kens

8 hours ago, michael8554 said:

If you must use sub1 second exposures, use the PHD2 MultiStar mode, which compensates for "Chasing the Seeing".

And/or use the Z-filter algorithm which lets you adjust the guiding response as a multiple of the exposure time (or, more correctly, a multiple of the sampling rate). But it is best suited to mounts that can make small, precise corrections.

PHD2 operates the ZWO cameras in single shot mode rather than in video mode. The single shot mode has a latency per shot of a few hundred milliseconds (up to 500 from memory). This is a function of the hardware and ZWO driver. So if you choose a 1s exposure then the time between shots is going to be 1.5 seconds. On top of that you add the time taken to make corrections as you dont want to take a guide image while the mount is moving (and probably why single shot mode is used) and any download time. In my setup I can just get a 1s sampling rate if I choose an exposure time of 0.5 seonds.

Avalon make a guide scope extender but its a bit pricey

https://www.avalon-instruments.com/products-menu/accessories/extender-for-finder-guide-scope-detail

One possibility: As you know the PA error can be broken down into an Alt and Az related component with the Alt component dominating near the horizon and the Az compnent dominating near the meridian. If one causes drift south and the other north then in between there is a crossover point where there is little or not drift. With the mount rotating you will encounter that point somewhere during the evening.

Also tell us where your scope was pointing when you di the calibration. If it was in the home position pointing near the pole then you wont get enough movement in RA for the calibration to work.

You should also try the manual guiding tool to check that the mount is actually responding to guide commands. To do this, point near the celestial equator and select a star. Then choose the Manual Guide option on the Tools menu. Use the maximum pulse duration (5000 ms) and click the west button. You should see the star move steadily on the screen for 5 seconds. Click East and you should see it move the other way for 5 seconds.

4 hours ago, Jonny_H said:

I have recently changed my kit so that i can utilize NINA, PHD2 etc... mainly to free me from the ZWO bubble that the ASIAir restricts you to,  but also to open software capabilities. So next time I get out (whenever this weather decides to give it a rest) and have a play.

Just FYI, the ASIAir is basically a Raspberry Pi and you can install Astroberry, StellarMate or a DIY INDI/Ekos/KStars onto it. These are open source are not restricted to ZWO hardware and there is even an INDI driver that lets you continue to use the ASIAir power ports. Plus you get the fulll blown versions if these and PHD2 rather than the de-featured versions implemented by ZWO.

Have you got PHDLogViewer installed? If not you can download it https://adgsoftware.com/phd2utils/

The first thing I noticed is that your guide rates are set at the EQMOD defualt of 0.1x sidereal (or 1.5"/s) which is way too slow. Incerase the guide rate to somewhere between 0.5x and 0.9x sidereal. You will need to recalculate the calibration step size as a result.

The other thing to check is the focal length of your guide scope. It has been entered as 50mm but I think that is the aperture, not the focal length. As a result, your guide RMS in arcseconds would be way off. The guiding RMS of 0.3 pixels is quite reasonable.

Overall, I would suggest that you sort out the guide rate and guide scope focal length and create a new profile in PHD2 with the wizard. Then try again.

3 hours ago, wimvb said:

With a longer fl scope and the same camera (pixel size) the angle/pixel will be smaller, so the arc secs RMS will be smaller too. But only by 10% in this case.

Quite right. Should have had my morning coffee before responding 😬

Then I'd suggest to use the profile wizard to create a new profile. When it is finished check the calibration step size on the Guiding tab of the brain. It should be around 400ms for  a target around dec 0. In the calculatoryou need to enter the declination for each target as that adjusts the step size accordingly. 

Well I guess now, nobody is going to be game to recommend a HEQ5 to this guy  🤣

It wont make any difference in your images. PHD2 works on pixel measurements and the focal length is only used to convert that to arcseconds for display purposes. Increasing the focal length value will make your guiding appear worse (assuming identical circumstances) as the longer length translates the pixel RMS value to a larger displayed arcsecond RMS value

Your problem looks more like dec backlash.

Your calibration is also not great. Did you calibrate on your target? The rates indicate not but that could be due to any number of things. The dec rate vs RA rate indicate calibration at a declination of around 33 degrees

A good calibration is essential for guiding. Yours is orthogonal (good) but based on only a few data points. Ideally you want about 10-15 points along each leg. That is determined mainly by the calibration step size. If you use the profile wizard to set things up it normally calculates the step size correctly as long as you input the correct guide rate. If you didn't use the wizerd then set up a new profile using it and try again. Otherwise, recalculate the step size in the brain. You should be using a step size of around 400ms (vs 1200ms) to get a reaonable number of calibration steps.

A reasonably good polar alignment is also needed for calibration but I don't see the telltale signs of very poor polar alignment in your calibration (a vee shaped RA calibration leg). Since you have both Astroberry and PHD2 you can ditch the polar scope and use any of the excellent PA methods in those tools. As a starter I'd suggest using the Polar Drift Alignment (PDA) in PHD2 as it is quick and easy. The EKOS PA too in Astroberry is also very good and more accurate but a little more involved. Both are easier and more accurate than using a polar scope and do not rely on a good calibration to work.

After you calibrate then run the PHD2 Guiding Assistant including the backlash measurement. That will tell you more about what is going on.

Could it be due to misting of the sensor cover? Would that behave like a giant dust mote?

