This is the S4ACS release v1.55.0. In the following sections, the major and minor changes included in this version are brifely presented.

Major changes

• The class responbile for creating the log files were refactored. Now, by setting a front panel parameter, S4ACS allows to choose between the log levels STATUS, DEBBUG, INFO, WARNING, ERROR, and CRITICAL. When chosing the INFO log level, for example, S4ACS will write in the log file all the messages with the level INFO or above.
• The read noise and gain values related to the EMCCD camera 14364 were included in the csv files used by the Python script to create the image headers.

Minor changes

• Some non-used parameters related to the S4ACS initialization were removed. Besides, the configuration of the parameters is disabled after the execution of the software.
• Log messages with the level of DEBBUG and STATUS were added to the code.
• The waveplate status verification algorithm done by S4ACS before the start of an exposure was refactored using the LabVIEW library to deal with JSON strings.
• The template S4ACS configuration file was modified to include the log level parameter.
• Now, a runtime error stops the S4ACS execution.
• Some classes that were not being used were removed from the project.