diff --git a/noctua/config/constants.py b/noctua/config/constants.py
index 191aa7e5e3f0702625a823bb3941790e07c7a863..3829f6707447f2afacaca9bef6a82d6e15022ce0 100644
--- a/noctua/config/constants.py
+++ b/noctua/config/constants.py
@@ -1,6 +1,10 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
+'''
+Constants used in the whole project
+'''
+
 # Telescope
 
 lat = 44.5912  # [°] Latitude North from Greenwich.
@@ -109,10 +113,13 @@ image_number = {v: k for k, v in image_state.items()}
 # Directories
 ############
 
-data_folder = "data"
+DATA_FOLDER_NAME = "data"
+LOG_DIRECTORY_NAME = "log"
 fits_folder = "fits"
 focus_folder = "focus"
-log_folder = "log"
+
+# data_folder = "data"
+# log_folder = "log"
 
 dir_type = {
     0: "dark",
@@ -124,6 +131,21 @@ dir_type = {
 # Reversing dir_type
 dir_number = {v: k for k, v in dir_type.items()}
 
+############
+# Logging
+############
+
+# Log file naming
+LOG_FILE_EXTENSION = ".log"
+LATEST_LOG_FILENAME = "latest"
+
+# Rotation settings (used by logger.py)
+LOG_ROTATION_TIME_H = 12 # Midday (hour in UTC)
+LOG_ROTATION_TIME_M = 0  # Midday (minute in UTC)
+LOG_ROTATION_TIME_S = 0  # Midday (second in UTC)
+LOG_ROTATION_INTERVAL_DAYS = 1 # Rotate daily
+LOG_BACKUP_COUNT = 0 # 0 means keep all backup files (infinite)
+
 ############
 # FITS
 ############
@@ -132,10 +154,6 @@ dir_number = {v: k for k, v in dir_type.items()}
 imagetyp = "IMAGETYP"  # 'Light'
 dateobs = "DATE-OBS"  # '2021-12-18T05:09:56.163'
 
-# File prefix
-prefix = "OARPAF."
-
-# File extension
-ext = ".fits"
-log_ext = ".log"
+FILE_PREFIX = "OARPAF."
+ext = ".fits" # File extension
 focus_ext = ".foc"
diff --git a/noctua/sequencer.py b/noctua/sequencer.py
index fad5c14b0499786e0ebeaa7989ac18fa87f2cf69..57df98815caf4b3b97eb61bbfb1802bdbc7d5356 100755
--- a/noctua/sequencer.py
+++ b/noctua/sequencer.py
@@ -8,6 +8,7 @@ Sequencer module for Observation Blocks (OBs) in JSON format
 # System modules
 import argparse
 import importlib
+import importlib.resources
 import json
 import os
 import signal
@@ -396,7 +397,5 @@ def cli():
 
 
 if __name__ == "__main__":
-    '''
-    If called alone
-    '''
+    # If called alone
     cli()
diff --git a/noctua/utils/analysis.py b/noctua/utils/analysis.py
index 15edf408d36b5cbc033faa088f4eb0c78a09c40e..9bbaa8b6ef5ad875b5ec4e532e57600596bc84a8 100644
--- a/noctua/utils/analysis.py
+++ b/noctua/utils/analysis.py
@@ -152,14 +152,11 @@ def fit_star(
 
         gp.plotimage(
 
-            (data, dict(
-                xlabel="data")),
+            (data, {"xlabel": "data"}),
 
-            (fitted_model(x, y), dict(
-                xlabel="model")),
+            (fitted_model(x, y), {"xlabel": "model"}),
 
-            (residuals, dict(
-                xlabel="Residuals")),
+            (residuals, {"xlabel": "Residuals"}),
 
             unset="grid",
             set="size square",
diff --git a/noctua/utils/logger.py b/noctua/utils/logger.py
index a45c31e8790cab155610abd2873b807a44e121ff..d6e884563e6c1c79ca7dbb497d2dd456394a2640 100644
--- a/noctua/utils/logger.py
+++ b/noctua/utils/logger.py
@@ -1,55 +1,231 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
 
 """Custom format log"""
 
 # System modules
+import logging
+import logging.handlers
 import sys
+from pathlib import Path
+from datetime import datetime, time
 
