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Digital Setting Circles

Moonshane

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Moonshane

Moonshane

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Hi all

I am going to get a device Astro-Fix Locator which gives digital setting circles for azimuth and altitude (altaz) for my dobs. the problem of course is that most books give right ascension and declination (radec) corordinates rather than altaz.

Is a PDA /laptop with software the only way that I can get altaz coordinates for objects other than bending my brain with trigonometry?

What do others use please? to get their targets?

Thanks

Shane

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pvaz

pvaz

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You need to factor the cost of the individual pieces and see if it is any cheaper then a GOTO system.

I often see people calling the setting circle/inclinometer route as a non GOTO, but bare with me a bit:

What do you call a system containing the following?

1) A database with objects RA/DEC coordinates. (it can be a user with an atlas, a planetarium software or that info stored in digital format on a device's memory)

2) A way to translate those coordinates to Alt/Az using location and local time. (could be a user with pencil and paper, a PC running planetarium software or another device's CPU)

3) A way to measure the current Alt/Az coordinates. (setting circles/inclinometer or sensors attached to the base sending that info to a device)

4) A way to point the scope to the calculated Alt/Az coordinates (either a user moving it manually or a motor)

From my perspective the combination of user-atlas-software-scope motion is nothing but an archaic GOTO system.

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Moonshane

Moonshane

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You need to factor the cost of the individual pieces and see if it is any cheaper then a GOTO system.

I often see people calling the setting circle/inclinometer route as a non GOTO, but bare with me a bit:

What do you call a system containing the following?

1) A database with objects RA/DEC coordinates. (it can be a user with an atlas, a planetarium software or that info stored in digital format on a device's memory)

2) A way to translate those coordinates to Alt/Az using location and local time. (could be a user with pencil and paper, a PC running planetarium software or another device's CPU)

3) A way to measure the current Alt/Az coordinates. (setting circles/inclinometer or sensors attached to the base sending that info to a device)

4) A way to point the scope to the calculated Alt/Az coordinates (either a user moving it manually or a motor)

From my perspective the combination of user-atlas-software-scope motion is nothing but an archaic GOTO system.

ha ha

this is a fair comment Paulo and in a way, it's your fault I am looking at this! :) you have changed my mind a little with regard to GOTO and I saw this as a cheaper option - total cost will be maybe £150. the advantage is that it can be taken off one scope and plonked on another for no additional cost.

no idea though what a goto/push to system would cost but surely a lot more than this for one and certainly two systems? also, I think manual push to systems like this are a lot quicker than the average goto?

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pvaz

pvaz

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I believe the push to can be faster then a goto only if the slew motion is too slow. A motorized GOTO haves a very big plus: Tracking! That can make planetary observation much more enjoyable.

The XT8i "intellisense" PushTo system is made of:

- 1 sensor for alt (replaces the inclinometer)

- 1 sensor for az (replaces the setting circle)

- 1 controller containing the objects database and able to calculate the alt az coordinates. It's actually very well programmed, by starting it when pointing to zenith and with another 2 points (2 star allignment) it triangulates the data and infers my position/local time. If this is done correctly it works like a charm. I can at any point add another point to the calculations to improve accuracy (I often choose a 3rd object).

Then I just need to do something like:

Press Catalogue key, enter number, press enter, point while following directions (left, right, up, down), look with a widefield EP, center the object...

Pressing enter again I get the object mag, apparent size, Equatorial coordinates and a brief text explanation.

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GazOC

GazOC

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I've used the astro fix locator and, while it does what it says on the tin, don't underestimate how fiddly it is to check the PDA for aly/az, look at the inclometer reading, look that the az meter reading, push the scope, recheck the inclinometer reading, recheck the az meter reading, move the scope.....

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Moonshane

Moonshane

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I've used the astro fix locator and, while it does what it says on the tin, don't underestimate how fiddly it is to check the PDA for aly/az, look at the inclometer reading, look that the az meter reading, push the scope, recheck the inclinometer reading, recheck the az meter reading, move the scope.....

all very true.

I am still in research mode thankfully and this is all fab advice.

I have been OK so far without anything like this and do like the thrill of the chase but it's the comments of others using Wixeys and manual setting circles on dob bases, with apparently good rates of success, which have fired my curiosity.

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GazOC

GazOC

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this does sound very cool Paulo but I fear the aftermarket options for dob GOTO are extremely expensive?

The latest kits can be (very!) expensive but I picked a S/H Meade Megellan DSC kit for £90 last year. Its an older generation kit but the encoders are accurate and it has all the Messier and NGC objects (ie plenty!).

Maybe a "wanted" ad will turn up something suitable?

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irishbloke

irishbloke

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The astromist program is excellent. there's a free version that does the job very well. Just need to input your location each time you enter, either selecting a nearby town or entering co ordinates. I had a 2.6 version on my 2nd hand dell axim x30 and then saw there's an updated version 3.0 or so. This is much better and slicker and has me close to purchasing the full version. theres a cool map of the moon system and moons of planets sections. Definitely worth a look.

I also tried Tachyon but found my pda not powerful enough and it was harder to use.

Brian

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Moonshane

Moonshane

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cheers Brian

I presume you need the 600mb min card too for the pics in the software? what card do these take please? they seem pretty cheap on Ebay - about £30.

I reckon if I can get this system all in for £120 it's got to be worth a punt. (see what I did there? Irishbloke....punt.....)

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irishbloke

irishbloke

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LOL Sorry I'm northern ireland but i enjoyed the pun!!!

I have a 2 GB card which i got for under a tenner in tesco. The PDA's are cheap on ebay. I've had a go at finding stuff using the wixey and a compass which worked ... ish. I have to sort out a setting circle thing and leveling feet. I need to bite the bullet and just put up with the inflated postage costs for across the drop of water.

Brian

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Doc

Doc

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You should get the Wixey and the base setting circle Shane. Get your co-ords off CdC and you'll be bang on. Doc does this on a netbook and LB quicker than I can use a goto handset lol :)

Total cost under £30!!

Totally agree mine is all set up for £30 and is just as accurate as any go-to.

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Moonshane

Moonshane

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cheers guys. my main problem with the setting circles on the base is that the OO dob base is not really conducive to putting a circular scale on it. this is why I started thinking about the digital compass and wixey and which led me to the unit mentioned above. it's £60 more than a wixey fair enough and I'd need a PDA anyway whatever method I use. with this unit I can also switch it from one scope to another at a whim.

I'll take everything on board though and come up with something.

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vlebo

vlebo

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On a slightly seperate note Moonshane , how do you find OOUK products ? I am looking at buying their OD 400 dob and was wondering if build quality , fit and finish is of a good quality. Sorry to go off topic.

Vlebo

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Moonshane

Moonshane

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personally, I feel the quality of finish is great. their bases are second to none and their optics are world renowned. with any dob, there's always room for mods and that's the beauty of them but I'd have no issues recommending OOUK. if you can afford it, I'd recommend optical grade of at least 1/6PV and HILUX coatings and it's 'only £180' more for 1/8 - even better. this makes a big difference and the optics will certainly be better than the UK skies allow!

I am in the same boat as you it seems. I doubt a 400mm OOUK dob will ever come on the market used for a very long time and therefore it's a matter of buying new. I have decided to save for this and have budgeted £2500 which will take me a while. like you I have a good 12" dob in the meantime.

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