HEQ5 Pro initial slew

[martinclayden]

I've just received a new HEQ5 Pro and discovering it's capabilities.

After a reasonably accurate daytime PA (compass and inclinometer) and mount levelling, I find that the initial slew to an object is consistently off; to the West and South of the object.

I'm a bit uncertain of the setup parameters for time zone and DST - I'm in the UK and entered 0:00 and No respectively.

Has anybody any tips or observations about this please?

Will this resolve after a star alignment?

Thanks

Martin

 

[almcl]

There are two aspects to this.

First, daylight saving time or British Summer Time is in force at the moment, so your  DST should be "yes".  That may take out some of the error but possibly not all of it.

The second part is how accurately the home position is pointing at the pole. PA doesn't affect this, you need to make sure you are as close to the pole as possible looking through the eyepiece or finder when initialising the mount if you want the first goto to be accurate.

[Cornelius Varley]

2 hours ago, martinclayden said:

I'm a bit uncertain of the setup parameters for time zone and DST - I'm in the UK and entered 0:00 and No respectively.

DST should be YES until the clocks go back to GMT.

[Laurieast]

Put a meter long stick in the ground between where your southern tripod legs would go, stand by it at True Solar Noon , mark the spot to the north where the shadow of the stick is at noon. Draw a line on your paving or such, now you have a permenant true North/South line. 

Bin the compass 😉

 

Edited July 15, 2021 by Laurieast

[martinclayden]

1 hour ago, almcl said:

There are two aspects to this.

First, daylight saving time or British Summer Time is in force at the moment, so your  DST should be "yes".  That may take out some of the error but possibly not all of it.

The second part is how accurately the home position is pointing at the pole. PA doesn't affect this, you need to make sure you are as close to the pole as possible looking through the eyepiece or finder when initialising the mount if you want the first goto to be accurate.

OK - I'll set DST on next time.

I'm a bit confused about your second statement though; "as close to the pole as possible" - means Polar aligned I think ? If so, what's the relationship between "home position" and PA ?

Regards

 

Martin

[7170]

Have you done a star alignment through the menu?

If you haven't, the mount will be assuming the home position (and your scope) is perfectly aligned with the NCP when it starts, which it won't be in reality. If you have done a 1 star alignment for example and it is still out then there is something else going on.

[almcl]

2 hours ago, martinclayden said:

I'm a bit confused about your second statement though; "as close to the pole as possible" - means Polar aligned I think ? If so, what's the relationship between "home position" and PA ?

Polar Alignment is the act of pointing the mount's RA axis at the celestial pole.  This can be done without the telescope being on the mount and for purely visual use 'near enough' is quite sufficient to keep an object in view while the scope tracks.  This doesn't, however, mean that the scope will be pointing at the pole, a small displacement in either axis (which won't affect or be affected by PA at all) means that the first goto will be off, by at least as much as the scope was off from pointing at the pole.  There are other errors that can affect this, but the scope not pointing exactly at the pole when in the home position is quite a common one.

Hope that makes sense? 

[StevieDvd]

In most places the home position is stated as weights down pointing at the NCP (or SCP) but in reality it can be whatever you choose, as long as the mount knows what the co-ordinates and your scope is started at that position (and that your PA, date, time & locations are set properly). See this thread for some pointers in setting a mark for the 'standard' home position on an HEQ5.

I usually say to people not to trust the accuracy of their home position unless it's returned to that by the mount and is not moved manually. Setting it manually helps but you won't be exact like the mount expects, this is why the scope  normally expects to go through a 1 to 3 star alignment.

Before I stated using platesolving I used to start at my rough home position, do a goto and centre that by moving the scope manually (not with the handset), then any goto should be accurate enough for visual or non-guided sessions.

 

[martinclayden]

3 hours ago, 7170 said:

Have you done a star alignment through the menu?

If you haven't, the mount will be assuming the home position (and your scope) is perfectly aligned with the NCP when it starts, which it won't be in reality. If you have done a 1 star alignment for example and it is still out then there is something else going on.

No, not yet, still learning the ropes with the mount in daytime use

[martinclayden]

The consensus I'm hearing is that star alignment and good PA is needed for accurate Goto; I know that's kind of obvious, but I was hoping for a bit more accuracy based on just reasonable PA. I also understand that iterative plate solving and adjustment will find an object. I guess there's a limit to what can be done in summer, in the daytime...I'll just have to wait for a starry night

Thanks to all who have commented

Martin

[7170]

Just now, martinclayden said:

No, not yet, still learning the ropes with the mount in daytime use

Ok, I would recommended you do a 1-star alignment next time at night, and I suspect that will solve things.