 # Third-party modules
-from loguru import logger
-
-# Other templates
-from .structure import log_path
-
-
-def mylog():
-    "logger function"
-
-    logger.remove()
-
-    time = "{time:YYYY-MM-DD HH:mm:ss.SSSSSS!UTC} "
-    level = "<level>{level: <8}</level> "
-    message = "| {message} "
-    stack = "<bold>({module}.{function}:{line})</bold>"
-    fmt = time + level + message + stack
-
-    # On standard output
-    logger.add(sys.stderr, format=fmt)
-
-    # On file
-    log_day = log_path("{time:YYYY-MM-DD!UTC}")
-    logger.add(log_day, format=fmt, colorize=True, rotation="1 day")
-
-    # Custom levels
-    logger.level("DEBUG", color="<magenta><bold>")
-    logger.level("INFO", color="<green><bold>")
-
-    return logger
-
-
-def main():
-    """Main function"""
-
-    log = mylog()
-
-    log.debug("debug message")
-    log.info("info message")
-    log.warning("warning message")
-    log.error("error message")
-    log.critical("critical message")
 
+# Custom modules
+from ..config.constants import (
+    LOG_DIRECTORY_NAME, DATA_FOLDER_NAME,
+    FILE_PREFIX, LOG_FILE_EXTENSION, LATEST_LOG_FILENAME,
+    LOG_ROTATION_TIME_H, LOG_ROTATION_TIME_M, LOG_ROTATION_TIME_S,
+    LOG_ROTATION_INTERVAL_DAYS, LOG_BACKUP_COUNT
+)
+from .structure import get_log_dir_path, get_dated_log_filepath, get_latest_log_filepath
+
+LOG_DIR = get_log_dir_path() # Creates directory if it doesn't exist
+LATEST_LOG_FILEPATH = get_latest_log_filepath()
+
+log = None # Global logger instance
+
+class ColorizingFormatter(logging.Formatter):
+    """
+    A custom logging formatter that adds ANSI color codes to log level names
+    for console output.
+    """
+
+    # Color codes
+    BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)
+
+    # Log level to color mapping Using bold for emphasis
+    LEVEL_COLORS = {
+        logging.DEBUG: f"\x1b[3{MAGENTA};1m",  # Bold Magenta
+        logging.INFO: f"\x1b[3{GREEN};1m",    # Bold Green
+        logging.WARNING: f"\x1b[3{YELLOW};1m", # Bold Yellow
+        logging.ERROR: f"\x1b[3{RED};1m",      # Bold Red
+        logging.CRITICAL: f"\x1b[4{RED};1m",   # Bold Red with Red Background (or just very bold red)
+                                               # Let's use bold bright red: f"\x1b[31;1;91m"
+                                               # Or just very bold red: f"\x1b[31;1m" - let's stick to simpler bold red for CRITICAL
+    }
+    RESET_SEQ = "\x1b[0m" # Reset all attributes
+
+    def __init__(self, fmt=None, datefmt=None, style='%', validate=True, *, defaults=None):
+        super().__init__(fmt, datefmt, style, validate, defaults=defaults)
+        # For UTC timestamps if needed by the base Formatter
+        self.converter = lambda *args: datetime.utcnow().timetuple()
+
+
+    def format(self, record):
+        s = super().format(record)
+
+        levelname_str = record.levelname
+        color = self.LEVEL_COLORS.get(record.levelno)
+
+        if color:
+            padded_levelname = f"{record.levelname:<8}" # Adjust padding if different
+
+            if padded_levelname in s:
+                colored_levelname = f"{color}{padded_levelname}{self.RESET_SEQ}"
+                s = s.replace(padded_levelname, colored_levelname, 1) # Replace only the first occurrence
+            else: # Fallback if padded version not found, try raw (less likely to match in typical formats)
+                if record.levelname in s:
+                    colored_levelname = f"{color}{record.levelname}{self.RESET_SEQ}"
+                    s = s.replace(record.levelname, colored_levelname, 1)
+        return s
+
+
+def setup_logger(name="noctua_logger", log_level=logging.DEBUG):
+    global log
+    if log:
+        return log
+
+    logger_instance = logging.getLogger(name)
+    logger_instance.setLevel(log_level)
+
+    if logger_instance.hasHandlers():
+        logger_instance.handlers.clear()
+
+    log_format_str = "%(asctime)s.%(msecs)03d | %(levelname)-8s | %(message)s (%(module)s.%(funcName)s:%(lineno)d)"
+    formatter = logging.Formatter(log_format_str, datefmt="%Y-%m-%d %H:%M:%S")
+    # Ensure timestamps are in UTC
