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Welcome to the AstroNavi wiki! Special Thanks to P.Lutus and his "eph". This software uses some ideas of P.Lutus but in my opinion it's very different.
Images may not represent the current layout. Layout will change if required. Version 20230219
Changelog:
- 20230303 Masses of changes made to Astronavigator. GUI changed, calculation support now 3 modes, a lot of more or less simple bugs also fixed
- 20230220 Added two buttons to allow increment/decrement of charset size
This is just a simple app. Three input masks.
| Abbreviatons | ||
|---|---|---|
| NA | (Nautical Almanac or Long Term Almanac) | |
| DMS | (Degree Minutes Seconds format as used by sailors and in the NA) | |
| CB | (Celestial Body) | |
| Ho | (Height observed with Sextant) | |
| Hc | (Height calculated by using corrections from NA) | |
| DR | (Dead Reconning. German: Koppelposition) | |
| SRF | (Sight Reduction Form) |
First: Simple Navigation (SUN)
Three input fields. Two DMS format one HMS format. There is no real plausibility check.
Allowed DMS format is 0°0'0" to 000°00.0'00.00"
Allowed HMS format is 00:00:00 (24h format)
The reason why I allow 00.0' (minutes) is just given by the NA. We read a sextant with xxx°yy'ss.ss" but in the NA we find figures like xxx°yy.y' but no seconds instead fractions of minutes. That's why I allow such stupid format which makes it hard to parse. Design of proper GUI takes much more effort than calculation of position.
Input field Hc-computed can be at least your sextant reading of a given CB or a corrected version. If you click on HO Button you get a much more complex mask to add a proper Sextant measurement (Headline: Sextant Correction).
Second: "Sextant Correction"
In the "Sextant Correction" Dialog you can add your Sextant measurment and add the corrections as given by Nautical Almanac. The Index Error is a figure related to your Sextant. You should know this figure and how to get it.
DIP is the altitude above sea level. You should know your altitude and get the DIP figure from NA. Atmospheric corrections matter if the CB was nearby horizon. You can add LIMB taken from NA as additional corrections.
The current version of this software calculates the DIP by entering the height above sealevel in meters. A user can enter the DIP from the NA if available instead of using the internal calculation,
The dialog also offers to calculate the refraction by entering temparature and airpressure while measuring the CB. It#s also possible to enter refraction from NA instead.
The mask will check input. If "Hc DMS", "Hc Decimal" and "Sextant Altitide SA" show green you can leave the mask by using back. The reset button will reset all of the fields but not Ho.
Minus sign: -000°00'00" and E,e,O,o,S,s instead of - are treated same. E000°00'00" is just same as first DMS in this row.
The button "GET A FIX" in the "Simple Navigation" dialog will open a much more complex dialog.
Third: "Nautical Almanac"
It requires all of the input as required by the NA calculations form. To check this mask after first install and add some proper values to the field first press "EXAMPLE NA".
Than the data for three stars are loaded to the mask. After that you can check the math by pressing "CALC". The NA requires to iteration steps to get a proper position from your DR position. That's why first calculation gives as Status "Precision poor" plus red background. Press Calc a second time that you will get a second iteration calculation (That's exactly the way it works in NA) and a green background with "Precision good".
To add data for three stars my choice was to manage this with three radio buttons. A tabbed dialog takes too much space at the screen. "CB#1 to CB#3" select one of three CB. You can only select the CB as offered by "PREV" and "NEXT" button. Others are not allowed. Because of a feature whoch calculates the position without a NA. All of the astro data are just inside the software. To use this mode press the check box "By NA or Calculated". Howver, this mode is up to now not implemented.
You can add for each CB sighting by pressing "HO2HC" the "Sextant Correction" as described above. This data are only related to "CB#2, CB#2 and CB#3" but not to a real star. Remember this. It just calculates the figure for Hc and push it to the "Hc-omput" field of the given CB in the "Nautical Almanac" dialog, if called from this dialog. It do nothing else.
There is one well known "Bug" in this software. Sometimes, after installation" the "Back" button in the "Sextant Correction" will not open the callers window. Don't know what's wrong there. It works after initialized fist time correct as well. Maybe the reason is a false default after installation.
Fourth: "Celestial Body Correction"
The software also offers a dialog to modify the data of Celestial Bodys used in this software (up to now, 20230303 not for SUN, MOON and PLANETS) to get proper precalculations of SHA and DECLINATION to become "independent" from an ALMANAC. However, that's bad practice. Buy and use an ALMANAC. This software reduce the time to calculate a position from up to 5 hours to a few seconds but it offers methods and know how to do it completely by yourself!
The way this dialog works:
- Find CB by using NEXT and PREV button.
- Change SHA, SHAcorrection, DECLINATION and DECLINATIONcorrection plus Date and Time and compare SHA Today, DECLINATION Today with the figures for given time in the ALMANAC. Change the correction values or start values (DHA/DECLINATION) until the results for different month are good. Data is stored to the cellphones Shared Preferences memory. If you want to reset data to the implemented defaults than just press RESET button for the shown CB. This do not work up to now (20230303) for SUN, CB, PLANETS.