Star Watcher 130p Setting Circle Help

[gjcwilliams]

Hi,

I have recently purchased a Star Watcher 130p, I have not used it yet as it has been too cloudy, however I have been reading up on how to navigate using the setting circles and I am confused about operating the Right Ascention dial.

I understand the theory behind Right Ascention and Declination but I just want to clarify how am I supposed to calibrate it. My understanding is this requires calibrating and from what i have read numerous guides suggest finding a bright star such as Vega then setting the dial to the coordinates of that star. Either I am misinterpreting the instructions but how do I know which star Vega is without guessing and theres a good chance I will be wrong??

Also see below picture, I am not sure if i was meant to but i initially unscrewed the adjuster (circled red) it allows the RA dial and the pointer (orange) to move independantly. If i tighten it when and try and rotate the telescope both the pointer (orange) and the dial move together as a unit. Under normal operation should this adjuster be loose so they move independantly or tight so they move together as if they are one unit?

Finally when trying to navigate to an RA coordinate should i be lining the RA time to the marker circled in orange or the one in purple?

Any advice would be much appreciated.

Thanks in advance.

[gjcwilliams]

<a href="http://imgur.com/uQglQ45"><img src="http://i.imgur.com/uQglQ45.jpg" alt="" title="Hosted by imgur.com" /></a>

[gjcwilliams]

Apologies, please see below image.

[rwilkey]

To be honest, I think few people use the setting circles, I for one, as they are impossible to read in the dark, especially on small rigs. I find it best to star hop, much easier and less faff.

[glowjet]

As Robin has intimated few people use them as the divisions on the circles are far to small to resolve minutes and seconds of a star coordinates position. I may be wrong, but I think the scale you have indicated in Purple is intended for Southern Hemisphere users. The free program Stellarium will help you locate the major known stars and will give you all the necessary information, binoculars can help in your search, as they give a much wider field of view and it is a question of, with practice, learning your way about the night sky

John.

[Neil_F]

I too have a Sky Watcher 130P, and to be honest I have to agree with Robin. Setting circles are flippity gibberish to me too, so I tend to "star hop" my way around the cosmos. More time enjoying the wonders of the sky at night, less time farting around with shiny twirly things.

Just my 2p worth.

[the bishop]

Oh my! setting circles good in theory but I’m with Robin with this

I have a 130 on an EQ2 and the setting circles are a joke

They are so small and all but impossible to get a tidy reading in the dark let alone

in getting them set up

From what I gather even the bigger mounts are not that much better??

Star hopping is the way to go and the best way to help you learn your way around the sky

Some good clear nights would help and a deal of patience get yourself a planisphere or star chart book

or download maps or stellarium on a laptop and before you know it you will be star hopping and finding all sorts

[PARTY MARTY]

I have setting circles on my EQ-5 mount! And they are rubbish! They aren't accurate and you need a science degree to work them out! To be honest with you I agree what most of the guy's said, Use star hopping and use good star map that works much better! One thing I found that a Telrad is best thing to use when star hopping! I would highly recomend buying a telrad, they are much better than a finderscope and makes aiming the telescope towards targets much easier! I would go to FLO and get yourself one, Once you got one, you'll see how good it really is!!

[the bishop]

Yep I agree about a Telrad

I have just recently got a Telrad and I find it just great

I downloaded the star charts,they are great... its very easy to set up and to use

Its far and away better than a red dot finder and wont break the bank .

[gjcwilliams]

Thanks everyone for your feedback much appreciated, guess I will do some reading on star hopping. I take it with star hopping you don't need to bother polar aligning your mount?

[the bishop]

Hi,

It really would be very helpful to have the mount polar aligned...

Well as polar aligned as you can if only roughly aligned as getting the

mount facing north helps with the way you move the scope.

My first couple of times I just set it level and struggled like mad to get

the scope into the right position, however when I set it as north as I can

( I can’t see Polaris coz my house is in the way ) it was has been much,

much better and far, far easier to track. That along with turning the OTA to suit

my position I find i don’t play twister every time and end up putting my back out

so get a sight of Polaris if you can (or even a compass) to get (a rough) north position

and try that....works well for me

[Neil_F]

Yes Bishop, that's pretty much what I do. Even if I align my scope mount on Polaris, I am guessing that my patio isn't 100% level, so if I try and track something in the southern hemisphere, after about 20 or 30 degrees my scope is out of alignment with the object. I must add that having a red dot viewfinder really makes lining my scope up.

[DaveJFT]

My garden slopes at about 1:5-1:6. I bought myself a cheapie 15mm bullseye spirit level from Amazon to set my EQ2 tripod horizontally through all 3 legs. This is my setup routine:

1. I take the mount off and carefully lay the scope and mount on the grass (or leave it in the car if I'm out) and level the top plate of the tripod using the spirit level.

2. I refit the mount and scope and centre the Dec worm drive.

3. I balance the scope in the OTA rings (I usually just assume the counterweight hasn't been moved).

4. As best I can, I "zero" the Dec and RA adjustments and lock them off.

5. Using just the Alt and Az adjustments of the mount I polar align on Polaris and lock them off. Then I recheck the alignment of the red dot finder on Polaris.

6. Finally, I spin the OTA in the rings so that the focuser is pointing straight up (normal to the RA axis). This was a tip given to me on here that means that most of the time I don't need to touch the OTA rings again and risk mucking up my balance.

This all takes me no more than 5 minutes while my scope is cooling off.

Sent from my ASUS Transformer Pad TF700T using Tapatalk HD

[DaveJFT]

I ought to add that going through this routine means that once I'm on an object I don't need to touch the Declination again as all that is required is to slowly turn the RA to keep the object in the eyepiece - the whole point of an Equatorial mount. A few weeks ago I bought a cheapie RA motor drive and now I've got the speed set on that I can stay on an object until I get bored of looking at it without touching the mount at all.

BTW, the RA on an EQ2 is different to the Dec in that the worm drive is infinite whereas the Dec worm drive has end stops and needs to be centred.

Sent from my ASUS Transformer Pad TF700T using Tapatalk HD

[hughjselby]

The Correct RA setting circle to use in the northern hemisphere is the one where the figures increase as you move the circle to your left, I.e. if you start with, say, 10. Hours facing you, then move the circle to your left and 11 hours is now facing you, that is the correct scale to use. If it helps to clarify this, stand facing south . The stars will appear to rise at your left side, pass their highest point when directly in front of you, and slowly set as they reach your right side. Now slowly rotate your body to the right so that you are facing north, and if you could view yourself from above, that is the direction your RA setting circle should be turning ! Alternatively, if you can grasp the idea, a star with a RA of 10 hours will be on the southern meridian one hour earlier than a star with a RA of 11 hours ( and one hour later than a star with a RA of 9 hours.). Hopes this helps!