From Evan's email to the DARN-users mailing list of Aug. 27, 2018:

New features in version 4.2 of the RST include:

- TS18 and TS18-Kp statistical convection model (TS18 replacing CS10 as default)
- Statistical convection model solver (solve_model)
- Added pre-1900 coefficients for use with AACGM_v2
- Implemented new --version option to print current RST version number
- Added unrecognized command line option handling to remaining binaries
- Disabled low-power thresholding when converting between dat and rawacf format files
- Fixed bug when reading data from early (~1993-1995) dat format files
- Fixed bug when reading records with negative scan flag values
- Fixed bugs in gridtogrdmap and maptocnvmap conversion routines
- Fixed bug in trim_fit to allow removal of first record in file
- Fixed bug in map_addhmb when specifying custom boundary latitude
- Fixed bug in make_grid preventing custom start times with -i flag
- Fixed bugs in AACGM_v2 software
- Fixed numerous plotting bugs
- Updated Falkland Islands and Stokkseyri hdw.dat files
- Updated README and documentation for FITACF 3.0
- Updated documentation following the -new/-old flag change from previous release (4.1)
- Cleanup of numerous warning messages during compilation

zip and tar.gz archives of RST 4.2 may be downloaded directly using the links below:

https://github.com/SuperDARN/rst/archive/v4.2.zip(external link)
https://github.com/SuperDARN/rst/archive/v4.2.tar.gz(external link)

A citable DOI is again available for this version of the software (https://doi.org/10.5281/zenodo.1403226) and updated documentation is available at the link below:

https://superdarn.github.io/rst/(external link)

Many thanks to those who contributed to this new release: P. V. Ponomarenko (our WG chair), D. D. Billett, E. C. Bland, A. G. Burrell, K. Kotyk, A. S. Reimer, M. Schmidt, S. G. Shepherd, K. T. Sterne, and M.-T. Walach