You may need to turn on debugging and capture the full logs for both camera and focuser. 

On your screen shot the message says "image received" which means an image was acquired - at least when you did your screen shot

And tangentially, why is the focuser reporting a temperature of 33C in Canada in winter!

10 hours ago, ItsRiftzy said:

So have I been using the wrong set of numbers on the circle? Because I've been using the bottom set of numbers (furthest away from the pointer) is that correct for the Southern Hemisphere?

Its so long since I used setting circles that I forget. And it might depend on the type of mount. But use whatever gives the right result. Namely, if you rotate the mount from east to west the pointer mark should point at decreasing RA values. 

Note that if you use the HA technique, that HA increases from east to west.

At dec 0 the mount moves the maximum distance for a given guide pulse - as measured on the sensor. Conversely, at the pole there is no visible RA movement no matter how big the guide pulse.

When you reuse your calibration at different declinations the RA pulses are scaled according to where the calibration was done. By calibrating near dec 0 you get the most accurate scaling.

You can of course calibrate on every target but reusing your calibrations can save a lot of time.

3 hours ago, ItsRiftzy said:

Hey there,

I simply just point at Sirius or another bright star, check to make sure DEC is correct (if not I'll polar align again). Then adjust the RA circle so it matches Sirius (6h45m), this method should work well but strangely M42 is higher in the sky than Sirius from my perspective but is 1hr lower than Sirius. I'm not sure what I'm doing wrong here. I don't know if I'm using the RA circle wrong.

That's correct - RA decreases as you move west. Try using the other set of numbers on the setting circle.

On 16/01/2022 at 12:24, ItsRiftzy said:

3. Calibrate RA with Sirius by moving the circle to 6h45m

Out of interest, how do you do this calibration?

Also, one problem with setting circles is that you need to recalibrate through the night. Another method is to use the setting circles for Hour Angle where 12:00 is overhead, 06:00 is due west and 18:00 is due east. When your scope is in the home position (for the southern hemisphere it is aligned to both 06:00 if you move right in declination and 18:00 if you move left. So that's the only choice you need to make when calibrating i.e. are you going to be looking east or west. If east then movve the setting circle so that the pointer is on 18:00 and if west move it so that th epointer is on 06:00. When looking for targeets, just about every planetarium application can give you the hour angle at a given time.

As mentioned the setting circles are not very accurate but they should get you close enough to find you taget with the finder scope.

I'm very happy with my Aaeon-UP Core. https://up-shop.org/up-core-series.html.

The newer model is the Core Plus https://up-shop.org/up-core-plus-series.html

I'd recommend buying with the Alu case as I had to bodge one together. You will also need an external antenna.

It is very reliable, much more so than  my RPi3. I've had it since mid-2018 and it hasn't missed a beat whereas the RPi intermittently stops running after a couple of hours. I installed Ubuntu on the Aaeon but it is an x64 CPU so you can install Windows on it. But I think Linux is better supported on it. 

As far as I know you can set up Windows to run as a hotspot https://support.microsoft.com/en-us/windows/use-your-windows-pc-as-a-mobile-hotspot-c89b0fad-72d5-41e8-f7ea-406ad9036b85#WindowsVersion=Windows_11

It looks like the registration stage has failed. Maybe you need to put in some registration options like Min Star Pairs

Just guessing

Also, try to stick with 2 second exposures. 1 second guiding exposures wont really help you.

I'm a bit suspicious of the normalised guide rates: Ra 17.2 and Dec 15.6 when 13.5 is expected.

Make sure you are tracking at sidereal rate and that the controller knows you have a EQ6R

Please post your PHD2 guide log.

Also, what kind of mount are you using?

6 minutes ago, teoria_del_big_bang said:

I think @kens has hit the nail on the head.
But why it does not show the same effect at faster frame rates I am not sure, maybe it just calibrates much faster and so you do not see the effect so much in the final image as there is more exposure when guiding correctly.

Steve

 

I suspect you are right and it is just that the calibration goes much faster. The good news is that it looks like a good, orthogonal calibration

Those start trails look remakably like what you would get if PHD2 was calibrating while you were imaging. With ST4 guiding you calibrate on each target so you need to let the claibration complete before starting imaging.

Another possible reason for poor guiding with the longer guide expsoures is that ht e guide star is saturated. Use the star profile view to check that and if the profile has a flat top, reduce the gain on your camera.

If you can attach your guide log that would be helpful to analyse.

I doubt PPEC would work on such a short period. Targetted PPEC is often recommended for PE in the 100 to 200 second range. In this case it could be used to attenuate the 122 s period although it is not too bad at 0.2" RMS compared to the 0.6" RMS of the 13.6s period.

The problem is that it is not caused by just one tooth - its every tooth mesh and it is across three gears. And given that they are not in whole number ratios then you would expect every combination of tooth to tooth to come about during normal rotation.

This article shows how the belt mod can help: https://www.amateurastrophotography.com/heq5-pro-belt-improvement-1

You replace two points of tooth contact with a belt that engages multiple teeth on each gear.

Here is a graphic illustrating the tooth mesh: http://www-mdp.eng.cam.ac.uk/web/library/enginfo/textbooks_dvd_only/DAN/gears/meshing/gearAnimation.gif

If one tooth disengages before the next one engages you get this kind of periodic error