46P, can't see

Mike Collins wrote:
StarDust wrote:
On Sunday, December 9, 2018 at 9:13:17 PM UTC-8, Chris L Peterson wrote:
On Sun, 9 Dec 2018 23:15:38 -0000 (UTC), Mike Collins

I just found it again from my back yard. Not perfect seeing. I can just
make out the Milky Way but only one star in the bowl of USA minor is
visible. I make it out to about 8 seconds of arc.

8 _minutes_ of arc?

That's very small?
Few people here saying the comet is very large.
Maybe the brightest part, the nucleus of the comet is 8 arc minutes?


I went by the side of the comet I could see. I used the apparent distance
between the nearby stars to estimate the size. It was exact where Luminos
predicted. From the darker sky site I used for my first observation it
might have been larger but you are observing from a city with light
pollution maybe worse than my village. Getting in my car to observe the
comet wasn’t an option last night due to early sampling of Christmas port.




I went to a darker sky area a couple of miles away and the comet was easy
in 10x50 binoculars but not visible with the naked eye. It was-1.5C and, as
common at this time of year in Norfolk fog was beginning to form over the
fields. I’m not good at estimating the brightness of extended objects like
comets but it was less bright than the Orion Nebula and M31 and about 10 or
12 minutes of arc.
The comet was also visible in the 8x40 binoculars I keep in the car for
wildlife and bird watching.

Paul Schlyter wrote:
On Sun, 9 Dec 2018 23:15:38 -0000 (UTC), Mike Collins
wrote:
I just found it again from my back yard. Not perfect seeing. I can
just make out the Milky Way but only one star in the bowl of USA minor
is visible.

Aren't you confusing seeing with transparency? Even with horrible
seeing the Milky Way will be easily visible if only the transparency
is good and the sky is dark.

He might have meant the verb (colloquial), not the noun (technical)

--
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

On Monday, December 10, 2018 at 2:56:02 PM UTC-8, Thomas 'PointedEars' Lahn wrote:
StarDust wrote:
I use C2A!
http://www.astrosurf.com/c2a/english/

ACK.

But to remind you, not every one is professor in math!

This is a stupid reaction. I am not a professor in math either. I happen
to study astrophysics (where this is repeated), but this is basic geometry
(how to calculate the arc length on the circumference of a circle) that you
learn in (high)school already.

I took some of my *precious* *free time* to explain it to you *for free*,
so that you can answer your question for an arbitrary celestial object for
yourself next time, and you are *complaining* about that?

And you still do not have the decency to introduce yourself to strangers
with your real name?

Tell me: Why should I read any of your postings again?

--
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

I just asked a simple question, how big is comet?
You answered with math calculations.
I know what arc minutes and angles are, used it all my life, I use to be a Journey man machinist and later mfg. engineer.

On Mon, 10 Dec 2018 07:43:48 -0800 (PST), StarDust
wrote:
In fraction one can use proximation, like the closest to .835 is
27/32 = 0.84375 or +1/32 away is 7/8 th!
I think, a carpenter, cook or plummer don't care about 1/32
difference? LOL!

Actually, 167/200 is even closer to 0.835 since it is exactly the
same. You cannot get closer than that...

If you care about a 1/32 difference depends on your demands of
precision. A cook may not care, but a precision mechanic will care.
If there's a mismatch of 1/32 cm between your eyepiece and your
eyepiece holder on your scope, you may be unable to insert your
eyepiece.

On Mon, 10 Dec 2018 19:11:54 -0000 (UTC), Mike Collins
wrote:
Paul Schlyter wrote:
On Mon, 10 Dec 2018 13:19:53 -0000 (UTC), Mike Collins
wrote:
I find it hard to format my brain in minutes and seconds of arc.
I
think of
degrees and decimal degrees.

Do you feel the same about time? So you use hours and decimals of
hours instead of hours, minutes and seconds? "I'll see you at
9.835"
- such a statement would be wilder most people...

When I wrote planetarium software in the 80s I used decimals and
only
converted to minutes and seconds for the final display.

