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David Kennedal Precision Planet and Star Locator

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#1 Harry Jacobson

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Posted 27 October 2010 - 01:49 AM

The most useful planisphere for me is Precision Planet and Star Locator by David Kennedal. It's truly a shame Sky and Telescope stopped carrying this star wheel.

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The unique feature of this planisphere which gives it great utility (which I've not seen on any other starwheel) is the alt-azimuth grid printed on the view window (the spider web in the image). Objects in the view window can be located to within 5 or 10 degrees! No other starwheel has that kind of accuracy.

When I want to track the location of an object through the night, nothing works faster and more easily then Precision Planet and Star Locator. It's always ready and does not require technology: Though I've come to rely on SkyTools 3 when I'm at my computer I'm not always at my computer; Precision Planet and Star Locator is more portable and always ready for work.

FWIW, I found two used copies offered on Amazon. One was about $60, the other about $240! I've had my copy since the mid-1990's; if I ever have to replace it.........

Harry

#2 GlennLeDrew

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Posted 27 October 2010 - 07:01 PM

Some additional, unique features of this neat device making it work kind of like a slide rule...

It uses an additional couple of disks, one having a printed single spiral line, the other having a 2-3mm wide slot running N-S. You dial in the coordinates for some object like the Sun, Moon, planet or comet (or even a DSO), and these windows together make for a little diamond-shaped black spot in the correct location in the sky.

If you've dialed in the Sun's position, you can find the times of civil and astronomical trilight via the two pairs of transparent arcs at their appropriate atlitude below the horizon.

I got mine back about 1990, and its window has unfortunately gone rather yellow with age.

#3 RobFriedman

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Posted 20 October 2012 - 10:33 PM

I'm looking for one!!! i have a 40-50 one and a lower one.. 30-40 which i never use.. I do need to replace the one i use... please any help on this

#4 Rick Woods

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Posted 22 October 2012 - 06:29 PM

How is it a precision planet finder? Is each edition only good for a certain number of years, or what?

I find planispheres in general to be very handy. I keep one in the observatory, and another in my little briefcase of portable astro doc & stuff. (I also keep a camera flash attachment in there so I can fire photon torpedoes from my scope when the observing starts petering out.)

I also still have my old Griffith Observatory Astrorama (a cardboard planisphere from the early 60's), which is old and crumbly now and stays in a safe place. :D

#5 beatlejuice

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Posted 22 October 2012 - 10:46 PM

How is it a precision planet finder? Is each edition only good for a certain number of years, or what?



As Glen detailed above, you can dial in the co-ordinates of any object to arrive at an approximate location. It is actually quite unique and I am sorry that mine got worn out and discarded a few years ago.

Eric

#6 Rick Woods

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Posted 22 October 2012 - 11:38 PM

How is it a precision planet finder? Is each edition only good for a certain number of years, or what?



As Glen detailed above, you can dial in the co-ordinates of any object to arrive at an approximate location. It is actually quite unique and I am sorry that mine got worn out and discarded a few years ago.

Eric


Well, sure; but, if you have coordinates to dial in, then you already have a location. But, how does that work for planets, whose positions (and coordinates) change drastically from month to month and year to year?

#7 beatlejuice

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Posted 23 October 2012 - 01:03 AM

Well, sure; but, if you have coordinates to dial in, then you already have a location. But, how does that work for planets, whose positions (and coordinates) change drastically from month to month and year to year?


This was created before the computer age really took over. Novice stargazers who perhaps had no idea where an object(planet) was or had little directional aptitude when it came to RA and Dec could; with reasonably current co-ordinates (as were found in S&T or Astronomy) locate the general area of the sky to find said object at a certain time. A bright planet like Jupiter or Saturn would then stand out as being what it was rather then just another star.
My greatest use was for moonrise,moonset and times for the beginning or ending of astronomical twilight.
But I do think that the target market was novice oriented in general.

Eric

#8 bumm

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Posted 23 October 2012 - 03:50 PM

One of the things I really find handy about Kennedal's planisphere is how you can set it for Daylight Saving Time or Regular Time, and also correct it for your distance from the center of your time zone... When it says something is on the meridian, it's right there...

#9 bumm

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Posted 23 October 2012 - 04:33 PM

OH! Like Eric said, those two little slots off the horizon circle... You can set the indicator to show the position of the sun and see when the sun hits the horizon, astronomical twilight, and (most important,) complete darkness.

#10 RobFriedman

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Posted 24 October 2012 - 12:57 PM

I used it with my Astroscan to find items. I had a book or guide that gave the RA and DEC and I would dial it in and it would show where it was. Think of the Kennedal disk as an analogue computer. all this was PRE GoTo days.. AND it forced you to learn where items were and what RA and DEC was. I see the GoTo scopes.. which is a nice idea.. but while newcomers see nice items.. do they learn the sky?

#11 RobFriedman

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Posted 25 November 2012 - 04:28 PM

btw, I have a 30 degree Precision Planet and Star Locator that I am willing to trade for either the 30-60 version without the alt-az grid or possibly another 40 degree?

if not I am looking for one and I would love to hear from anyone who has one they want to sell or donate

Rob






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