I've got a great new astronomy hobby!

I've got a great new astronomy hobby! It's figuring out how my equitorial
telescope mount works. I thought I had it all figured out then I discovered
that the right ascension ring moves independently, which throws half of my
understanding out the window.

With the sky moving, the clock drive turning the ring, and the ring itself
turning, I just know this will take me forever to understand. This could be a
lifetime pursuit! I love a challenge.

"Bruce W...1" wrote in message
...
I've got a great new astronomy hobby! It's figuring out how my equitorial
telescope mount works. I thought I had it all figured out then I
discovered
that the right ascension ring moves independently, which throws half of my
understanding out the window.

With the sky moving, the clock drive turning the ring, and the ring itself
turning, I just know this will take me forever to understand. This could
be a
lifetime pursuit! I love a challenge.

I know what you mean. It's not enough for me to know something works, I want
to understand how and why it works.

"Bruce W...1" wrote in alt.astronomy:

I've got a great new astronomy hobby! It's figuring out how my
equitorial telescope mount works. I thought I had it all figured out
then I discovered that the right ascension ring moves independently,
which throws half of my understanding out the window.

With the sky moving, the clock drive turning the ring, and the ring
itself turning, I just know this will take me forever to understand.
This could be a lifetime pursuit! I love a challenge.


The RA ring moves independently from the mount because you can turn your
scope over the west side as well as over the east side, yet pointing it
at the same point at the sky. So it has to be possible to turn it into
the opposite direction.

The ring is not for indicating where your telescope is pointing at, it's
a simple and ancient GOTO function: for locating/finding objects from a
fixed point you know.

Release the clutches of your motor drives, point the scope at a familiar
star, check if declination is okay - as it's fixed (if not, "polar
alignment blues" again) set the RA ring to the RA of the star, and look
up the coordinates of the object you want to locate.

Now move both the RA and DEC telescope axis to the coordinates as
indicated on both rings and lock the scope.

Look at the rings, not at the sky. If the pointer on both axis points to
the coordinates of the object of your liking, it should be in the FOV.
A crude but (with proper polar alignment) a often very effective
mechanical GOTO function )

Now you can start following with your motor drives again.

If you have a fast motor drive, you could also use the motors to guide
the telescope to the right coordinates.

If you have a computerized hand controller with a database or a RA/DEC
input function, you should bang your head against the wall and forget
about the rings altogether.

--
CeeBee


Uxbridge: "By God, sir, I've lost my leg!"
Wellington: "By God, sir, so you have!"


Google CeeBee @ www.geocities.com/ceebee_2

CeeBee wrote:

The RA ring moves independently from the mount because you can turn your
scope over the west side as well as over the east side, yet pointing it
at the same point at the sky. So it has to be possible to turn it into
the opposite direction.

The ring is not for indicating where your telescope is pointing at, it's
a simple and ancient GOTO function: for locating/finding objects from a
fixed point you know.

Release the clutches of your motor drives, point the scope at a familiar
star, check if declination is okay - as it's fixed (if not, "polar
alignment blues" again) set the RA ring to the RA of the star, and look
up the coordinates of the object you want to locate.

Now move both the RA and DEC telescope axis to the coordinates as
indicated on both rings and lock the scope.

Look at the rings, not at the sky. If the pointer on both axis points to
the coordinates of the object of your liking, it should be in the FOV.
A crude but (with proper polar alignment) a often very effective
mechanical GOTO function )

Now you can start following with your motor drives again.

If you have a fast motor drive, you could also use the motors to guide
the telescope to the right coordinates.

If you have a computerized hand controller with a database or a RA/DEC
input function, you should bang your head against the wall and forget
about the rings altogether.

--
CeeBee

Uxbridge: "By God, sir, I've lost my leg!"
Wellington: "By God, sir, so you have!"

Google CeeBee @ www.geocities.com/ceebee_2
================================================== ==============

I just devoted heavy thought and research to this matter.

My mount is a Vixen Super Polaris and I am in the northern hemisphere. Assuming
it is properly alligned, in order to view anything west of the north star and
have the right number shown on the ascension ring (setting circle) then the tube
is upside down on the mount. That is the counterweight would be above the
telescope.

