Using wixey with a dobsonian - do I need co-ord conversion?

[StevieDvd]

Ok so I have a wixey coming soon to fit on my Skyliner 200p dob, I understand the usage of that to get the altitude, and the missing setting being the azimuth which I swing the dob to point at.

But what confuses me is the talk of needing to so some maths or use a program to convert the co-ordinates.

If I have stellarium of another astronomy app won't that have the co-ordinates in the form I can use?

Thanks

Steve

[themos]

Yes, Stellarium will show you the Altitude/Azimuth coordinates of your selected object. Bear in mind that these numbers will be visibly changing all the time. You need to give Stellarium your latitude/longitude coordinates of your observing location and the correct time.

[insomnia]

I use a useful android app called Whereisit. Very basic but gives live coordinates in the right format. Another good app is Star Walk

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[brianb]

Stellarium will show you the Altitude/Azimuth coordinates of your selected object. Bear in mind that these numbers will be visibly changing all the time

But the altitude will not change by more than 1/4 degree in a minute, and the change will usually be much less than that, especially if you observe the object when it is best placed - on or near the meridian.

The Wixey altitude gauge is not a substitute for a full "push to" system, you still have to search in azimuth, but it does make it easier to locate the field in which the object lies. A good finder - with magnification, 8x50 or 9x50 are good for most scopes - can be very helpful, as can a wide field low power eyepiece on the main scope.

[insomnia]

Make sure the scope is on level ground, as this can really screw up the alt

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[StevieDvd]

Thanks,

So for example using Betelguese, Starwalk shows Azm 121.04.31 and Alt 31.04.35.

I raise the dob until wixey shows 31 and swing the base around to compass 121 degrees. Assuming my location is preloaded in and I know which way I'm facing.

Or am I deluded

I am only after a rough direction that's why I got the dobsonian. The Nexstar 4se is my goto guy and can does it own calculations.

[insomnia]

That will def put you in the correct location, just minor tweeks should put it in the eyepiece

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[StevieDvd]

Thanks all.

Maybe I'm starting to get the hang of this....

[ken rigg]

Thanks,

So for example using Betelguese, Starwalk shows Azm 121.04.31 and Alt 31.04.35.

I raise the dob until wixey shows 31 and swing the base around to compass 121 degrees. Assuming my location is preloaded in and I know which way I'm facing.

Or am I deluded

I am only after a rough direction that's why I got the dobsonian. The Nexstar 4se is my goto guy and can does it own calculations.

Hi stevie,sorry to jump on your post but when you say swing the base around to 121 degrees do you start as 1 degree being the pole star?

[StevieDvd]

Hi stevie,sorry to jump on your post but when you say swing the base around to 121 degrees do you start as 1 degree being the pole star?

I was thinking of North being 0 degrees, though I may be wrong. I would put it into practise, assuming we get some nice clear skies, by using the moon as a test subject.

[Daz Type-R]

Can you keep us updated on how you get on, I too have a wixey on order and seem to be doing the exact same thing as you!

[StevieDvd]

Can you keep us updated on how you get on, I too have a wixey on order and seem to be doing the exact same thing as you!

Sure will. Though the phrase blind leading the blind springs to mind no disrepect intended.

[Daz Type-R]

Non taken.

[StevieDvd]

Gadget freak that I am on a whim I've just ordered a digital compass with a mind to seeing how it copes with the skywatcher.

In my minds eye I see the compass velcro'd to the base of the skywatcher and showing the azimuth in digital readout form. As long as it is on the same line as the scope it will be pointing the right way.

Trust me to choose a digital option rather than analog (printed setting scales).

Plus I get another pressie in the post in the next few days

[bcfcciderhead]

Use Polaris as north (it's slightly different to a compass, but not a lot) and make sure the dob base is level, this WILL make a difference.

Check out my mods i done to my dob, fitting scales to the base, might give you a little help. But you on the right track.

http://stargazerslounge.com/diy-astronomer/129979-dob-setting-circules-azimuth-altitude.html

[StevieDvd]

I've bookmarked the settings circles and examples (yours included) of modded bases. I'm still in that 'only just got the scope' period to start modding it too agressively.

