comet tracking

[Malcolm Park]

Hello, 

since my mount cannot track directly on comets, I understand it may be an option to guide on a comet. 

Has anyone done this with PHD2 and if so any steps to recommend? 

thanks,

Malcolm

[Brian Valente]

Malcolm

The documentation is a really good place to start

https://openphdguiding.org/man/Tools.htm#Comet_Tracking

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Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

[Malcolm Park]

I managed to get it going 

Ths is a single 5 minute exposure with a short refactor at 1.8"/px imaging scale, ZWO 2600mc duo.

I expected smooth streaks, but this is evidence of something not right.

Everything looked right in the setup. 

The tracking rate values were populated in PHD2 via the connection to CdC.

PHD2 appears to have tried. Any suggestions on how to tweak PHD2 to get smooth star streaks?

Let me know if I can add any more capture or setting details for analysis, 

thx,

Malcolm 

[Malcolm Park]

[Brian Valente]

Malcolm

the rates are supplied by CdC, so that's where i'd start. PHD can only operate on the rates provided, if the rates aren't correct, it can't really do much there. 

FYI when you comet track, the guide graph will look terrible, FYI. It's possible to smooth it out by also applying a custom tracking rate to your mount, but since that's not an option for you, it's not a realistic expectation that you will get "normal looking" guiding

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/24c296ca-2fcc-4e08-8b07-0c6ec2da59c0n%40googlegroups.com.

[Brian Valente]

PS - you sample image just came across - that doesn't really look like a guiding rate issue, it looks like it jumped

Please provide your logs

[Malcolm Park]

I think it uploaded ok

https://openphdguiding.org/logs/dl/PHD2_logs_HBas.zip

[Brian Valente]

Malcolm

That looks like pretty standard comet-tracking results. it's not pretty but it should work. 

btw it looks like you are using a 10micron mount, I would be surprised if it doesn't support variable rate tracking. are you sure it doesn't do this?

Also I suggest disabling dither for comet tracking.

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/f37c03ca-b745-4d3a-9147-76676a02beddn%40googlegroups.com.

[Malcolm Park]

yes but keeping a long story short, I thought I would give PHD2 a go. 

thanks for the feedback, much appreciated.

cheers

Malcolm 

[Brian Valente]

Okay well PHD seems to be doing its job as it is asked. As i mentioned before, comet tracking results look pretty rough compared with normal sidereal, but your overall RMS is still good for this.

Usually if you are going for comet tracking and want ideal results, the first choice is rate changes in the mount, then comet tracking guiding, and if you want to give it both barrels you would do both custom tracking in the mount and comet tracked guiding.

Another possibility is you can just shoot sidereal and use shorter exposures. 

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/86ec8d32-2dee-49b4-a3c2-3dfeaff93ef7n%40googlegroups.com.

[Malcolm Park]

good to know, thanks for the ideas!

Malcolm