PEC & EQMod problem?

[blinky]

I finally got round to gathering some data for PEC with EQMod tonight. I used the ZS66 and the Meade DSI and gathered the data with PHD. The thing that is puzzling me is that according to PECPrep my average +PE is 0.27 arc Secs and -PE is -0.17 arc Secs. I just cannot see how my HEQ5 Pro has that small a PEC????? Should I gather the data again with the 8" SCT and see if I can get some better data?

[chrisshillito]

Did you makes sure guiding output was disabled from PHD?

Capturing your PE with a a longer focal length will give better analysis but you may find problems with PHD stopping loging if the star drifts outside of PHDs 50 pixel search area. If recoding for PEC you ideally need 5 worm cycles worth of data and keeping the star in the box for that length of time at higher focal lengths (with possible polar alignment drift) can be difficult.

Chris.

[blinky]

Id1ot Syndrome tonight Chris - I left guiding on, although I did RTFM I obviously never read it and understood it!

Will try again next time it's clear - January maybe....

[chrisshillito]

Oh well you'll be using PECPrep to analyse your guiding performance then :-)

... seriously it can be interesting to see if there are any of the "significant mount frequencies" still present in the guided signal.

Chris.

[blinky]

It did pick up one frequency that was the worm gear I think..... I will have another go next time, just hope my polar alignment is good enough to go 40mins unguided in a 50 pixel box.....

[ncjunk]

Let us know how you get on, I am planning on doing mine the next clear spell. It is very frustrating here as there are clear spells interspersed with heavy showers so I can´t risk imaging at the mo...doesn´t look very promising in the Atlantic either.

[steppenwolf]

I have done this with my EQ6 but not using PHD so I have a larger sample area and I am very encouraged by the results so worth doing - I had a drift alignment in place to ensure a very accurate polar alignment.

[chrisshillito]

It did pick up one frequency that was the worm gear I think..... I will have another go next time, just hope my polar alignment is good enough to go 40mins unguided in a 50 pixel box.....

Yes, that's the rub with PHD although in theory you could guide in declination and not disturb the PE data. If you have a webcam to hand perecorder is the best option. There are methods to use K3CCDTools, Maxim, Metaguide, Guidemaster, CCDsoft and Astroart logs should those applications support your camera type.

Chris.