[insomnia]

I have tried a digital compass, and to be honest it failed miserably. The scope interferes with the compass like crazy, it sends the compass crazy with miss-readings, a printed circle is the only reliable way to go

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[StevieDvd]

I have tried a digital compass, and to be honest it failed miserably. The scope interferes with the compass like crazy, it sends the compass crazy with miss-readings, a printed circle is the only reliable way to go

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I was half expecting that thought I'd give it a go, if it fails at least I have a compass.

[Talitha]

Make sure the scope is on level ground, as this can really screw up the alt

IIRC, the scope only needs to be level when you're using an ALT circle, but i could be mistaken.

[bcfcciderhead]

IIRC, the scope only needs to be level when you're using an ALT circle, but i could be mistaken.

I believe your correct Talitha, 360 degrees will always be 360 degrees even if not level, but the ALT scale will be out if not level, for example if you want to raise the scope to a 45 degree angle, if the base is not level it could be 50 degrees or 40 degrees and so on.

[StevieDvd]

As long as the wixey is correctly levelled when set to zero then if the scope base is not level it should be OK.

The worst option would be to set the wixey to zero using an unlevel base as a reference.

I think ......

[rabbithutch]

Most of the replies to the OP confused me; so I must not have understood the question.

As I understood it, Steve was concerned about having to do math to convert altitude bearings. That meant, to me, that he was concerned about converting degrees/minutes/seconds to degrees/decimal_value. I guessed that the Wixey does not display deg/min/sec but uses decimal only.

Are my assumptions wrong? Can the Wixey be set to display either format?

Yes, either format presumes that the starting point is level or at zero degrees if one is trying to point to a given altitude (RA?) to find something based on a star chart or a computer application. And, yes, the object to be viewed will ultimately bear at a different angle; but, at any given time, the RA should be predictable. No?

Help please?!?

[StevieDvd]

Most of the replies to the OP confused me; so I must not have understood the question.

As I understood it, Steve was concerned about having to do math to convert altitude bearings. That meant, to me, that he was concerned about converting degrees/minutes/seconds to degrees/decimal_value. I guessed that the Wixey does not display deg/min/sec but uses decimal only.

Are my assumptions wrong? Can the Wixey be set to display either format?

Yes, either format presumes that the starting point is level or at zero degrees if one is trying to point to a given altitude (RA?) to find something based on a star chart or a computer application. And, yes, the object to be viewed will ultimately bear at a different angle; but, at any given time, the RA should be predictable. No?

Help please?!?

The wixey readout is just in degrees, it's a tool used for things like setting angles on saws and other tools.

Luckily there are a few programs for laptops, pds's and iphone (yay!) which have the altitude in degrees as well. What worried me was that the altitude degrees were different in some way than that shown on the wixey.

So for basic dob manual goto a 360 degree scale for the azimuth and a 90 degree scale for altitude is OK with the right co-ordinates from the software.

Is that clearer or am I making it murkier?

Steve

[rabbithutch]

OK, Steve.

I understand (I think). If the Wixey gauge readout is in degrees with several decimal places of precision - but does not display degrees/minutes/seconds - then when you are using charts that show for example, 31° 5' 52", then you must convert that reading to 31.0980556° to read the Wixey on that heading.

All that assumes that your reference gives you the declination for a given time. After you have found the object of choice, you will have to nudge the dob to keep the object in view. For other mounts, there is software that will drive those mounts to keep the object in the field of view.

[Macavity]

On the Azimuth alignment: I you draw a degree scale on the Dob base, you can do a "1-star (Pole star!) alignment", rather than messing with a compass etc. Heaving a big Dob [base] around, for initial setup might not be fun, but, once done, you can mark the base position onto the ground - For posterity!

The principle works surprisingly well with smaller alt-azimuth systems too - Think "school protractor"! It helps considerably if you have a decent finder - Getting the scope within the typical 4-7 deg field is then rather easy. The Wixey can read altitude to ~0.2 deg (i.e. less than lunar diameter!) on the sky, after careful leveling of the mount.