RA scale

[misck1]

I am new to astronomy and have purchased a HEQ5 Pro GOTO mount.

I have been looking at various instructions how to set it up. In a tutorial called Astro Babys HEQ5 for idiots page it says that the top scale on the RA ring should be used for Northern Hemisphere and the times on this scale read from Right to Left. On looking at the Astronomy Shed You Tube videos it says the RA ring should use the scale which reads from Left to Right for Northern Hemisphere.

Which one is correct?

[skfboiler]

I saw that video and was wondering the same thing. The instructions for my mount says to use the top scale and the few times I've use the setting circles, the top scale seem to work. I'm looking forward to other responses to this topic.

[bingevader]

With any luck Astro Baby will be along any time soon to enlighten you!

[misck1]

Thank you both for your comments. I have been looking at a few other sites and appear to have conflicting reports on which scale to use. One site refers to use the inner or the outer scale and here is another site with reference to setting up the HEQ5 http://www.dulcemelos.ca/astronomy/HEQ5/index.asp

I have been using the scale which reads from left to right (ie the hour numbers are increasing) which appears to work.

[Gomtuu]

I have an EQ5 GOTO and an NEQ6 GOTO and would be interested in the answers here.

I started out trying to use the setting circles, but found that with a GOTO, you don't need to. As long as you align Polaris near enough (i.e. roughly on the celestial pole), it's fine for observing as long as you do your star alignment correctly.

Maybe I'm too reliant on technology, but that's me.

[baggywrinkle]

I have a simple EQ mount (Celestron handraulic type) and it has two RA scales one on top of the other. The top scale is for Northern hemisphere and the bottom for the Southern. Does that help any? It would make sense one reads left to right and the other right to left.

[misck1]

I know that some sites say use the top scale for Northern hemisphere and others appear to say use the bottom. The guy in the Astronomy Shed says that some manufacturers put the scale which reads from Left to Right on the bottom and other manufacturers put it on the top. He even said that sometimes the same manufacturer can switch them around in different mounts and gave Sky-Watcher as an example. I found a mount that has neither scale on the top or bottom but has them as an inner and an outer ring. So in that example which one is correct? I appear to be leaning to the idea that in the Northern hemisphere it should be the scale that reads from Left to Right (i.e. the hours increasing). I must stress I am absolutely new to astronomy and have put this up to try and resolve my confusion that I have uncovered by scrolling through various sites when I was setting up my mount.

[glowjet]

For those without the benefit of GOTO, Other than Polar alignment, once you have established the correct scale it has often been asked, "can these scales help to locate stars from positional information", as given given in reference books, star maps etc. This is nigh impossible, due to them being very small and with often inaccurate divisional spacings, just remember that small division has to be divided by 60 for minutes and again by 60 for seconds. Where you just may gain some advantage is once your equipment is set up, by pointing your scope to a known star near to a chosen target, set the RA to the reference given, calculate the positional difference between the two objects from your reference source, round up to the nearest degree, then move the scope to the new RA position. Using a nice widefield eye piece slowly move up and down in Dec, with any luck your target may appear in the field view, our American cousins call this method Dec sweeping, often used by our Dob users who have much larger and accurate setting circles. However, this is just something you might like to try, the majority find their way about the night sky by star hopping using a Telrad or the like. Have fun

John.

[cosmological]

For those without the benefit of GOTO, Other than Polar alignment, once you have established the correct scale it has often been asked, "can these scales help to locate stars from positional information", as given given in reference books, star maps etc. This is nigh impossible, due to them being very small and with often inaccurate divisional spacings, just remember that small division has to be divided by 60 for minutes and again by 60 for seconds. Where you just may gain some advantage is once your equipment is set up, by pointing your scope to a known star near to a chosen target, set the RA to the reference given, calculate the positional difference between the two objects from your reference source, round up to the nearest degree, then move the scope to the new RA position. Using a nice widefield eye piece slowly move up and down in Dec, with any luck your target may appear in the field view, our American cousins call this method Dec sweeping, often used by our Dob users who have much larger and accurate setting circles. However, this is just something you might like to try, the majority find their way about the night sky by star hopping using a Telrad or the like. Have fun

John.

But it can help, I know from experience.

My last (none goto) telescope had setting circles, once I'd found a star of known RA and Dec I would then set the setting circles and then point it to a RA and Dec for a certain object, although it would never get the object in the eyepiece but it would get close, I just needed to do a sweep of a small area of sky and I would soon find the object in question, it worked every time.

[Jaykay495]

I've been researching this too, and will be doing as cosmological says on my next clear night. I have a non-goto, and need a bit of help getting around. Am hoping this'll be just what i need, rather than guessing my way around my LP sky.

