PHD2.6.9dev2 released

[Jonk]

Not sure but isn’t the blue target an option in the crosshairs? Just a guess without switching a pc on...

Also, 2 seconds might be too quick, try 4 or 5 seconds without saturating stars and you may find it improves things?

[kens]

The blue target thing is a bookmark. You can clear it in the Bookmarks menu

[tooth_dr]

3 hours ago, Jonk said:

Also, 2 seconds might be too quick, try 4 or 5 seconds without saturating stars and you may find it improves things?

I’ve never really persisted with longer times, the brief time I tried it it seemed worse 🤷‍♂️ 

0.6” is ok for me though. 

[tooth_dr]

7 minutes ago, kens said:

The blue target thing is a bookmark. You can clear it in the Bookmarks menu

Thanks Ken.

[Jonk]

Just tried the blue target thing, yes it's a bookmark so good to know if I ever see it!

I've also just started a run with the az-eq6 and oag, with multi star on and after 1 worm rev (8 minutes) I'm showing steady seeing and 0.77" RMS. As you can see, it was brilliant for 2 minutes, then a bit choppy for 4 or so minutes.

Conditions + 'cheap' mount mechanics, so no surprise really.

But it's of no real consequence to me for this setup really, as I'm imaging at 3.2"pp anyway!

The mount needs to be stripped and tuned at some point, so that may improve things.

[Jonk]

After as 30 minute sub, it slewed to the next panel in this particular mosaic, and the guiding result over 1 worm revoultion is completely different and much cleaner.

I guess what I'm trying to say is don't worry about the nitty gritty as there's too much outside of our control!

[tooth_dr]

10 hours ago, Jonk said:

After as 30 minute sub, it slewed to the next panel in this particular mosaic, and the guiding result over 1 worm revoultion is completely different and much cleaner.

I guess what I'm trying to say is don't worry about the nitty gritty as there's too much outside of our control!

Just an observation - the graph the RA RMS is reporting 0.60” which is fantastic. But it is oscillating between almost +2 and -2 arcsec.  I appreciate your imaging scale is large but does this mean RMS isn’t really a good comparison mechanism?

[Jonk]

The peaks in this particular case might be +-2", but given I don't have PEC applied, that's ok.

The RMS value is a function of RA and DEC errors, so remove those couple of peaks, the RMS will likely be only a fraction lower.

People have often mentioned that the graph itself is not the only thing to rely on - no-one wil have a flat graph in reality, but the RMS value is probably the most reliable bit of info to use, coupled with knowing what's going on elsewhere (seeing, pixel scales etc).

Understanding why things are doing what they are is more important than just looing at a grpah and saying hey, it's perfect. Which I suppose is ironic as the program started out as push here dummy and you weren't expected to know what was going on.

Here's part of the 30 minute ha sub that this guiding produced (stf and screen grab at 1:1, little bit of tilt to sort out)- no surprise really given the imaging scale.

Moral of the story, if the results look good (remembering that round stars does not mean good guiding) and we have a vague understanding of what it's doing, therefore pointing towards improvements that need to be made, then all is well. Does multi star improve guiding? I don't know, but it appears to in the numbers displayed.

Edited January 7, 2021 by Jonk

[tooth_dr]

1 hour ago, Jonk said:

The peaks in this particular case might be +-2", but given I don't have PEC applied, that's ok.

Thanks Jon for the reply 👍🏻

Its not what I understood to be PE, but the jumps in RA 2" in either direction from baseline.

1 hour ago, Jonk said:

RMS value is a function of RA and DEC errors, so remove those couple of peaks, the RMS will likely be only a fraction lower.

 

I suppose this is my point. You can have big peaks that would impact on the image but still have what appears on paper to be a good RMS value.

To be honest I'm not what my point is, just trying to consolidate my own phd2 results with others.  I've a good idea what's going on with my kit and now thinking how much is due to seeing.

[Jonk]

Seeing is a huge part of it, but even moving the mount by say 1 FOV width for the next mosaic panel, the results instantly change - you can see that by the star mass graph after what PHD thought was a dither command.

44 minutes ago, tooth_dr said:

Its not what I understood to be PE, but the jumps in RA 2" in either direction from baseline.

Ok, I see what you mean - this could not be explained with any guarantee - it could be seeing, it could be mechanical (more likely), contrail, it could have been a bird or something across the guiding FOV even. If you're getting good results, and when you get bad results you can do something given the information to improve those results, largely the numbers / graphs are not definitive.

A key point I guess is to match or better your guiding scale to your imaging scale and understand what improvements you can make, and what is outside of your control.

Do I remember you having a Mesu? How's it doing gerenally?

[tooth_dr]

47 minutes ago, Jonk said:

Do I remember you having a Mesu? How's it doing gerenally?

Yes I do, I sent you a copy of the Mesu handbook March last year 😂

The mesu is working great, it has around 30kg payload on it, and consistently guides well, and platesolving takes two goes to get within 2-3 pixels of the target.