You basically use the hand controller to go into 1-start alignment mode, select a bright star from the list that you can see, and the mount will then point the scope to where it thinks it should be. You then use the direction arrows on the hand controller to move the star into view in eyepiece then an tell the mount when it is in view. Once done the mount knows the offset due to the scope not being perfectly aligned with the NCP when it starts up.

Once aligned when you use the goto feature it should then point very close to any target in that region of the sky and should be in the eyepiece.  You can then do three start alignment in the future if you want it to be more accroute across the whole sky.

[Sabalias]

Hi Martin,

When I had my EQ5 Pro I came unstuck by not putting the right information in when initialising (garbage in = garbage out) so since then I’ve been very careful to follow the same routine every time I set up. It might be overkill but it works for me:

1. After initialising check (and double check) the data you put in (including date, clock time, and DST setting – which is YES for British Summer Time as has been mentioned further up the thread)

2. Get the mount accurately polar aligned (as far as possible)

3. Set up the scope, balance it and place in home position (I have to do this because I dismantle my setup after every session so my scope ‘home’ can vary a little)

4. Carry out a 1 or 2 star alignment

5. Begin observing/photographing etc.

Of course all of the above require a clear night; I don’t think you’ll be sure of the capability of the mount until you’ve been able to use at night.

Good luck,

Stu

[nfotis]

When setting up your HEQ5 mount, it helps to use an application like SynscanInit on your smartphone.

It uses GPS in order to give you the correct place of Polaris in the polar alignment scope, and the correct parameters to enter into the handheld computer.

After these two steps, a 2-star alignment should give you adequate accuracy when going from one target to another.

Oh, and first align your finder scope with your main scope before doing the star align procedure.

N.F.

 

Edited July 15, 2021 by nfotis

[StevieDvd]

Also, let us know what you plan to do, image or observe? Then we can tailor the info to your needs.  And any other equipment like the scope and camera(s) and software you plan to use. It all helps (as we do).

[martinclayden]

50 minutes ago, 7170 said:

Ok, I would recommended you do a 1-star alignment next time at night, and I suspect that will solve things.

You basically use the hand controller to go into 1-start alignment mode, select a bright star from the list that you can see, and the mount will then point the scope to where it thinks it should be. You then use the direction arrows on the hand controller to move the star into view in eyepiece then an tell the mount when it is in view. Once done the mount knows the offset due to the scope not being perfectly aligned with the NCP when it starts up.

Once aligned when you use the goto feature it should then point very close to any target in that region of the sky and should be in the eyepiece.  You can then do three start alignment in the future if you want it to be more accroute across the whole sky.

Cheers! I'll be patient and wait 😊

[AstroMuni]

9 hours ago, martinclayden said:

After a reasonably accurate daytime PA (compass and inclinometer) and mount levelling, I find that the initial slew to an object is consistently off; to the West and South of the object.

When you get a chance use the Polarscope to ensure that your mount is aligned correctly. I found that just setting it to our latitude using the scale on the side wasnt great. Even if Polaris gets into the middle of the circle is a great difference.

I dont know if they have updated their manual because the new reticle is like a clock face but the manuals still talk of the old one showing pictures of constellations. If not then download the manual for the HEQ6 which explains the new interface. You may also need to calibrate the polarscope itself.  This article explains it well https://www.myastroscience.com/polarscopecalibration

Edited July 15, 2021 by AstroMuni

[martinclayden]

50 minutes ago, AstroMuni said:

When you get a chance use the Polarscope to ensure that your mount is aligned correctly. I found that just setting it to our latitude using the scale on the side wasnt great. Even if Polaris gets into the middle of the circle is a great difference.

I dont know if they have updated their manual because the new reticle is like a clock face but the manuals still talk of the old one showing pictures of constellations. If not then download the manual for the HEQ6 which explains the new interface. You may also need to calibrate the polarscope itself.  This article explains it well https://www.myastroscience.com/polarscopecalibration

Thank you, good tip. I've upgraded from Star Adventurer, so I'm familiar with the principles of PA - it's just the practice I need to practice with the HEQ5

[martinclayden]

2 hours ago, StevieDvd said:

Also, let us know what you plan to do, image or observe? Then we can tailor the info to your needs.  And any other equipment like the scope and camera(s) and software you plan to use. It all helps (as we do).

I plan on imaging - using either an 8" Newt, modded Canon 60D or stock Canon 77D. 

Imaging will be guided with PHD2 and ZWO 120mm guide camera.