[glowjet]

But it can help, I know from experience.

My last (none goto) telescope had setting circles, once I'd found a star of known RA and Dec I would then set the setting circles and then point it to a RA and Dec for a certain object, although it would never get the object in the eyepiece but it would get close, I just needed to do a sweep of a small area of sky and I would soon find the object in question, it worked every time.

Great that you had some success with it, but it does help if you are not moving the scope a large amount in RA, as this is were the discrepancies begin to build up and you wind up with your intended target subject out of the field of view. In addition, the modern eyepieces that are now available, with a much wider FOV are also a distinct advantage using this method, than was the case some time ago

John..

[cosmological]

But it can help, I know from experience.

My last (none goto) telescope had setting circles, once I'd found a star of known RA and Dec I would then set the setting circles and then point it to a RA and Dec for a certain object, although it would never get the object in the eyepiece but it would get close, I just needed to do a sweep of a small area of sky and I would soon find the object in question, it worked every time.

I must add that the telescope needs to be fairly well polar aligned, I used to spend about an hour getting the telescope polar aligned using lots of trial and error, so if your telescope isn't well polar aligned then the above method won't work.

[peroni]

Great that you had some success with it, but it does help if you are not moving the scope a large amount in RA, as this is were the discrepancies begin to build up and you wind up with your intended target subject out of the field of view. In addition, the modern eyepieces that are now available, with a much wider FOV are also a distinct advantage using this method, than was the case some time ago

With the HEQ5 the RA ring only locks on 'zero' and so can have a tendency to stick as you move through large angles, thereby adding to the inaccuracy.

I only use my RA scale for polar alignment. There was a great post on Astroshed that detailed how to achieve accurate polar alignment simply by using the scale and a 'polarfinder' app to determine exactly when the last polar transit occurred.

For that purpose I use the top scale on the HEQ5 which reads 'right to left'. I also use a piece of electrical tape to prevent the RA scale from slipping/sticking when I move it. I had posted earlier the basics for the method I use. See below for a repeat:

The method I use was suggested by Dion over at Astronomy Shed (a youtube video was available). Basically,

1) level the tripod (this is very important for accurate tracking using just RA)

2) determine the last transit time for Polaris (I use Polar Finder app on Android)

3) Set the polar scope to have Polaris circle at bottom i.e. in transit

4) dial the last transit time into the RA settings circle (on my HEQ5 that is the top scale reading from right to left)

5) carefully rotate the RA axis back so it reads 0

If you are careful with the set up you can easily get 5 mins sub; I even tried 10 mins subs and got only slight star trails

Of course you'll only need this accuracy for astrophotography. If you are only visually observing you can ignore all the above.

[misck1]

Thanks to everyone that has been putting comments on and I it is good to know that this accuracy is only required for astrophotography.

However I still would like to clear it completely in my head which one to use.

My HEQ5 has its top scale reading from Right to Left.

I have included a You Tube link to the Astronomy shed set up which it describes which scale to use when setting up the mount

titled "Complete Mount And Scope Setup Part 1". He is using an NEQ6 mount. His RA ring is different to mine. His upper scale reads from Left to Right while my upper scale

is the opposite from Right to Left. To save time on looking through the whole You Tube video it is at 4 mins 55 secs into it that mentions in detail this point. When I saw this video I thought it was very clear until I saw Astro Baby's entry which was the complete opposite.......I am still very confused

[peroni]

I think it all depends what you are using the RA scale for. In this thread we have spoken about two uses:

• Polar alignment - In this case the top scale reading Right to Left works as that picks up the last Polaris transit time which is x hours in the past.
  
• Visual work - The bottom scale reads Left to Right and is the one used for reading off positions.
  

I can certainly confirm the Polar alignment works. I haven't tried visual so perhaps someone else with an HEQ5 can comment.

[skfboiler]

For those who are not sure about which scale to use, I suggest just simply trying it the next time observing using 2 easy naked eye stars. For example, slew the scope to Vega. Set your mount to Vega's coordinates which are RA 18h 36m and DEC +38d 47m. For the the RA, pick the scale you think might be the proper scale for your mount. For my mount in the Northern Hem. it is the top scale. Now quickly slew scope over to another easy star say Spica. Now read the RA scale where the coordinates which should be 13h 25m. If the scale is close to this then that is the scale you should use. I did this when I was hearing conflicting info between my mount instructions and other web sources and got immediate confirmation on which scale to use which is the top like the instructions say.

If you still have the mount instructions, which scale to use should be there. The manufacture knows their product more than anyone else, I hope.