+    formatter.converter = lambda *args: datetime.utcnow().timetuple()
+
+    console_handler = logging.StreamHandler(sys.stderr)
+    formatter = ColorizingFormatter(log_format_str, datefmt="%Y-%m-%d %H:%M:%S")
+    console_handler.setFormatter(formatter)
+    logger_instance.addHandler(console_handler)
+
+    # --- TimedRotatingFileHandler for LATEST log ---
+    # Rotate at midday UTC
+    rotation_time_utc = time(
+        hour=LOG_ROTATION_TIME_H,
+        minute=LOG_ROTATION_TIME_M,
+        second=LOG_ROTATION_TIME_S,
+        tzinfo=None # Naive time, assumed UTC by the handler when utc=True
+    )
+
+    rotating_file_handler = logging.handlers.TimedRotatingFileHandler(
+        filename=LATEST_LOG_FILEPATH,
+        when="midnight", # Base rotation type (daily)
+        atTime=rotation_time_utc, # Specific time for rotation
+        interval=LOG_ROTATION_INTERVAL_DAYS, # Interval (1 for daily)
+        backupCount=LOG_BACKUP_COUNT, # 0 means keep all backups
+        encoding='utf-8',
+        utc=True # IMPORTANT: Use UTC for rotation calculations and atTime
+    )
+
+    def custom_namer_astronomical(default_name):
+        # default_name will be like /path/to/OARPAF.latest.log.YYYY-MM-DD_HH-MM-SS (if atTime is used)
+        # or /path/to/OARPAF.latest.log.YYYY-MM-DD (if when='midnight' and no atTime)
+        # We want /path/to/OARPAF.ASTRO_DATE.log where ASTRO_DATE changes at midday.
+
+        # The date embedded by TimedRotatingFileHandler in default_name is the *calendar date*
+        # of the *end* of the logging period (i.e., when rotation occurs).
+        # For midday rotation, if rotation happens on 2023-04-16 at 12:00 UTC,
+        # the log being rotated contains messages from 2023-04-15 12:00 UTC to 2023-04-16 11:59 UTC.
+        # So, the log *pertains* to the astronomical night of 2023-04-15.
+
+        # Extract the calendar date suffix added by the handler
+        try:
+            # Example: '/.../OARPAF.latest.log.2023-04-16' (if rotated at midnight)
+            # Example: '/.../OARPAF.latest.log.2023-04-16_12-00-00' (if rotated with atTime)
+            base_filepath = Path(default_name)
+            suffix = base_filepath.suffix # .log or .2023-04-16 or .2023-04-16_12-00-00 (depends on exact TimedRotatingFileHandler version and usage)
+            
+            # A more robust way to get the date part that TimedRotatingFileHandler uses for rotation:
+            # The date used for the suffix is based on the rolloverAt time.
+            # We need to determine the "astronomical date" this log corresponds to.
+            # `self.rolloverAt` is when the next rollover will happen.
+            # The file being closed contains logs *before* `self.rolloverAt`.
+            # So, the timestamp of the logs is generally `self.rolloverAt - interval`.
+            # Let's assume the default_name already contains the calendar date of rotation.
+            
+            # Try to parse the date from the default_name
+            # This is a bit fragile as it depends on TimedRotatingFileHandler's naming convention
+            date_str_part = base_filepath.name.replace(LATEST_LOG_FILEPATH.name + '.', '') # Removes base filename and first dot
+            date_str_part = date_str_part.split('_')[0] # Takes YYYY-MM-DD part if HH-MM-SS is appended
+            
+            rotation_calendar_date = datetime.strptime(date_str_part, "%Y-%m-%d").date()
+
+            # This rotation_calendar_date is when the rotation *occurred*.
+            # If rotation is at midday (e.g., 2023-04-16 12:00 UTC),
+            # the log file being closed contains data for the astronomical night
+            # that *ended* on this date. So, the astronomical date is one day prior.
+            astronomical_date_of_log = rotation_calendar_date - timedelta(days=1)
+            astro_date_str = astronomical_date_of_log.strftime("%Y-%m-%d")
+            
+            # Use structure.py to build the final path for consistency
+            return str(get_dated_log_filepath(astro_date_str))
+            
+        except ValueError:
+            # Fallback if date parsing fails
