NightMon - Allsky night monitor

Software package for NightMon v1

Creative Commons Attribution-ShareAlike 4.0 International License


The aim of this project is to develop a system capable of remotely controlling a night light monitoring allsky multiple cameras system with a raspberry pi 4b (RPI). As for the version 1, we use two cameras, one with Johnson V filter and the second with the Johnson R filter. This system is designed in the perspective of replacing the well known AstMon system.

The linux distribution used for this system is Raspberry Pi OS (32-bit). We chose a development philosophy based on a complete control from the Linux command line. The system can be controlled simply with a low speed remote connection provided by a SSH client installed on the user workstation. The RPI connected to the system act as a server. Also to promote the implementation of measuring network, the data acquired by the NightMon is stored on a web server installed on the RPI. Thanks to that web server, the data from multiple NightMon units all around the world can be downloaded by a central server. Locally, the web server can be accessed with any portable device through a proprietary wifi network. SSH can also be accessed through this wifi network.

How to access the NightMon

From internet:

ssh -p 2022 sand@router_public_ip


inside a private network

ssh sand@servers_local_ip

From the internet, port 2022 is used instead of standard port 22 to reduce risk of attacks by hackers. A password and user name is required. The standard username is sand. The system administrator should be able to provide you the password for sand.

Hardware requirements

We highly suggest to chose hardware components better or equivalent of this:

  • rapsberry pi 4b+ with 4 Gb of RAM
  • 128 Gb microsd card U30
  • 512 Gb usb stick


There are 53 MB of data stored on the microsd card every cycle of 15min. Which means 2.5 GB per day in average. The raw images and the jpeg images occupy the most of that space (more than 99%). The 128 GB card can then store about 50 days. The complete data will be kept untouched the last two weeks while raw and jpeg images between 2 weeks and 4 weeks will be compressed with gunzip. Older images will be erased from the microsd card.

Files are copied on the backup USB stick. The USB stick being four times larger, we will keep 8 weeks of full data, data betwen 8 to 16 weeks old will be compressed and after that the raw and jpeg images will be erased from the USB stick. If you need to keep the raw data for a longer period, then it is mandatory to backup them elsewhere.

Installing and configuring subsystems

Basic system installations and dependencies

  • Download and install the Raspberry Pi Imager ( (v1.4 as for this guide)
  • Open the Pi Imager and choose the Raspbian OS 64 bit and your micro-SD card and push on "WRITE" button.
  • Connect the backup flash drive, the keyboard, the mouse and the micro HDMI cable.
  • Put the microSD card on the RPI and power it on (connect a USB-C cable with min 4 A.).
  • Set your country, time zone etc to whatever you want.
  • Create the sand account
  • Skip the wifi config step
  • Update software
  • Restart the computer
  • Set the correct time, time zone and date
    • time zone have to be UTC
    sudo dpkg-reconfigure tzdata
    • Select None of the above
    • Select UTC
    • If required, set time and date (this should be required)
    sudo date -s '2017-02-03 01:35:55'
    • Adapt the date and time to your situation.
  • Use the raspberry configuration tool to desactivate the Auto login
sudo raspi-config
  • Select 1 System Options
  • Select S5 Boot / Auto Login
  • Select B3 Desktop GUI, requiring user to login
  • Select Finish
  • Accept to reboot the raspberry
  • Login as sand
  • Open a terminal window
  • Install the following packages
sudo apt install vim
sudo apt install vim-common
sudo apt install apache2
sudo apt install lm-sensors
sudo apt install imagemagick
sudo apt install ntp
sudo apt install openssh-client
sudo apt install openssh-server
sudo apt install netpbm
sudo apt install git
sudo apt install python3-serial
sudo apt install python3-dev
sudo apt install python3-rpi.gpio
sudo apt install python3-gpiozero
sudo apt install bc
sudo apt install iptables
sudo apt install gparted
sudo apt install gpsd
sudo apt install gpsd-clients
sudo apt install -y python3-kms++ python3-libcamera
sudo apt install -y python3-pyqt5 python3-prctl libatlas-base-dev ffmpeg
sudo apt install -y python3-picamera2
sudo pip install numpy --upgrade
sudo pip install --system datetime
sudo pip install pyyaml
sudo pip install skyfield
sudo pip install rawpy
sudo pip install matplotlib
sudo pip install datetime
sudo pip install astropy
sudo pip install photutils
sudo pip install scipy
sudo pip install LISC@git+

Installing NightMon applications

Latest available package release on github repository

  • To download NightMon apps:
mkdir git
cd git
git clone
  • Copy apps to system directory:
sudo cp -f /home/sand/git/nightmon/*.py /usr/local/bin/
sudo cp -f /home/sand/git/nightmon/*.bash /usr/local/bin/
sudo chmod a+x /usr/local/bin/*
  • Copy local configuration files
cp -f /home/sand/git/nightmon/ConfigFiles/* /home/sand
  • Create the data backup directory
mkdir /home/sand/data

Mount the usb stick on /home/sand/data

The usb stick will be the support to backup all the data. The backup will be done at 9 AM UT. That will be managed by the crontab.

  • Plug the usb stick in one of the RPI usb port. Type the following command:
sudo lsblk

You should see the usb drive on the sda1 drive

  • Edit fstab to mount the usb stick at /home/sand/data
sudo umount /dev/sda1
sudo su
echo "/dev/sda1 /home/sand/data vfat rw,user,exec,nofail,umask=000 0 0" >> /etc/fstab
sudo reboot


  • We assume that the file system on your usb stick is FAT. Please be sure to format the usb stick accordingly before the installation.
  • Be sure to replace /dev/sda1 with your actual device.


