Setting Circle Help Reqired.

[RMcCallum]

Now as a bloke, I'm not usually one to ask for help, however, the time has come.

I am a most definitely a beginner and I own a Starwatcher 130M EQ-2.

The problem I have is that after manovering the telescope and inputting all the relevent RA / Dec data onto the setting circles, the telescope points in the opposite direction to that I am aiming for.

For example, looking south, in the northern hemisphere, I calibrate the RA circle on Vega (Right ascension 18^h 36^m 56.33635^s Declination +38° 47′ 01.2802″) Then I attempt to look for the Great Globular Cluster in Hercules (M13, Right ascension 16^h 41^m 41.24^sDeclination +36° 27′ 35.5″) by releasing the RA lock and inputting the 16^h 41^m (and obvioulsy tightening it again). From where I set up M13 is on the right (west) hand side of Vega (Stellarium). However, through some reason unbeknownst to me the telecope will point to the left (east) hand side of Vega. I have also attempted to use the setting circles to move from Vega to Altair two stars that are reasonable close and bright. Yet again my telescope pointed in opposite direction and not at Altair.

In addition, I do own a motor, however I would like to be a 'complete' astronomer and learn how to use all methods of locating objects in the sky ie. manually using setting circles, star hopping ect.

Can anyone provide and assistance?

Kind regards,

Rupert.

[NGC 1502]

Hi Rupert, welcome to SGL. I no longer own an EQ mount, so cannot go to check. I may have this wrong, but on the EQ mounts I had, the RA circle had two scales,

one for use in the Northern Hemisphere, the other for Southern Hemisphere. Are you using the correct one ?

The setting circles on many EQ mounts are not terribly accurate, but should at least put you in the general area, not completely in the wrong bit of sky that seems to

be happening to you.

If all this is drivel ( I am totally alt - az ) someone will hopefully say so

Hope you sort it, Ed.

[glowjet]

Hi Rupert and welcome to SGL, I am afraid the setting circles on most scopes for the general market nowadays are not really big enough to be of any assistance in locating objects, as they and the sub divisions are to small to be of practical use albeit they could, with care, get you somewhere near. First you have to establish that you are using the correct scale for the Northern Hemisphere. To set the scale, you don`t set the scale and move the scope, it is in fact done the other way round eg, after setting up the scope properly Polar aligned as best you can, use a cross hair ep if you have one, point your scope to a bright star of known value, accurately centre it in the field of view, its positional value will be given in star tables, now set your RA circle as best you can to the values followed by the Dec measurement. The circles should not be locked but move with the scope, they should have some friction so that if you want to alter their position you can. One method adopted in the Sates is known as DEC sweeping, if you have a target you want to search out, then choose a bright star near to where you want to be and set the RA on the scale, you only now need to subtract or add to the RA given for your target and move the scope the small amount, then using a widefield eyepiece slowly sweep in DEC and the chances are you will find what you are after. I think this about right, someone will shout if I have made an error

John

[RMcCallum]

Thank you very much for your replies and welcomes.

The upper set of numbers apply to viewing in the Northern Hemisphere, while the numbers below them apply to viewing in the Southern Hemisphere

As to the correct scales I have been using the upper set of numbers (I hope), but I don't suppose it would harm in trying the other set just to be thorough, you never know where a typo might appear.

DEC sweeping sounds interesting and I will definately be giving it a go.

I must say, I am totally hooked and cannot wait for night to fall.

Rupert.

Edit: Aww man I spelt required wrong. Dammit.

[pallas15]

Im by no means an expert having only recently got my scope (same one) but im having some success with mine.ill list how mine works..hope it helps.

1:level tripod

2:set mount head to point north.Insure your AZ lat is set locally...I use 52degrees-uk..

3:set Dec to 90degrees

4:thats the start position.

5:now unlock the RA/DEC locks and manually find an object you know i.e Vega or Arcturus...whatever your sure of.

6:check the coordinates for the object RA hours + mins--------------DEC + or - Degrees

7:Unlock DEC and move head until the DEC amount lines up with the metal pointer.lock the DEC.i.e. Vega 38degrees.

8: above the RA scale is a tiny thumbscrew that locks the RA setting circle...undo it so the circle moves.

