1. ASTRON VERSION 2.0 HOME PAGE

2. There are other settings too. All settable items are in blue.
CHOOSE SETTINGS
A: Choose GMT or Ship’s Time
B: Choose Time Zones or Zone Differences
C: Choose SHA or Right Ascension
D: Choose Feet or Metres
E: Choose Fahrenheit or Celsius
F: Choose Hectopascals or Inches of Mercury
There are other settings too. All settable items are in blue. s

3. HOME PAGE - ALMANAC SECTION
Insert all 9 date/time values on top line.
Choose body. (Sun, Moon, 5 planets, 58 stars.)
Data entry cells are this colour.
Result cells, GHA and Dec, are in this colour.
Additional information cells are on light green background.
Semi Diameter, Horizontal Parallax , Rise, Set and Mer Passage times are listed further down the page (not shown here)
The “Equation of Time” cell is only for the Sun.
For the Moon, it changes to Phase.
For other bodies, it changes to Magnitude.

4. HOME PAGE - APPARENT POSITION SECTION
Now enter Assumed Latitude and Longitude.
Astron calculates the true Azimuth and Altitude
for the entered position and time.

5. HOME PAGE - SEXTANT ALTITUDE CORRECTIONS SECTION
Enter values into the 7 input cells.
Astron corrects your measured sextant altitude (Hs) for
Index, Dip, Refraction, Semi Diameter and Parallax to give
the Observed Altitude (Ho) result.
This will differ from the Computed Altitude (Hc) unless your
observation was perfect and your Assumed Position was exact.

6. HOME PAGE - AZIMUTH and INTERCEPT result
The Azimuth and Intercept result is the difference between
Calculated Altitude and Observed Altitude.
You can now plot this as a conventional Line of Position (LoP).
Alternatively, you can press the “Add Sight” button to add this
to the Sight Log and Sight Plotter which we will explain later.
Please note that this presentation is just an outline. For a full
explanation of any feature of Astron, refer to the User Notes.

7. HOME PAGE - Other information displayed
Display of both GMT and Ship’s Time. The selected time input mode is in green.
Dawn and dusk observation windows.
These are always in Ship’s time.
Unidentified Body utility. Enter the approximate
Bearing and altitude. Astron shows the nearest
Body to this position. Also the arc distance between
such body and the selected body.
The arc distance between the Moon and the selected body
Mer Passage Pop-Up. Indicates that this sight may be suitable for Meridian Passage analysis.
(Similar pop-up if suitable for a Lunar Sight.)
Rise, Meridian Passage and Set times for the selected body. (For entered limb, eye height, etc.)
Tabs to select other facilities on other pages.

8. SIGHT LOG and SIGHT PLOTTER
See next 2 slides for more detail

9. SIGHT LOG and SIGHT PLOTTER
Two sights have been added here. Here the ‘fix time’ is the time of the later sight.
The vessel is moving 053 degrees at 6.4 knots.
Note the Assumed Position of the earlier sight has been advanced 1.6nm.
The next slide shows the plot of this. Feel free to switch between the two slides.
You could have set the fix time to (say) 19:00:00, in which case all sights
would be advanced accordingly.

10. The colours of the LoP’s are the same as in the sight log above.
Note the ‘origin’ of the first sight has been advanced 053/1.6.
The green bar at the top gives chart information. (Mouse cursor did
not copy in this screenshot. It was at the LoP intersection.)
Chart scale and centre can easily be adjusted.
See User Notes for how to do this.

11. This slide is for the location and time of the previous sight plotter example.

12. Too much to explain here! Please read User Notes Chapter 18.
Lunar Sight page. Screenshot of the example in User Notes Chapter 18.
Too much to explain here! Please read User Notes Chapter 18.

13. Please read User Notes Chapter 11.
Meridian Passage Page.
Screenshot of the example in User Notes Appendix on Oct 15th , 2024.
This is an extreme example when the Moon’s declination change rate is over 18’ per hour.
If uncorrected, an error of 5m 55s and 1° 25.7’ longitude would occur.
Could be greater on a moving vessel!
Please read User Notes Chapter 11.

14. Please read User Notes for full details of Astron.
Thank you for viewing this outline presentation.
The author hopes you enjoy using Astron.
Please read User Notes for full details of Astron.