This all makes perfect sense but this is bull****. Why didn't Vixen just put
two sets of numbers on the ascension ring? I can do the math and subtract
twelve hours to achieve the same affect. But I'm inclined to add some labels to
the ascension ring to avoid the constant math and avoid having the tube inverted
on the mount. Does th1Ù•ake sense? Is this a reasonable course of action?

Thanks.

"Bruce W...1" wrote in alt.astronomy:

I just devoted heavy thought and research to this matter.


Good, grasshopper. This is the first step to the dawn of knowledge.


My mount is a Vixen Super Polaris and I am in the northern hemisphere.
Assuming it is properly alligned, in order to view anything west of
the north star and have the right number shown on the ascension ring
(setting circle) then the tube is upside down on the mount. That is
the counterweight would be above the telescope.


No. The RA circle isn't fixed, so it doesn't indicate absolute values.
If you swing the scope to the left, your RA circle might indicate 23h,
but swinging it to the right, it might show 11h, while pointing at the
same object in the sky. You can turn it back however, else there
wouldn't be a proper use for the circles.

The RA and Decl. circles are _NOT_ an indication of "what point in the
sky am I looking at".
The setting circles define "distance between a well known object and the
an object in it's vicinity that you want to observe".

This all makes perfect sense but this is bull****.

Yes, you are right. Start using them as it's meant to be and you'll be
amazed.


Why didn't Vixen
just put two sets of numbers on the ascension ring?

One is enough, if you know how to use it properly. But I already
suggested that


I can do the math
and subtract twelve hours to achieve the same affect. But I'm
inclined to add some labels to the ascension ring to avoid the
constant math and avoid having the tube inverted on the mount. Does
th1Ù•ake sense? Is this a reasonable course of action?


Let's take an example.

Your mount is properly aligned. Yes it is. If not - do so.

Now you want to observe the M15, a nice globular in the vicinity of
Pegasus. It's halfway between Altair and Markab, and the question is:
which star to use. Say it's now twelve 'o clock here, and Markad is in
the South-southeast sky while Altair is high up south southwest. But
Altair is much brighter so we're going to use it.

Point your scope to Polaris, and swing your tube to the east. Now turn
the mount towards you over the west and point it up to Altair. That
comes close with that mount. Maybe it doesn't even work. Forget it.

So let's swing the mount to the other side, swinging it towards the
east. The tube is now to the left of the mount from your viewpoint
(you're looking towards the south, Polaris behind you, and you're in
front of your scope).

That looks better. The scope is a bit higher than your counterweight.
Now take care and get Altair in your field of view. As much in the
middle as possible. Use a low magnification eyepiece. Lock the scope,
start the motor drive.

Look at the Declination circle. It's fixed, you can't turn it. It
indicates something like +9 degrees, and with the vernier on the scale
you could even go down to a quarter of a degree.

If it's very close to Decl. 9 degrees, you're the man. You can proceed.
If it's not, realign your scope. Back to the grunt work.

Look at the RA circle. It's gibberish. It tells you some random RA, but
what the heck. Forget it. Now look up the RA of Altair. That's 19 h 51
min.
Turn the RA circle (not the scope!) until the pointer on the mount
points at 19h51m, using the vernier to get that one minute right.

You properly locked on Altair.
Now don't take too long, as the mount continues to turn with the motor
drives on, but the RA circle is not, and is starting to lag behind
rapidly.
So a quick look to the coordinates of the M15: Decl +12 degree 11
minutes and RA 21 h 30 minutes.

Now unlock the Declination axis and point the scale divider on the mount
to +12 degr. 11 minutes, with the vernier you can get to 12 15 exactly,
that's close enough.
Lock the axis. The Declination is okay.

Now unlock the RA axis and swing the scope until the scale divider above
the RA circle which points at 19 51 for the moment, as you pointed to
Altair. Now swing it further until it reads 21h 30h. exactly.
Lock the axis. The RA is okay.

Move your body behind the scope and look through the eyepiece: you
should now have M15 in your FOV. You have located M15 with a mechanical
GOTO function.

Again: the better your polar alignment, the better your result. If you
don't see M15, your scope is probably not aligned properly enough. You
should search the direct vicinity of your FOV and see if M15 is around,
or re-align the telescope for better results.


So: if you want to locate an object: use a known and bright reference
star in the vicinity of that object. Don't point at Altair to find the
M51 but use Eta Ursae Majoris (the tail star of the Big Dipper) instead.
Don't use Eta Ursae Majoris to locate the M57, the Ring Nebula, but use
Vega. Keep the "swings" low.