9:unlock the RA and slew your scope to center the object(whatever method you use..red dot ...eye piece..etc)

10:when your happy with position lock the RA and rotate the RA setting circle to line up the hours and mins value with the metal pointer.i.e Vega 18H 36 M..

11.There are two scales on the RA setting circle..The top scale is northern hem...bottom scale southern.Use the scale that increases clockwise.each increment is roughly 10 degrees so rotate the circle to 18 hours and roughly 3 or 4 increments.

12:double check ..center the object.. tweak the RA setting circle and DEC slo mo till your happy you cant get any nearer.

13:Thats now calibrated..if you now swing your scope to another set of co-ordinates but don't rotate the RA setting circle ,just line up the value and pointer(RA).Unlock the DEC and line up the value to the pointer and look through the eyepiece (25mm) the object should be visible.Pick easily recognizable for a few times to key in any little variations.You wont pinpoint the center of the object but it will be close.

Many factors have a negative effect...poor Alignment to the C.N.P.............Incorrect AZ lat setting..........not calibrating the setting circle.The RA setting circle is the only adjustable one.You can lock it off so that it rotates with the RA mount but you cant set it to a known value unless its unlocked and then not readjusted unless your making major jumps.

Using it that way ,last night for example I planned to observe an area of clear sky.

I successfully moved and positioned(in the 25mm eyepiece)..M101---Galileo satellite---Alphekka----Great cluster-----Cebalrai-----IC4665---Rasalhague.All object were in my view..not dead center but within a degree or two..certainly near enough to find.

I really don't know why or how im having success as many people say they don't work...I tried and found them usefull..at least pointing me the right way...

No they aren't 100% pinpoint but as long as you take into account that you may be a few degrees out either way, then I think they can work.My first try was just a three bright ,well known star collection.. calibrating on the first then checking the scales on the other two and luckily enough the values were very close to the stellarium co-ordinates..

might be just beginners luck though hehe....hope this helps...looks like a long list but its just a minute really if you've set up correctly and not moved the tripod or mount from the polar aligned position.......chris..

[Merlin66]

As stated..once you've set up the circles on a known object, they should not be "re-set"

The Dec and RA should rotate relative to the pointer on the fixed part of the mount.

Just try setting it to say Vega....swing the telescope off the star by a few degrees, then use the co-ordinates to re-find Vega.

If that works..then you can get more adventurous.

[glowjet]

Just to add a little more info to my previous thread concerning the setting circles being able to be moved, not loose but with some friction, this was raised by Scott Losmandy some time ago, they used to provide their mounts with locking screws on the setting circles but now these have a nylon screw to provide positive friction. Scott found that much of the inaccuracies occurred when the scope was slewed over considerable distances about the sky, It then seemed more logical, if you had traversed to a vastly different part of the sky, to reset the RA circle to a known co-ordinate near to your target and work the short distance on the setting circles from there, which is how I believe the DEC sweep method came about

John.

[pallas15]

Im by no means an expert having only recently got my scope (same one) but im having some success with mine.ill list how mine works..hope it helps.

1:level tripod

2:set mount head to point north.Insure your AZ lat is set locally...I use 52degrees-uk..

3:set Dec to 90degrees

4:thats the start position.

5:now unlock the RA/DEC locks and manually find an object you know i.e Vega or Arcturus...whatever your sure of.

6:check the coordinates for the object RA hours + mins--------------DEC + or - Degrees

7:Unlock DEC and move head until the DEC amount lines up with the metal pointer.lock the DEC.i.e. Vega 38degrees.

8: above the RA scale is a tiny thumbscrew that locks the RA setting circle...undo it so the circle moves.

9:unlock the RA and slew your scope to center the object(whatever method you use..red dot ...eye piece..etc)

10:when your happy with position lock the RA and rotate the RA setting circle to line up the hours and mins value with the metal pointer.i.e Vega 18H 36 M..

11.There are two scales on the RA setting circle..The top scale is northern hem...bottom scale southern.Use the scale that increases clockwise.each increment is roughly 10 degrees so rotate the circle to 18 hours and roughly 3 or 4 increments.

12:double check ..center the object.. tweak the RA setting circle and DEC slo mo till your happy you cant get any nearer.