That's natural. You want to use one unit instead of mixing
different
units internally in the software. For angles that unit could be
degrees. Or radians, so the built-in trig functions work without
any
need for unit conversion. For time, hours could be that unit. Or,
perhaps even better, days counted from some reference date. All
with
fractions to full machine precision of course. For display
purposes
you convert angles to whatever you want: degrees with decimals,
or
degrees and minutes with decimals, or degrees, minutes and
seconds
perhaps with decimals. The day count is converted to the calendar
date followed by hours, minutes and seconds. If there's any
input,
the opposite conversion needs to be done.


Ive grown up with time. But there arent 360 hours in a day.

No, but there are 360 degrees per day where one degree is 4 minutes
of time. You must distinguish minutes of time from minutes of arc
here. One hour is 15 degrees, that's how you convert RA in hours from
RA in degrees.

As far as date goes I spent a decade working in an environment
dominated by
what they called, incorrectly, Julian Date. Actually it was a
calendar with
January 1st as day 001 and incremented by one every day. We needed
to know
the day number to identify the dates of barcoded samples. This
would be as
useful and easy as months but would never be adopted.

That's the NASA variety of Julian Day Number, right? For each new
year, they start again with 001 on 1 Jan.

On Monday, December 10, 2018 at 10:32:15 PM UTC-8, Paul Schlyter wrote:
On Mon, 10 Dec 2018 07:43:48 -0800 (PST), StarDust

In fraction one can use proximation, like the closest to .835 is
27/32 = 0.84375 or +1/32 away is 7/8 th!
I think, a carpenter, cook or plummer don't care about 1/32
difference? LOL!

Actually, 167/200 is even closer to 0.835 since it is exactly the
same. You cannot get closer than that...

If you care about a 1/32 difference depends on your demands of
precision. A cook may not care, but a precision mechanic will care.
If there's a mismatch of 1/32 cm between your eyepiece and your
eyepiece holder on your scope, you may be unable to insert your
eyepiece.

But can you visualize 167/200?
That's what we talking about here!
1/32 cm is .012" it may be good enough to fit for an eyepiece! LOL!

On Tue, 11 Dec 2018 00:48:27 -0800 (PST), StarDust
wrote:
On Monday, December 10, 2018 at 10:32:15 PM UTC-8, Paul Schlyter
wrote:
On Mon, 10 Dec 2018 07:43:48 -0800 (PST), StarDust

In fraction one can use proximation, like the closest to .835
is
27/32 = 0.84375 or +1/32 away is 7/8 th!
I think, a carpenter, cook or plummer don't care about 1/32
difference? LOL!

Actually, 167/200 is even closer to 0.835 since it is exactly the
same. You cannot get closer than that...

If you care about a 1/32 difference depends on your demands of
precision. A cook may not care, but a precision mechanic will
care.
If there's a mismatch of 1/32 cm between your eyepiece and your
eyepiece holder on your scope, you may be unable to insert your
eyepiece.

But can you visualize 167/200?
That's what we talking about here!
1/32 cm is .012" it may be good enough to fit for an eyepiece! LOL!

I can draw a pie diagram showing 167/200 just as I can draw a pie
diagram showing 0.835.and a diagram showing 83.5% - those tree
diagrams will look exactly pthe same.

But you talked about preferring common fractions over decimal
fractions, however a decimal fraction can easily be converted into a
common fraction.

Perhaps you, by "common fraction" meant "a common fraction where the
denominator is an even, and not a too large, power of two"? That's a
small subset of all possible common fractions.

On Tuesday, December 11, 2018 at 10:46:48 PM UTC-8, Paul Schlyter wrote:
On Tue, 11 Dec 2018 00:48:27 -0800 (PST),
On Monday, December 10, 2018 at 10:32:15 PM UTC-8, Paul Schlyter
wrote:
On Mon, 10 Dec 2018 07:43:48 -0800 (PST), StarDust

In fraction one can use proximation, like the closest to .835
is
27/32 = 0.84375 or +1/32 away is 7/8 th!
I think, a carpenter, cook or plummer don't care about 1/32
difference? LOL!

