The UTC thread

It should be quite clear to anyone in astronomy by now that UT or UTC or GMT
is Universal Time. Those who don't have any concept of this designation
should
really consider just what level of amateur they really are. Astronomical
observing
is completely dependent on timing. It is just easier if people report
observations of any kind
in UTC. People should know what their local offset is whether it is
Daylight or standard, PDT, MST, MDT,EDT,Europe, China or Antartica!!

For one thing, to do a polar alignment, you have to know your local time
meridian offset and whether you
are east or west of it.

For those of us who do orbital mechanics for a living, UT, UTC and GMT is
just the beginning... But you don't need to know any of those things to
discover a comet, make a new observation on a variable star, discover a new
supernova, etc. Let's not degrade other people because making time
conversions makes you irritable...

--

Clear Skies,

Chuck

"MikeThomas" wrote in message
news:6bqTc.20328$fz2.3652@edtnps89...
It should be quite clear to anyone in astronomy by now that UT or UTC or
GMT
is Universal Time. Those who don't have any concept of this designation
should
really consider just what level of amateur they really are. Astronomical
observing
is completely dependent on timing. It is just easier if people report
observations of any kind
in UTC. People should know what their local offset is whether it is
Daylight or standard, PDT, MST, MDT,EDT,Europe, China or Antartica!!

For one thing, to do a polar alignment, you have to know your local time
meridian offset and whether you
are east or west of it.

MikeThomas wrote:

It should be quite clear to anyone in astronomy by now that UT or UTC or GMT
is Universal Time. Those who don't have any concept of this designation
should
really consider just what level of amateur they really are. Astronomical
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^
observing
is completely dependent on timing. It is just easier if people report
observations of any kind
in UTC. People should know what their local offset is whether it is
Daylight or standard, PDT, MST, MDT,EDT,Europe, China or Antartica!!

For one thing, to do a polar alignment, you have to know your local time
meridian offset and whether you
are east or west of it.



Please tell us, Mike, what level of amateur are YOU?

Regards,
Etok

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While reading in the bathroom on Sat, 14 Aug 2004 15:26:58 GMT, I saw
that "MikeThomas" had written:

For one thing, to do a polar alignment, you have to know your local time
meridian offset and whether you
are east or west of it.

????????????

To do a polar alignment, I line up on the pole star. Time has nothing
to do with it, although knowing how to put my 'scope in its "home"
position is critical.

For a planisphere, with the amount of light pollution around here, I
can be as much as an hour off without screwing up my ability to find
something in the sky.

For using Autostar on my goto (ETX-125), accuracy to within a couple
of minutes is adequate. You do have to know your time zone, and
whether you're in daylight or standard time, but even the exact
long-lat isn't necessary.

I do have the knowledge and capability to be more precise than that
but, as someone else said, we're not astronauts, and astronomy isn't
rocket science. The night sky doesn't move that fast and a
wide-enough FOV will give you plenty of margin.


--------------
Beady's Corollary to Occam's Razor: "The likeliest explanation of any phenomenon is almost always the most boring one imaginable."


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On Sat, 14 Aug 2004 14:08:01 -0400, John Beaderstadt wrote:

I do have the knowledge and capability to be more precise than that
but, as someone else said, we're not astronauts, and astronomy isn't
rocket science. The night sky doesn't move that fast and a
wide-enough FOV will give you plenty of margin.

My telescope pointing accuracy is around 30 arcsec. That corresponds to 2
seconds of time error. Since I don't sync my scope, but rely on an accurate time
and pointing model, I depend on very accurate time measurement. Of course, if
you are working visually, and syncing you scope to calibrate the RA, than you
don't need much accuracy at all. For occultation timing, a second is a large
error.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

John Beaderstadt wrote:
While reading in the bathroom on Sat, 14 Aug 2004 15:26:58 GMT, I saw
that "MikeThomas" had written:

For one thing, to do a polar alignment, you have to know your local
time
meridian offset and whether you
are east or west of it.

????????????

To do a polar alignment, I line up on the pole star. Time has nothing
to do with it,

Personally, I try to line up on the North Celestial Pole (since I live in
the northern hemisphere). While time affects the position of Polaris, it
does not affect the position of the North Celestial Pole (ignoring
precession). If you use Polaris as a polar alignment aid, you need to know
the time of day, unless your error tolerance is big enough.

although knowing how to put my 'scope in its "home"
position is critical.

That is not critical at all in my case, as I use drift alignment using a
german equatorial mount.

Clear skies
Carsten A. Arnholm
http://arnholm.org/
N59.776 E10.457

While reading in the bathroom on Sat, 14 Aug 2004 21:18:47 +0200, I
saw that "Carsten A. Arnholm" had written:

If you use Polaris as a polar alignment aid, you need to know
the time of day, unless your error tolerance is big enough.

Which is the big advantage of a goto scope. For polar alignment, I
just need to be in the ballpark; then I do the "Easy" two-star
alignment and I'm set for the evening.



--------------
Beady's Corollary to Occam's Razor: "The likeliest explanation of any phenomenon is almost always the most boring one imaginable."


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"John Beaderstadt" wrote in message
...
While reading in the bathroom on Sat, 14 Aug 2004 21:18:47 +0200, I
saw that "Carsten A. Arnholm" had written:

If you use Polaris as a polar alignment aid, you need to know
the time of day, unless your error tolerance is big enough.

Which is the big advantage of a goto scope. For polar alignment, I
just need to be in the ballpark; then I do the "Easy" two-star
alignment and I'm set for the evening.


What is the two star alignment?

MikeThomas wrote:
"John Beaderstadt" wrote in message
...

While reading in the bathroom on Sat, 14 Aug 2004 21:18:47 +0200, I
saw that "Carsten A. Arnholm" had written:


If you use Polaris as a polar alignment aid, you need to know
the time of day, unless your error tolerance is big enough.

Which is the big advantage of a goto scope. For polar alignment, I
just need to be in the ballpark; then I do the "Easy" two-star
alignment and I'm set for the evening.



What is the two star alignment?


Easy two star alignment is a feature of Autostar (Meade) telescopes. I'd
imagine there are similar features with other goto systems. For example,
I've seen Vixen mounts which can do multiple star alignment (same
principle, but more stars and therefore arguably more accuracy).

Basically, you level the scope and point it (roughly) North to give it
an idea of where it's pointing. Autostar then picks out two stars which
are used to align the scope (or you can pick them yourself from a list).
During alignment, the scope slews to the chosen stars, which you must
manually centre in the eyepiece. Once it knows where those two
"reference point" stars are, the idea is that it can figure out the rest
itself. There's also a one star alignment method, which is similar but
inherently less accurate.

The main advantage is that if your "best guess" at North is off, you can
still align the scope reasonably accurately, even without using Polaris
as a reference point.

MikeThomas:
is completely dependent on timing. It is just easier if people report
observations of any kind in UTC. People should know what their local
offset is whether it is Daylight or standard, PDT, MST, MDT, EDT,
Europe, China or Antartica!!

So in what time zone(s) are the north and south poles located? Both
points are on every meridian and on no meridian.

For one thing, to do a polar alignment, you have to know your local time
meridian offset and whether you are east or west of it.

I drift-align my Questar without reference to any time at all. After
the alignment I need to know the R.A. of a star -- any visible star --
in order to move my R.A. setting circle to the correct position as a
reference for finding other objects of known R.A. But I still don't
need to know what time it is in Tuguegarao* or Shibam-Kawkaban**, or,
indeed, where on earth I am.

Davoud

* generally poor for deep sky, good for solar system
** great skies, but a dangerous place

--
usenet *at* davidillig dawt com