+            log.warning(f"Could not parse date from default rotated log name: {default_name}. Using default.")
+            return default_name
+
+    # For `atTime` to work as expected and `custom_namer_astronomical` to get the correct date,
+    # it's simpler to handle the astronomical date logic more directly if possible.
+    # The `TimedRotatingFileHandler` is primarily designed around calendar days.
+    # A common workaround for astronomical logging is to rotate daily at UTC 00:00 or 12:00
+    # and then have a *separate script* or process that renames the rotated log files
+    # according to the astronomical date convention if the handler's naming isn't perfect.
+
+    # Given the complexity of precisely aligning TimedRotatingFileHandler's internal date logic
+    # with astronomical "day" changes via just `namer`, let's use a simpler `namer`
+    # that just cleans up the default TimedRotatingFileHandler name format.
+    # The astronomical date logic is better handled in how you *interpret* or search for logs.
+
+    def simpler_custom_namer(default_name):
+        # default_name for TimedRotatingFileHandler with atTime and utc=True
+        # is typically `basename.YYYY-MM-DD_HH-MM-SS` where YYYY-MM-DD_HH-MM-SS is the UTC time of rotation.
+        # Or `basename.YYYY-MM-DD` if `when` is 'midnight' and `atTime` is not used, or if `atTime` is midnight.
+        # We want `LOG_FILE_PREFIX + YYYY-MM-DD + LOG_FILE_EXTENSION`
+        # The date in the filename should represent the *start* of the observing night.
+        
+        base_filepath = Path(default_name)
+        # Example default_name: /path/to/OARPAF.latest.log.2023-04-15_12-00-00
+        # The date/time in the suffix is when the rotation *occurred*.
+        # The logs *before* this time are in this rotated file.
+        
+        # Extract the date part from the suffix
+        # Suffix might be ".YYYY-MM-DD" or ".YYYY-MM-DD_HH-MM-SS"
+        name_parts = base_filepath.name.split(LATEST_LOG_FILEPATH.name + '.')
+        if len(name_parts) > 1:
+            timestamp_suffix = name_parts[1]
+            date_str = timestamp_suffix.split('_')[0] # Get the YYYY-MM-DD part
+            
+            # This date_str is the calendar date when the file was *closed* (rotation happened).
+            # For midday rotation (e.g., 12:00 UTC on YYYY-MM-DD), the logs in this file
+            # pertain to the astronomical night of YYYY-MM-(DD-1).
+            try:
+                rotation_event_date = datetime.strptime(date_str, "%Y-%m-%d").date()
+                # The log contains data for the astronomical night *before* this rotation event date.
+                log_file_astro_date = rotation_event_date - timedelta(days=1)
+                final_date_str = log_file_astro_date.strftime("%Y-%m-%d")
+                
+                # Construct the desired filename using structure.py for consistency
+                return str(get_dated_log_filepath(final_date_str))
+            except ValueError:
+                pass # Fall through to default if parsing fails
+
+        # Fallback to a cleaned-up version of the default name if parsing is tricky
+        dir_name = base_filepath.parent
+        original_plus_date = base_filepath.name.replace(LOG_FILE_EXTENSION, '') # Remove .log
+        # original_plus_date is like OARPAF.latest.YYYY-MM-DD or OARPAF.latest.YYYY-MM-DD_HH-MM-SS
+        cleaned_name = original_plus_date.replace(LATEST_LOG_FILENAME + '.', '') # Becomes OARPAF.YYYY-MM-DD...
+        return str(dir_name / (cleaned_name + LOG_FILE_EXTENSION))
+
+    rotating_file_handler.namer = simpler_custom_namer # Use the simpler namer
+    rotating_file_handler.setFormatter(formatter)
+    logger_instance.addHandler(rotating_file_handler)
+    
+    log = logger_instance
+    log.info(f"Logger '{name}' configured. Current logs to: {LATEST_LOG_FILEPATH}")
+    log.info(f"Rotated daily at {rotation_time_utc} UTC. Backup count: {'Infinite' if LOG_BACKUP_COUNT == 0 else LOG_BACKUP_COUNT}.")
+    return log
+
+# Initialize logger on module import
+from datetime import timedelta # Ensure timedelta is imported for namer
+log = setup_logger()
 