Control will be APT on an ASCOM platform. With this I'm looking into (not yet tried) plate solving powered by ASTAP for object alignment, which appears to offer the possibility of skipping the mount's 1/2/3 star alignment process - but it's early days for that yet. I've often used a rather laborious iterative image, solve, adjust method with a non-goto mount - so the automated method does appeal to me

As ever, I do appreciate the help given on this forum - tapping into this body of knowledge is always worthwhile.

Martin

[Padraic M]

Martin, it's worth getting to know the start-up process for the HEQ5 as outlined above. Just to emphasise, it took a while for the penny to drop with me that polar alignment and star alignment are separate things with different purposes. If you level, PA and 1/2-star align, you should be good to go. The first star goto being out is fairly standard, but the second goto should be very close.

Once you're onboard with APT and platesolving, you can throw star alignment out the window! Also, SharpCap is brilliant for very accurate polar alignment, so no more kneeling down with your neck twisted to the north star!

 

[AstroMuni]

13 hours ago, martinclayden said:

plate solving powered by ASTAP for object alignment, which appears to offer the possibility of skipping the mount's 1/2/3 star alignment process

In my opinion you would still need to do the 2 or 3 star alignment using platesolving so that the mount alignment is correct. As they say, the more stars you use to align, the better the positioning. I havent used APT, but guessing it should have a similar facility as Ekos (which I use) to select a few alignment stars automatically and then start the 2/3 star alignment.

[Budgie1]

1 hour ago, AstroMuni said:

In my opinion you would still need to do the 2 or 3 star alignment using platesolving so that the mount alignment is correct. As they say, the more stars you use to align, the better the positioning. I havent used APT, but guessing it should have a similar facility as Ekos (which I use) to select a few alignment stars automatically and then start the 2/3 star alignment.

It's not needed because you're basically aligning to the target you want to image.

Here's a quick run through of how it works:

1. PA the mount and use something like Cartes Du Ceil or Stellarium to slew the mount to where it thinks your target is (APT can do this on it's own by platesolving from the home position but I like to use CDC).
2. Take an image, tell the platesolving software what your target is and it will check the image using built-in star catalogues to see where the scope is actually pointing, then synchronise the actual position with CDC/Stellarium.
3. The software (APT) will then slew the mount to bring your target to the centre of the image, take another image to check location and adjust again if required.
4. Once you're on target you can start guiding or just remain on sidereal.
5. If you change target, you just re-run the process.

One advantage of platesolving is that you can choose exactly where the centre of your image will be. Say you want to image M81 & M82 and get them both in the frame, you just pick a spot between the two galaxies and tell APT to platesolve to that location. If you record that location you can centre on it night after night to collect more data on the same target.

The platesolving process looks long winded when typed out, but in reality it normally takes a couple of minutes and most of it is automated.

[Padraic M]

Platesolving is magic! You can retrieve an image you took on a previous night, and get APT to recentre on that exact location. No need to star align beforehand.

 

[barbulo]

I fully agree with the latest posts: plate solving is a game-changer. With a careful PA (for a precise guiding) you can skip star alignment.

[AstroMuni]

I agree platesolving is a big help, but behind the scenes, the act of doing a Solve & sync on your first object is in effect doing a 1-star alignment 🙂

So if you are planning to capture multiple objects in one night and want to save time on each platesolve and realign, then IMO doing the initial 2-3 star alignment helps refine the mount pointing model and you are going to save time on subsequent object searches and captures.

[martinclayden]

3 hours ago, Budgie1 said:

It's not needed because you're basically aligning to the target you want to image.

Here's a quick run through of how it works:

1. PA the mount and use something like Cartes Du Ceil or Stellarium to slew the mount to where it thinks your target is (APT can do this on it's own by platesolving from the home position but I like to use CDC).
2. Take an image, tell the platesolving software what your target is and it will check the image using built-in star catalogues to see where the scope is actually pointing, then synchronise the actual position with CDC/Stellarium.
3. The software (APT) will then slew the mount to bring your target to the centre of the image, take another image to check location and adjust again if required.
4. Once you're on target you can start guiding or just remain on sidereal.
5. If you change target, you just re-run the process.

One advantage of platesolving is that you can choose exactly where the centre of your image will be. Say you want to image M81 & M82 and get them both in the frame, you just pick a spot between the two galaxies and tell APT to platesolve to that location. If you record that location you can centre on it night after night to collect more data on the same target.

The platesolving process looks long winded when typed out, but in reality it normally takes a couple of minutes and most of it is automated.

There's a few good videos on YouTube about this, whether imaging with a dedicated astro camera, or via a DSLR; the process looks simple, and reliable. I like that it can done fully remotely too.