Good luck.


--
CeeBee


Uxbridge: "By God, sir, I've lost my leg!"
Wellington: "By God, sir, so you have!"


Google CeeBee @ www.geocities.com/ceebee_2

CeeBee wrote:

"Bruce W...1" wrote in alt.astronomy:


Good, grasshopper. This is the first step to the dawn of knowledge.

No. The RA circle isn't fixed, so it doesn't indicate absolute values.
If you swing the scope to the left, your RA circle might indicate 23h,
but swinging it to the right, it might show 11h, while pointing at the
same object in the sky. You can turn it back however, else there
wouldn't be a proper use for the circles.

The RA and Decl. circles are _NOT_ an indication of "what point in the
sky am I looking at".
The setting circles define "distance between a well known object and the
an object in it's vicinity that you want to observe".

Yes, you are right. Start using them as it's meant to be and you'll be
amazed.

One is enough, if you know how to use it properly. But I already
suggested that

Let's take an example.

Your mount is properly aligned. Yes it is. If not - do so.

Now you want to observe the M15, a nice globular in the vicinity of
Pegasus. It's halfway between Altair and Markab, and the question is:
which star to use. Say it's now twelve 'o clock here, and Markad is in
the South-southeast sky while Altair is high up south southwest. But
Altair is much brighter so we're going to use it.

Point your scope to Polaris, and swing your tube to the east. Now turn
the mount towards you over the west and point it up to Altair. That
comes close with that mount. Maybe it doesn't even work. Forget it.

So let's swing the mount to the other side, swinging it towards the
east. The tube is now to the left of the mount from your viewpoint
(you're looking towards the south, Polaris behind you, and you're in
front of your scope).

That looks better. The scope is a bit higher than your counterweight.
Now take care and get Altair in your field of view. As much in the
middle as possible. Use a low magnification eyepiece. Lock the scope,
start the motor drive.

Look at the Declination circle. It's fixed, you can't turn it. It
indicates something like +9 degrees, and with the vernier on the scale
you could even go down to a quarter of a degree.

If it's very close to Decl. 9 degrees, you're the man. You can proceed.
If it's not, realign your scope. Back to the grunt work.

Look at the RA circle. It's gibberish. It tells you some random RA, but
what the heck. Forget it. Now look up the RA of Altair. That's 19 h 51
min.
Turn the RA circle (not the scope!) until the pointer on the mount
points at 19h51m, using the vernier to get that one minute right.

You properly locked on Altair.
Now don't take too long, as the mount continues to turn with the motor
drives on, but the RA circle is not, and is starting to lag behind
rapidly.
So a quick look to the coordinates of the M15: Decl +12 degree 11
minutes and RA 21 h 30 minutes.

Now unlock the Declination axis and point the scale divider on the mount
to +12 degr. 11 minutes, with the vernier you can get to 12 15 exactly,
that's close enough.
Lock the axis. The Declination is okay.

Now unlock the RA axis and swing the scope until the scale divider above
the RA circle which points at 19 51 for the moment, as you pointed to
Altair. Now swing it further until it reads 21h 30h. exactly.
Lock the axis. The RA is okay.

Move your body behind the scope and look through the eyepiece: you
should now have M15 in your FOV. You have located M15 with a mechanical
GOTO function.

Again: the better your polar alignment, the better your result. If you
don't see M15, your scope is probably not aligned properly enough. You
should search the direct vicinity of your FOV and see if M15 is around,
or re-align the telescope for better results.

So: if you want to locate an object: use a known and bright reference
star in the vicinity of that object. Don't point at Altair to find the
M51 but use Eta Ursae Majoris (the tail star of the Big Dipper) instead.
Don't use Eta Ursae Majoris to locate the M57, the Ring Nebula, but use
Vega. Keep the "swings" low.

Good luck.

--
CeeBee

Uxbridge: "By God, sir, I've lost my leg!"
Wellington: "By God, sir, so you have!"

Google CeeBee @ www.geocities.com/ceebee_2
================================================== ==============

Just did a couple more experiments.

You are correct of course. It's difficult for me to leave the absolute
positioning mindset.

And indeed I can return to this after the RA ring is calibrated and the clock
drive stays engaged.

Thanks for your input.