 if __name__ == "__main__":
-    main()
-else:
-    log = mylog()
+    log.debug("This is a debug message from logger.py main.")
+    log.info("This is an info message.")
+    # ... rest of your test code ...
diff --git a/noctua/utils/structure.py b/noctua/utils/structure.py
index 69f445933809d6045479d5e4bea6de0e0935d3c0..3e0e260127c06ca7a5c1ec2adf4d31fabf2ae870 100644
--- a/noctua/utils/structure.py
+++ b/noctua/utils/structure.py
@@ -13,49 +13,44 @@ from pathlib import Path
 from astropy.io import fits
 from astropy.time import Time
 
-# Other templates
-# from utils.logger import log
-from ..config.constants import (data_folder, dateobs, dir_type, ext,
-                                fits_folder, focus_ext, focus_folder,
-                                frame_number, imagetyp, log_ext, log_folder,
-                                prefix)
+# Custom modules
+from ..config.constants import (
+    DATA_FOLDER_NAME, LOG_DIRECTORY_NAME,
+    FILE_PREFIX, LOG_FILE_EXTENSION, LATEST_LOG_FILENAME,
+    dateobs, dir_type, ext, fits_folder,
+    frame_number, imagetyp, focus_folder, focus_ext
+)
+
+PROJECT_ROOT = Path(__file__).parent.parent.parent
 
 
 def date_folder():
+    """Create a date folder string based on astronomical convention
+    (changes at midday UTC).
     """
-    Create a date folder
-    """
-
-    now = Time.now()  # 2021-12-28T10:00:00.123456
-    if now.datetime.hour < 12:  # from midnight to midday...
-        folder_date = now - 1  # ...subtract one day
+    now = Time.now()
+    # If current UTC hour is before midday UTC, the "observing night"
+    # belongs to the previous calendar date.
+    if now.datetime.hour < 12: 
+        folder_date_obj = now.datetime.date() - timedelta(days=1)
     else:
-        folder_date = now
-
-    # 2021-12-27
-    folder_name = str(folder_date).split()[0]
-
-    return folder_name
+        folder_date_obj = now.datetime.date()
+    return folder_date_obj.strftime("%Y-%m-%d")
 
 
 def frame_folder(header):
     """
     Create a folder depending on the image type in FITS header
     """
-
     frame = header[imagetyp]
-    # Takes
-    # frame_type or frame_number
-
     if isinstance(frame, int):
-        # 1 -> object/
         folder_name = dir_type[frame]
-    else:  # str
-        # 'Light Frame' -> Light -> [1] -> 1
-        frame = [v for k, v in frame_number.items() if k in frame][0]
-        # 1 -> object/
-        folder_name = dir_type[frame]
-
+    else:
+        frame_num_list = [v for k, v in frame_number.items() if k in frame]
+        if not frame_num_list:
+            # Fallback if frame type string is not recognized
+            return "unknown_type"
+        folder_name = dir_type[frame_num_list[0]]
     return folder_name
 
 
@@ -63,89 +58,84 @@ def fits_path(header, dry=False):
     """
     Create a fits file path where the file will be stored
     """
+    
+    root = PROJECT_ROOT / DATA_FOLDER_NAME / fits_folder
 
-    # data/fits/
-    root = Path(data_folder, fits_folder)
-
-    # 2021-12-27
-    date = date_folder()
-    date = Path(date)
+    date_str = date_folder() 
+    date_path_part = Path(date_str)
 
