HEQ5 guiding problems

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Jovax
Posts: 12
Joined: Wed Dec 19, 2018 7:14 pm

Re: HEQ5 guiding problems

Post by Jovax » Fri Jun 14, 2019 3:13 am

Dear Chen

Thks for the support, yes. I have a backup os SD card
I just try the Beta app, and the PA is only possible if you can see the polar star, I'm in North but only possible to face south and I do polar aliment using another stars, close to the meridian
About the guiding I will try using with the ST-4 , I just using my asi120mm usb direct to asiair like I do with phd2 on PC, maybe is the problem,

PS:.bug - on last update 1,1, the preview became very slow, ex: on a 1 sec expose takes about 5 sec to get the preview and same times more, in the pass was very fast,
And the image histogram is very slow

Regards Jovax

lancer jiang
Posts: 74
Joined: Mon Nov 26, 2018 9:59 am

Re: HEQ5 guiding problems

Post by lancer jiang » Fri Jun 14, 2019 6:49 am

Hi Jovax:

The polar star is not necessary and you can verify this by some other ways to do the PA and contrast the accuracy of result.
We have tested PA on HEQ5_Pro,the guiding is much perfect than before.

Additional:
The "slowly preview“ was fixed in 1.2 test version

Jovax
Posts: 12
Joined: Wed Dec 19, 2018 7:14 pm

Re: HEQ5 guiding problems

Post by Jovax » Fri Jun 14, 2019 11:02 am

Hi

I try PA with asiair, and receive a notification ( I was more 30% away from NCP), the mount was 2 star align and polar align to face South, and was face to the meridian and close to the celestial equator,
For me dint work!..

Regards Jovax

W7AY
Posts: 54
Joined: Fri Jan 25, 2019 3:38 am

Re: HEQ5 guiding problems

Post by W7AY » Sat Jun 15, 2019 1:18 pm

Dear jovax,

If you were really pointed close to the celestial equator, you are about 90 degrees away from both poles, irrespective of the hour angle (meridian or not)! The notification that you received from the app is correct.

ZWO's specs asks for no more than 30 degrees from a pole.

- chen

Jovax
Posts: 12
Joined: Wed Dec 19, 2018 7:14 pm

Re: HEQ5 guiding problems

Post by Jovax » Mon Jun 17, 2019 9:32 pm

Hi Chen

OK, I will test again and I get back to you
Thks

Regards Jovax

W7AY
Posts: 54
Joined: Fri Jan 25, 2019 3:38 am

Re: HEQ5 guiding problems

Post by W7AY » Tue Jun 18, 2019 12:27 am

Dear jovax,

I don't know what algorithm ZWO uses (I am just a customer in the USA), but from the fact that they have not yet allowed anything further than 30 degrees from the pole may point to the fact that the accuracy might depend on the secant of the angle to the nearest pole.

Because of that, I would recommend that you get as close as you can to the pole as possible, even if they allow you to be off by 30 degrees. You just need an unobstructed FOV at the initial step and again after it has done the rotation. I think the FOV can even be completely obstructed in between those two ends, by tree branches, etc.

Perhaps Messrs. Ji and Jiang will be allowed to give us more detail.

For "blind" setup in an unfamiliar setting, I recommend starting with Polar Scope Align Pro (PS Align Pro) in iOS in its "Daytime/No Polarscope Alignment" mode to get you within a few degrees of the pole using the simple magetometer on iPads and iPhones.

- chen

Jovax
Posts: 12
Joined: Wed Dec 19, 2018 7:14 pm

Re: HEQ5 guiding problems

Post by Jovax » Fri Jul 26, 2019 11:42 am

Hi

I just update yesterday for last firmware and now I'm guiding much better! The PA is not working for me, always I try close to the south pole I get the same replay ( need to be 30% from the NCP). There's any way to do PA facing south? Im in North hemisphere but only possible to facing south hemisphere and I try already close to the meridian and low as 10%,20%,30% 40% etc and simple don't work. Or asiair PA don't work facing south only facing norte NCP?
Regards John

W7AY
Posts: 54
Joined: Fri Jan 25, 2019 3:38 am

Re: HEQ5 guiding problems

Post by W7AY » Fri Jul 26, 2019 4:48 pm

Hi John,

I assume that although you are in the northern hemisphere, that you prefer to use the southern stars for polar alignment?

I am too far north to try using southern stars, but you need to make sure that an unobstructed FOV is available both at the start and at the end of the 60 degree slew. It does not matter if the FOV is obstructed in between those two ends.

You may have to start not at the meridian, but tilted 30 degrees to one side, so that the the end of the 60 degree slew, you are approximately 30 degrees on the other side of the meridian.

The other thing to try (and I have tried this) is to initially disconnect the telescope (select None in he Telescope Setup). When you start polar alignment, ASIAIR will ask if you wish to proceed without a mount -- confirm that you do.

ASIAIR will then ask you to manually slew by 60 degrees. You can use the mount's hand controller RA buttons.

The advantage vs the automatic way is that you can move the mount by other than 60 degrees. The ASIAIR is looking for the center of rotation of the plate. It does not really care that the rotation is by 60 degrees or by 30 degrees, although the former will yield more accurate results than the latter.

Again, you do not have to start with the OTA pointed at the meridian. Pick two endpoints where the FOV is unobstructed (a small obstruction like branches obstructing a few stars is not a problem -- most plate solving algorithms will resolve the center of the plate -- see astrometry.net).

I.e., if you cannot see the north with 60 degree rotation, try going manually and rotate by either more or less than 60 degrees. I would not recommend any angle less than 20 degrees, especially if the telescope does not provide a flat field.

If the ASIAIR algorithm is doing the right thing, it should depend on the plate to determine the star locations, and not the mount's RA and DEC -- this is why you can do PA without connecting the mount to the RA. As long as ASIAIR knows your latitude and the local sidereal time, it should be able to determine the altitude of the stars and apply the correct atmospheric refraction corrections; it should not have to depend on the mounts's RA and DEC.

So, try starting away from the meridian, and also try to use manual slewing with an angle that is different from 60 degrees. The key is that you need two FOV that are unobstructed. The two FOV also need to be within 30 degrees of the closest pole.

The success of the PoleMaster is partly because it depends on the human to do the plate solving (matching the template of the polar stars). Because of that, you are forced to find two unobstructed FOV visually. There is no visual clue from the ASIAIR PA process. Perhaps one day they can replace the pictures of telescopes and fireworks with an actual FOV of the camera's image (what SharpCap does).

Good luck,
Chen

W7AY
Posts: 54
Joined: Fri Jan 25, 2019 3:38 am

Re: HEQ5 guiding problems

Post by W7AY » Fri Jul 26, 2019 7:03 pm

Hi John,

You also need to check with ZWO if the ASIAIR is using your latitude to select whether to use the northern stars or the southern stars while plate solving during polar alignment.

If it is using only a database of northern stars when you are in the northern hemisphere, it will be impossible to use the southern stars to polar align, even if you meet other parameters.

However, by using non-zero initial offsets from the meridian that I described, you might still be able to see enough northern stars to use the stars at the north.

If not, drift alignment using PHD2 may be your only option. There are some mounts that can correct for polar alignment error after performing multiple star alignments.

Good luck,
Chen

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