13:Thats now calibrated..if you now swing your scope to another set of co-ordinates but don't rotate the RA setting circle ,just line up the value and pointer(RA).Unlock the DEC and line up the value to the pointer and look through the eyepiece (25mm) the object should be visible.Pick easily recognizable for a few times to key in any little variations.You wont pinpoint the center of the object but it will be close.

Many factors have a negative effect...poor Alignment to the C.N.P.............Incorrect AZ lat setting..........not calibrating the setting circle.The RA setting circle is the only adjustable one.You can lock it off so that it rotates with the RA mount but you cant set it to a known value unless its unlocked and then not readjusted unless your making major jumps.

Using it that way ,last night for example I planned to observe an area of clear sky.

I successfully moved and positioned(in the 25mm eyepiece)..M101---Galileo satellite---Alphekka----Great cluster-----Cebalrai-----IC4665---Rasalhague.All object were in my view..not dead center but within a degree or two..certainly near enough to find.

I really don't know why or how im having success as many people say they don't work...I tried and found them usefull..at least pointing me the right way...

No they aren't 100% pinpoint but as long as you take into account that you may be a few degrees out either way, then I think they can work.My first try was just a three bright ,well known star collection.. calibrating on the first then checking the scales on the other two and luckily enough the values were very close to the stellarium co-ordinates..

might be just beginners luck though hehe....hope this helps...looks like a long list but its just a minute really if you've set up correctly and not moved the tripod or mount from the polar aligned position.......chris..

checking the sky watcher manual there are two diagrams --eq1 mount and eq2 mount ..the instructions say use the top but on the eq2 mount the scale is the opposite way around..use the setting circle scale that rises in a clockwise direction....

[LukeSkywatcher]

I'm pretty sure the setting circles on my EQ mount (90mm refractor) are purely there for decoration.

[pallas15]

I'm pretty sure the setting circles on my EQ mount (90mm refractor) are purely there for decoration.

I know exactly what you're saying..thought it was a happy coincidence that they worked for me..tried again tonight..lined up arcturus with the also useless red dot scope ...checked ep..pretty close to center...checked DEC..maybe a couple of increments off....turned RA to hours and minutes...jumped across to alkaid..checked DEC...pretty near again,maybe 1 or 2 degrees out...checked RA setting circle...hours correct minutes as near as....dont know why it seems to work...I think mainly im going for the "big hitters".think theyre not accurate enough for fainter DSOs etc....same as the red dot finder...not a prob....honest ,not telling porkies ...maybe as i get more experience my expectations will grow and ill want to be more precise ..

[LukeSkywatcher]

I know exactly what you're saying..thought it was a happy coincidence that they worked for me..tried again tonight..lined up arcturus with the also useless red dot scope ...checked ep..pretty close to center...checked DEC..maybe a couple of increments off....turned RA to hours and minutes...jumped across to alkaid..checked DEC...pretty near again,maybe 1 or 2 degrees out...checked RA setting circle...hours correct minutes as near as....dont know why it seems to work...I think mainly im going for the "big hitters".think theyre not accurate enough for fainter DSOs etc....same as the red dot finder...not a prob....honest ,not telling porkies ...maybe as i get more experience my expectations will grow and ill want to be more precise ..

Ive only ever used my 90mm refrac on the EQ mount as a "point and shoot" scope or more like an Alt-Az.

Honestly............Hrs,mins and second mean NOTHING TO ME.

Its no wonder that i dont use EQ mounts any more.

Give me a Dob that i can point to where i want it to point or a Go-To that goes to exactly where i want it to go.

EQ and me simply do not get along.

[pallas15]

having got the eq instead of the dob that most people recommended i can see the merits and useability of the dob mount over the eq.luckily in my situation i have ample time to set it up and find the viewing position comfy for me.one advantage i can see with the eq is that i can alter the scopes height to pass over obstructions such as fences and bushes near my location.i think with a dob mount i may have a more limited viewing area,but having said that if or when i upgrade and i sort out an ideal position ,a large dob would probably be best.At the mo the eq is teaching me a lot about the sky and scopes in general..i would like a goto to seek out those hidden treasures,but that will be when i get a scope capable of seeing more.Oh wanna thank you for your advice and help on scope choices when i joined recently..very helpful..only budget changed my choice ......