-    # 'Light Frame' -> Light -> object/
-    frame = frame_folder(header)
-    frame = Path(frame)
-
-    # data/fits/2021-12-27/object/OARPAF.blabla.fits
-    path = [root, date, frame]
-    path = Path.joinpath(*path)
+    frame_path_part = Path(frame_folder(header))
+    path = root / date_path_part / frame_path_part
 
     if not dry:
         path.mkdir(parents=True, exist_ok=True)
-
     return path
 
 
-def log_path(timestamp, dry=False):
+def get_log_dir_path(dry=False):
     """
-    Create the log file name and its path
+    Returns the Path object for the log directory.
+    Creates it if it doesn't exist (unless dry=True).
     """
-
-    # data/log/
-    root = Path(data_folder, log_folder)
-    path = root
-
+    log_dir = PROJECT_ROOT / DATA_FOLDER_NAME / LOG_DIRECTORY_NAME
     if not dry:
-        path.mkdir(parents=True, exist_ok=True)
+        log_dir.mkdir(parents=True, exist_ok=True)
+    return log_dir
 
-    # OARPAF.2021-12-27.log
-    outfile = prefix + timestamp + log_ext
-
-    # data/log/OARPAF.2021-12-27.log
-    outpath = Path.joinpath(path, outfile)
+def get_dated_log_filepath(date_str, dry=False):
+    """
+    Constructs a path for an expected date-stamped (rotated) log
+    file.  date_str: A string like "YYYY-MM-DD"
+    """
+    
+    log_dir = get_log_dir_path(dry=dry)
+    # Filename: OARPAF.YYYY-MM-DD.log
+    log_filename = f"{FILE_PREFIX}{date_str}{LOG_FILE_EXTENSION}"
+    return log_dir / log_filename
 
-    return outpath
+def get_latest_log_filepath(dry=False):
+    """
+    Constructs the path for the "latest" log file.
+    """
+    log_dir = get_log_dir_path(dry=dry)
+    latest_filename = f"{FILE_PREFIX}{LATEST_LOG_FILENAME}{LOG_FILE_EXTENSION}"
+    return log_dir / latest_filename
 
 
 def foc_path(timestamp, dry=False):
     """
     Create the focus output text file name and its path
     """
-
-    # data/focus/
-    root = Path(data_folder, focus_folder)
+    
+    root = PROJECT_ROOT / DATA_FOLDER_NAME / focus_folder
     path = root
 
     if not dry:
         path.mkdir(parents=True, exist_ok=True)
 
-    # OARPAF.2021-12-27.foc
-    outfile = prefix + timestamp + focus_ext
-
-    # data/focus/OARPAF.2021-12-27.foc
-    outpath = Path.joinpath(path, outfile)
-
+    # OARPAF.YYYY-MM-DD.foc
+    outfile = f"{FILE_PREFIX}{timestamp}{focus_ext}"
+    outpath = path / outfile
     return outpath
 
 
-def save_filename(infile):
+def save_filename(infile_path_str):
     """
     Save a fits file in its path with an ESO-style filename.
     """
-
-    inpath = Path(infile)
-
-    header = fits.getheader(infile)
+    
+    inpath = Path(infile_path_str)
+    header = fits.getheader(inpath)
 
     # '2021-12-28T20:09:56.163'
-    name = Time(header[dateobs]).isot
-    # "OARPAF." + name + ".fits"
-    outfile = Path(prefix + name + ext)
-
-    # data/fits/2021-12-27/object/OARPAF.blabla.fits
-    outdir = fits_path(header)
+    date_obs_str = header[dateobs] # DATE-OBS from FITS header
+    name_for_file = Time(date_obs_str).isot
+    
+    outfile_name = f"{FILE_PREFIX}{name_for_file}{ext}"
+    outfile = Path(outfile_name)
 
-    outpath = Path.joinpath(outdir, outfile)
+    outdir = fits_path(header) # This already creates the directory
+    outpath = outdir / outfile
 
-    shutil.copy2(inpath, outpath)  # For Python 3.8+.
-
-    return outpath
+    shutil.copy2(inpath, outpath)
+    return str(outpath) 
diff --git a/pyproject.toml b/pyproject.toml
index ef6b73891a6e35e85ca0c5de55cd3a361853d878..445eb777b7f851e50d0f857cd9deaddab6fb1c54 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -26,7 +26,6 @@ classifiers = [
 
 dependencies = [
     "requests",
-    "loguru",
     "astropy",
     "gnuplotlib", ## If focus.py
     "pyvantagepro", # If meteo.py