, seeing etc...

PECPrep and its ilk let you filter out the noise from the PE.

[rharrison]

An unguided trace records the deviation from an unguided perfectly tracked guide star. An unguided perfectly tracked unguided guide star gives you straight flat line on the graph. Any deviations are due to PE, misalignment, vibration, seeing etc...

PECPrep and its ilk let you filter out the noise from the PE.

Thanks, sorry just a couple questions, so to get the data obviously connect the camera and mount in PHD. Do I have to do looping exposures ? do the calibration  ? Select a star? Or just literally connect camera and mount and check the 'log' option on tools. Couldn't find a tutorial or anything.

[kens]

Thanks, sorry just a couple questions, so to get the data obviously connect the camera and mount in PHD. Do I have to do looping exposures ? do the calibration  ? Select a star? Or just literally connect camera and mount and check the 'log' option on tools. Couldn't find a tutorial or anything.

Connect up as normal. You need to have a good calibration before starting so PHD can record RA and Dec accurately. Enable Guide Log under Tools (I always leave Guide Log enabled).

Select a guide star and set appropriate exposure and duration as you would for normal guiding. I use 1 second or 2 second duration

In the Brain dialogue under Mount tab uncheck Enable Guide Output so PHD doesn't send any guiding pulses.

Then start guiding.

It's best to only have one guiding session in your log file as PECPrep only picks up the last one in the file. Otherwise you need to edit the Guide Log.As far as I can tell the only way to get a new log file is to close PHD and open it again.