Guiding on 2nd plan target - Forums

Topic starter

Oct 23, 2023 · Edited: Oct 23, 2023

I set up a plan last night; first the Bubble Nebula and then, once it hid behind some trees, the Spaghetti Nebula.

The guiding was fine for the Bubble Nebula, but once the scope moved on to the Spaghetti Nebula (at 02:09), it all went a bit wrong, with long streaks UNTIL a meridian flip was performed, then all was fine again.

I've had this last time I ran a Plan too, but in the past it's all worked fine.

Is there anything obvious I'm missing? Is there a setting to recalibrate for a new target?

Here's the log.

Autorun_Log_2023-10-22_202314 (1).txt

Thanks!

PS - the issues with the last few frames of the first target were because it had moved behind a tree. Perhaps this threw everything off with the 2nd target?

Johannes Maximilian Möslein

Oct 23, 2023

You should recalibrate guiding when your Setup flips, and looking at Stellarium, the Bubble and Spaghetti are on opposite sides of the Meridian. Calibration of the guiding tells the program everything about orientation, balance, direction and so on, so if you don't do that, it will just be wrong if you reuse it for different targets.

Additionally, the log after 2:09 has many instances where you either lost the guide star, it didn't even find one or the settling failed, which confirms the problem. If it was fine after the Meridian flip after that, than calibration was probably the only problem.

I don't know which program you are using, but it should have an option to recalibrate when slewing to a new target, that should fix it.

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Piers Palmer

Topic starter

Oct 23, 2023

Thanks Johannes,

I'm using ASIair and I just can't seen an option anywhere to recalibrate for a new target. It must be in there somewhere!

You've confirmed what I thought I should do anyway.

Frank Alvaro

Oct 23, 2023 · Edited: Oct 23, 2023

I've used the ASIAir for a few years now, shooting many multi-target plans over the space of a single night, and have never experienced a problem that I feel was related to guiding having changed due to moving to a new target. At the start of each session I polar align to an accuracy of less than 10 arc seconds, then slew the scope to the meridian and just south of the celestial equator (I'm in the southern hemisphere) before calibrating the guiding. Once that's done the plan is started and it's off to watch TV or to bed, letting the plan do its thing. This is not to say that problems don't occur (autofocusser went haywire last night) but generally things work as expected.

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Piers Palmer

Topic starter

Oct 23, 2023

Thanks Frank - I wonder if that's my problem. As Johannes pointed out, my two targets were pretty widely spaced and my initial guiding was calibrated on my first target. Next time I shall try calibrating as you do, around the equator at the meridian. I'd forgotten about that!

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Quinn Groessl

IOTD Staff

Oct 23, 2023

What mount do you have? Also, in the settings, do you have restore calibration on or off, and do you have recalibrate after AMF on or off?

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Piers Palmer

Topic starter

Oct 23, 2023

Hi - I've got a Vixen SXD2 mount and I have restore calibration set to off but after a meridian flip it's set to on.

Quinn Groessl

IOTD Staff

Oct 23, 2023

Piers Palmer:
Hi - I've got a Vixen SXD2 mount and I have restore calibration set to off but after a meridian flip it's set to on.

Okay, I don't know much about that mount, I only ask because the way this behaves can be different from the depending on manufacturer. Those are what I was going to tell you to try in the settings anyway. Sorry I'm not much help.

Jerry Gerber

Frequent contributor

Oct 23, 2023

Piers Palmer:
Thanks Johannes,

I'm using ASIair and I just can't seen an option anywhere to recalibrate for a new target. It must be in there somewhere!

You've confirmed what I thought I should do anyway.

I also use ASIAIR Plus and after the meridian flip it automatically begins the calibration routine before resuming imaging. . Did you manually do the flip or did you automate the process?

Other than watching the flip in case of cable snags I let it do everything automatically. Sometimes the go to fails to target the object precisely, but often it works fine.

Jerry

Chris Ashford

Oct 24, 2023

Maybe guiding after a meridian flip is mount dependent but I almost never have problems guiding after a meridian flip. (I'm using ZWO's AM5 mount). When I do it usually because a cable has snagged on something after the flip. I often image multiple targets in a single session - I look out for big azimuth changes between targets and double check the cabling to make sure that the scope is going to swing freely in the middle of the night while I'm asleep

I did have a problem last week where my guiding kept failing, just like your log Piers. The reason was that I forgot to adjust my guide scope settings - the previous week I'd been out at a Bortle 2 site and was guiding at 0.5s intervals with a gain on 60 on an ASI120MM. Then I come back home to Bortle 7 skies and here I guide at 1s or even 2s intervals with gain adjusted accordingly. Are you sure there wasn't a degradation of seeing, or transparency, or some high level cloud that came through in the early hours of the morning?

BTW I'm not aware of a way to automatically recalibrate - I think you must manually clear calibration to force recalibration on the next guide. Calibration needs to be done close to the celestial equator, which requires you to choose a calibration target too.

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Piers Palmer

Topic starter

Oct 25, 2023 · Edited: Oct 25, 2023

Hi - It seems I don't have any problem guiding after the meridian flip either!

If anything my transparency improved for the 2nd target with the 7day old Moon having set, and judging by the frames (and the thermometer) there was no hint of cloud all night.

I think next clear night, particularly if it's a full Moon, I'll calibrate as recommended on something near the equator on the meridian, and then set a plan for several targets to see if it makes a difference.

voigtm

Oct 25, 2023 · Edited: Oct 25, 2023

I use an ASIAir Plus with a GEM45 and haven't had any guiding issues doing multiple targets during a session. Since I don't have access to anything close to the meridian+equator (trees), I usually calibrate about 25 degrees above the equator and just east of the meridian.

However, if I remember correctly, if you go to Telescope>Meridian_Flip> there is a switch for engaging re-calibration after flip. I'm not near my set up at the moment so I can't check to be sure, but I do remember seeing that option (at least in earlier versions of ASIAir). I don't know if it will recalibrate if you move to a new target that's on the opposite side of the meridian (which requires a flip)

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