Actually, 167/200 is even closer to 0.835 since it is exactly the
same. You cannot get closer than that...

If you care about a 1/32 difference depends on your demands of
precision. A cook may not care, but a precision mechanic will
care.
If there's a mismatch of 1/32 cm between your eyepiece and your
eyepiece holder on your scope, you may be unable to insert your
eyepiece.

But can you visualize 167/200?
That's what we talking about here!
1/32 cm is .012" it may be good enough to fit for an eyepiece! LOL!

I can draw a pie diagram showing 167/200 just as I can draw a pie
diagram showing 0.835.and a diagram showing 83.5% - those tree
diagrams will look exactly pthe same.

But you talked about preferring common fractions over decimal
fractions, however a decimal fraction can easily be converted into a
common fraction.

Perhaps you, by "common fraction" meant "a common fraction where the
denominator is an even, and not a too large, power of two"? That's a
small subset of all possible common fractions.

I meant common fractions, what we use in daily life, 1/2, 1/4, 3/8 etc...
Get it?
Carpenter don't use 167/200? 1/16" is good enough to cut a 2x4!
Try to measure 167/200" with a measuring tape from Home Depot, eh?
Some how you have difficulty understanding things?
Use to work as a machinist/tool maker for an optical shop, owner was a PhD chemist and sometime he had difficulty understanding simple layman terms.
He's mined was up in the clouds all the time!
Brain gets to complicated when receives too much education, different reality I guess?

On Tue, 11 Dec 2018 23:59:16 -0800 (PST), StarDust
wrote:
I meant common fractions, what we use in daily life, 1/2, 1/4, 3/8
etc...
Get it?
Carpenter don't use 167/200? 1/16" is good enough to cut a 2x4!
Try to measure 167/200" with a measuring tape from Home Depot, eh?
Some how you have difficulty understanding things?

I see. You are stuck with that outdated inefficient system of units
of feet and inches. While the rest of the world has gone metric, the
USA, Burma and Liberia prefer to stick to their outdated systems of
measurements.

No, I don't want to measure 167/200 inches with a measuring tape from
Home Depot which probably only measures inches anyway. I'd much
prefer to measure 0.835 cm with a **metric** ruler, measuring tape or
other measuring device. That's what we who live in the modern part of
the world do. On metric measuring devices the subdivisions are in
powers of 10, not powers of 2, so decimal fractions are then very
handy to use.

Welcome to the world outside the USA! Yes, it does exist! For real!!!

On Wednesday, December 12, 2018 at 12:17:29 AM UTC-8, Paul Schlyter wrote:
On Tue, 11 Dec 2018 23:59:16 -0800 (PST),

I meant common fractions, what we use in daily life, 1/2, 1/4, 3/8
etc...
Get it?
Carpenter don't use 167/200? 1/16" is good enough to cut a 2x4!
Try to measure 167/200" with a measuring tape from Home Depot, eh?
Some how you have difficulty understanding things?

I see. You are stuck with that outdated inefficient system of units
of feet and inches. While the rest of the world has gone metric, the
USA, Burma and Liberia prefer to stick to their outdated systems of
measurements.

No, I don't want to measure 167/200 inches with a measuring tape from
Home Depot which probably only measures inches anyway. I'd much
prefer to measure 0.835 cm with a **metric** ruler, measuring tape or
other measuring device. That's what we who live in the modern part of
the world do. On metric measuring devices the subdivisions are in
powers of 10, not powers of 2, so decimal fractions are then very
handy to use.

Welcome to the world outside the USA! Yes, it does exist! For real!!!

Also England and Australia use the old system!
They even drive in the left side of the road there too! LOL!
Now days measuring tapes has both system of units, but still the inch is the mostly used, not metric!
Progress , I guess!
If you buy an American car and like to be a weekend mechanic, you have to buy tons of tools, in fractions units, 1/2" wrench or 1/4" drill bit or 16 oz. hammer etc...
Crazy, but more profit in selling tools!