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Old 04-10-2012, 06:32 AM
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lhansen (Lars)
My God! Its full of stars

lhansen is offline
 
Join Date: Dec 2005
Location: Dunkeld, NSW
Posts: 561
Thanks Gary

I should be able to turn this into a spreadsheet and import the export file.

I'll have a bash

Cheers

Lars
Quote:
Originally Posted by gary View Post
Lars, you are most welcome.



New_Scope_RA = normalized(Old_Scope_RA + 180 degrees)
New_Scope_Dec = normalized(180 - Old_Scope_Dec)

Since the RA positions are in hh:mm:ss format, you first need to convert them to
decimal hour format (i.e. hh.d ....).

To do that,
decimal_hours = h + m/60 + s/3600

So for example, star 26's scope RA was 22:31:50.
Therefore in decimal hours, 22 + 31/60 + 50/3600 = 22.5306.
You can also perform that conversion conveniently online here -
http://www.springfrog.com/converter/decimal-time.htm

We then need to convert this to degrees by multiplying by 15.
Therefore 22.5306 * 15 = 337.9583 degrees.
We add 180 degrees to this, so that 337.9593 + 180 = 517.9593.
By "normalize" we mean here to keep it in the range of 0 to 360 degrees.
Since our number is greater than 180 degrees, we can subtract an entire 360 degrees
to get 517.9583 - 360 = 157.9583.
We now need to convert this back to decimal hours, so we divide by 15.
157.9583/15 = 10.5306
We now want to convert this to hh:mm:ss format
Using http://www.springfrog.com/converter/decimal-time.htm to convert back -
the result is 10:31:50

For Dec, we need to convert -57:02:32 to decimal degrees, being mindful of
the minus sign. Conveniently, you can use this web site -
http://data.aad.gov.au/aadc/calc/dms_decimal.cfm
The result is -57.0422.
We now compute the New_Scope_Dec = 180 - -57.0422 = 237.0422.
In the case of Dec, to normalize, if the value is greater than 180, we
will subtract 360 degrees. If it is less than -180, we will add 360 degrees.
Therefore 237.0422 - 360 = -122.9578.
We then need to convert that back to dd:mm:ss format.
Conveniently, you can use this web site -
http://data.aad.gov.au/aadc/calc/decimal_dms.cfm
the result is -122:57:28

So you then hand edit the Scope RA and Scope Dec fields for star 26
and enter the values 10 31 50 and -122 57:28
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