Use *declination auto instead of individual *calibrate compass statements

[goatchurchprime]

From: https://survex.com/docs/manual/datafile.htm

If you have specified the output coordinate system (using *cs out) then you can use *declination auto (and we recommend that you do). This is supported since Survex 1.2.21 and automatically calculates magnetic declinations based on the IGRF (International Geomagnetic Reference Field) model for the specified date of each survey and at the specified representative location (given in the current input coordinate system, as set with *cs). Survex 1.2.27 and later also automatically correct for grid convergence (the difference between Grid North and True North) when *declination auto is in use, based on the same specified representative location.

[jarvist]

Certainly there is an argument for this now that Survex supports it, but doing so would turn our treatment of declination into an entirely black box, and introduce differences with the published surveys.

I quite like the fact that we understand + control for the declination at the same time as the expeditions' trance of data. (i.e. no one can typo the year on data entry + throw their survey out of whack. Even if this was eventually debugged, it would probably be missed in-the-field.)

https://github.com/jarvist/migovecsurveydata/blob/master/migovecsurveydata/declination.dat

[goatchurchprime]

Cave surveys are always changing shape each year (compared to what was published the previous year) as connections get added, if you use something like: https://github.com/CaveSurveying/tunnelx It's not something to be afraid of.