Clarified installation

INSTALL.md

@@ -0,0 +1,9 @@
+# Installation
+
+The code is installed using just a file copy of the python (.py) files to a suitable directory. No additional libraries are necessary. 
+Python 3.11 is required. 
+
+The python script could be installed in [PyDroid](https://play.google.com/store/apps/details?id=ru.iiec.pydroid3) to allow for use on a mobile phone 
+(with no need for internet access). 
+
+You are advised to make copies of the supplied samples starfixdata.chicago.py or starfix.sea.py to support your workflow and observations. 

README.md

@@ -14,14 +14,13 @@
 
 ![US Navy training in celestial navigation](pics/us-navy.jpg "US Navy Training in Celestial Navigation")
 
-Contains a simple python script to be used for [celestial navigation](https://en.wikipedia.org/wiki/Celestial_navigation). <br>
-Sights have to be obtained using a sextant, a nautical almanac and an accurate clock. <br>
-The python script takes care of the **sight reduction**. For two sights you will get two possible coordinates. For three or more sights you will get one coordinate (calculated as a mean value). 
+This project contains a simple python script to be used for [celestial navigation](https://en.wikipedia.org/wiki/Celestial_navigation) togheter with some demos and documentations. <br>
+Sights (altitude measurements) have to be obtained using a sextant, a nautical almanac and an accurate clock. <br>
+The python script takes care of the **sight reduction** (conversion to estimated location on Earth). For two sights you will get two possible coordinates. For three or more sights you will get one coordinate (calculated as a mean value). 
 
-The script supports **stationary** observations, i.e. when observations are made from a single position, typically using multiple sights. There is also support for **dead reckoning** observations, typically at sea on a moving ship. See section 3 below for more information. 
+The script supports **stationary** observations, i.e. when observations are made from a single position, typically using multiple sights. There is also support for **dead reckoning** observations, typically at sea on a moving ship. This also needs a working compass and a chip log or similar. See section 3 below for more information. 
 
-The python script only uses basic libraries (no numpy or similar) and could be installed in [PyDroid](https://play.google.com/store/apps/details?id=ru.iiec.pydroid3) to allow for use on a mobile phone 
-(with no need for internet access). Python 3.11 is required.
+For more information on installation see [here](INSTALL.md).
 
 A [digital version of the Nautical Almanac](NAtrad(A4)_2024.pdf) for 2024 is included in this repository.