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View Full Version : PROTRACTORS FOR MEASURING DEGREES IN SKY



Sam5
2004-Jan-14, 02:23 PM
Ok folks, here are a couple of printable protractors and an astrolabe.

You can use these for finding satellites, iridium flares, and other neat things in the sky.

The first one you can used for finding angles off the horizon.

Aim the base of the protractor level with the ground you are standing on, and then 90 degrees is straight up. With this you can tell what 10 degrees, 20 degrees, etc. are above the horizon. 90 degrees is directly overhead. You can copy this image to a Word program to enlarge or reduce the size of it.

180 DEGREE PROTRACTOR (http://www.lawrencegoetz.com/protrac.gif)

Here is a 360 degree protractor. You can use it for the same thing, but you can also use it for finding Azimuth directions around the globe. Place the paper flat with the ground you are standing on, then aim the inner “0” to the North and read the inner circle of numbers. 180 degrees on the inner circle will aim South. 90 degrees will be East. 270 degrees will be West. Copy the image to Word program document to enlarge or reduce the size.

LARGE IMAGE 360 (http://www.dick-blick.com/items/554/54/55454-1006-3ww.jpg)

ORDER A PLASTIC VERSION OF THE 360 (http://www.dickblick.com/zz554/54/products.asp?param=0&ig_id=1627)

Here is an old astrolabe version:

astrolabe version (http://www.rootsweb.com/~mosmd/astrolb.htm)

Sam5
2004-Jan-14, 03:33 PM
GMT main website, lots of good time stuff:

GMT WEBSITE WORLD TIME ZONES (http://wwp.greenwichmeantime.com/home.htm)

Scroll down that webpage and click on the “Major US Cities”, “Major Canadian Cities”, and “Major European Cities” to get local time-zone clocks.

Scroll down and click on “REST OF WORLD” for local world-wide time-zone clocks.

Use this 24 – 12 hour conversion chart if you need it (short PDF download):

24 TO 12 HR CONVERSION CHART (http://www.reginatransit.com/rts_download/pdf_24_hour_chart.pdf)

AUSTRALIA TIME INFO, CLICK ON MAP FOR DETAILS:

AUSTRALIA CLOCKS (http://wwp.greenwichmeantime.com/time-zone/australia/index.htm)

World time zone map, local hours at bottom of picture:

WORLD TIME ZONE MAP (http://www.travel.com.hk/region/timezone.htm)

World time conversion chart, from UT, UTC, and GMT to your local time:

WORLD TIME CONVERSION CHART (http://www.souledout.org/nightsky/time/ut.html)

Charlie in Dayton
2004-Jan-15, 06:49 AM
Sam5, there's an easier way to do this...it's called a sextant...

Go to eBay and do a search for 'Davis sextant'...the Mark 3 model is the beginner's model, it's usually fairly cheap (yet still accurate), and if it's still got all it's stuff, has an excellent instruction manual and a padded case.

There are two on eBay now, one for less than $15 and one for less than $6 (like I said, they're the beginner's model, all plastic, yet they're accurate enough to use at sea).

The one I scored had an artificial horizon so I can practice out on the front walk to do accurate sun sights.

Wanna knock 'em dead at that star party? When someone asks the altitude of that star over there, whip out your sextant and tell 'em... 8-[

Sam5
2004-Jan-15, 04:09 PM
Sam5, there's an easier way to do this...it's called a sextant...

Go to eBay and do a search for 'Davis sextant'...the Mark 3 model is the beginner's model, it's usually fairly cheap (yet still accurate), and if it's still got all it's stuff, has an excellent instruction manual and a padded case.

Wanna knock 'em dead at that star party? When someone asks the altitude of that star over there, whip out your sextant and tell 'em... 8-[

Here’s an Ebay search page for “Davis Sextant”:

LINK TO EBAY (http://search.ebay.com/search/search.dll?cgiurl=http%3A%2F%2Fcgi.ebay.com%2Fws%2 F&krd=1&from=R8&MfcISAPICommand=GetResult&ht=1&Sor tProperty=MetaEndSort&query=davis+sextant)

I think a 360 degree protractor would be best for finding satellites, since the satellite positions are given in degrees, and anyone can just print out the paper protractors. But a sextant could be used for telling the positions of stars or planets after they are found.

Charlie in Dayton
2004-Jan-16, 06:14 AM
And sextants read out in degrees altitude above the horizon...remember, I said I had a Davis Mark 3...and it's totally acceptable to give a star's current position az/alt in degrees...hence the sextant...what did you think they did navigational star shots with, anyway?

Sam5
2004-Jan-16, 06:29 AM
And

I was talking about satellite finding, not star position calculating.

Charlie in Dayton
2004-Jan-16, 07:36 AM
Unless you're talking geostationary satellites, a protractor or a sextant won't do you beans worth of good. H3ll, you'd need a go-to scope moved by a small-block Chevy and Halibrand QuickChange gear train. Them LEO boogers move real fast, and conventional go-to motors don't come anywhere near being fast enough to track it. I've watched more than one satellite go by in binoculars, and we're talking between three and seven minutes horizon to horizon, depending on orbit altitude.

Sam5
2004-Jan-16, 05:15 PM
Unless you're talking geostationary satellites, a protractor or a sextant won't do you beans worth of good.

When they give satellite sighting positions such as Altitude 13 degrees, Azimuth 192 degrees SSW, I prefer using a protractor to find the satellite.

I use a simple protractor to find the ISS, based on the altitude and the N,S,E,W directions given on the NASA website.

Sam5
2004-Jan-16, 05:21 PM
Charlie in Dayton,


This kind of protractor gives altitude in degrees off the horizon:

http://www.lawrencegoetz.com/protrac.gif

This kind gives 360 degree azimuth position:

http://www.dick-blick.com/items/554/54/55454-1006-1ww.jpg