SSH server allows any remote SSH client to connect to the server to remotely control system programs from the command line or to download (upstream / downstream) data.

  • We must first be sure that the SSH server start automatically when the RPI boots.
sudo raspi-config
  • Select 3 Interface Options
    • SSH
      • Yes (to enable ssh)
  • ok
  • Finish
  • Set up your personal firewall to allow the SSH and http connections to pass through the firewall.
sudo iptables -I INPUT 1 -p tcp --dport 22 -j ACCEPT
sudo iptables -I INPUT 1 -p tcp --dport 80 -j ACCEPT
sudo iptables-save


sudo raspi-config
  • Select 3 Interface Options
    • I2C
      • Yes (to enable i2c)
  • ok
  • Finish

GPS configuration

  • Edit the gpsd configuration file
sudo vim /etc/default/gpsd
  • Set the following content
GPSD_OPTIONS="-F /var/run/gpsd.sock -n"

UPS hat (optional)

The UPS is a power battery backup. It will protect the system against power fluctuations and will allow the system to continue its ongoing tasks during short power failure.

  • To enable the up, edit the file /etc/rc.local
sudo vim /etc/rc.local
  • Add a line before the exit 0 with the following content:
/usr/local/bin/ &

Reboot the computer

sudo reboot

After the reboot, the UPS must be online. Try to remove the power connector. If the UPS hat is working properly, it should stay on for 60 sec and then shutdown. If not, your UPS hat is probably defective.

Automatic startup of observation script and data repository cleaning codes

This is the master code that operate the image acquisition and analysis. This code is started every 15 min using crontab

  • observe script
cd /home/sand/git/nightmon
chmod a+x *
sudo cp observe.service /etc/systemd/system
sudo systemctl enable observe.service
sudo systemctl start observe.service
  • Edit crontab
sudo crontab -e
  • chose editor 2. /usr/bin/vim.basic
  • type < i > and add the following content:
0 12 * * * /usr/local/bin/Clean_files.bash
  • Save and quit by typing: <escape> :wq

Apache server

We are using the Apache2 web server. This server allows browsing the database and look at the log file.

To activate the web server, we must:

  • activate userdir module
sudo a2enmod userdir
sudo service apache2 restart
  • Create the data directory and modify the permissions by doing:
sudo mkdir /var/www/html/data
sudo chmod a+rx /var/www/html/data
  • Edit the apache2 configuration file
sudo vim /etc/apache2/apache2.conf
  • Then type < i > to enter insert mode and add the following lines to the file
# added for nightmon
<Directory /var/www/html/data>
Options Indexes FollowSymLinks MultiViews
AllowOverride None
Require all granted
  • Then exit and save by typing: <escape> :wq
  • Restart the webserver
sudo service apache2 restart

Set up the wifi access point


  • In order to work as an access point, the Raspberry Pi needs to have the hostapd access point software package installed:
sudo apt install hostapd
  • Enable the wireless access point service and set it to start when your Raspberry Pi boots:
sudo systemctl unmask hostapd
sudo systemctl enable hostapd
  • In order to provide network management services (DNS, DHCP) to wireless clients, the Raspberry Pi needs to have the dnsmasq software package installed:
sudo apt install dnsmasq
  • Finally, install netfilter-persistent and its plugin iptables-persistent. This utility helps by saving firewall rules and restoring them when the Raspberry Pi boots:
sudo DEBIAN_FRONTEND=noninteractive apt install -y netfilter-persistent iptables-persistent

Set up the network router

The Raspberry Pi will run and manage a standalone wireless network. It will also route between the wireless and Ethernet network, providing internet access to wireless clients when the wired network interface is connected to the web.

Define the wireless interface IP configuration

The Raspberry Pi runs a DHCP server for the wireless network; this requires static IP configuration for the wireless interface (wlan0) in the Raspberry Pi. The Raspberry Pi also acts as the router on the wireless network. We give the router the first IP address in the network:

  • To configure the static IP address of the WiFi interface, edit the configuration file for dhcpcd with:
sudo vim /etc/dhcpcd.conf
  • Go to the end of the file and add the following:
interface wlan0
static ip_address=
nohook wpa_supplicant

Enable routing and IP masquerading

This section configures the Raspberry Pi to let wireless clients access computers on the main (Ethernet) network, and from there, to access the internet (if the wired interface is connected to the web). NOTE: If you prefer to block wireless clients from accessing the Ethernet network and the internet, skip this section.

  • To enable routing, i.e. to allow traffic to flow from one network to the other in the Raspberry Pi, create a file using the following command, with the contents below:
sudo vim /etc/sysctl.d/routed-ap.conf
  • File content:
# Enable IPv4 routing

Enabling routing will allow hosts from network to reach the LAN and the main router towards the internet. In order to allow traffic between clients on this foreign wireless network and the internet without changing the configuration of the main router, the Raspberry Pi can substitute the IP address of wireless clients with its own IP address on the LAN using a "masquerade" firewall rule.

The main router will see all outgoing traffic from wireless clients as coming from the Raspberry Pi, allowing communication with the internet. The Raspberry Pi will receive all incoming traffic, substitute the IP addresses back, and forward traffic to the original wireless client.

  • This process is configured by adding a single firewall rule in the Raspberry Pi:
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
  • Now save the current firewall rules for IPv4 (including the rule above) and IPv6 to be loaded at boot by the netfilter-persistent service:
sudo netfilter-persistent save

Filtering rules are saved to the directory /etc/iptables/. If in the future you change the configuration of your firewall, make sure to save the configuration before rebooting.

Configure the DHCP and DNS services for the wireless network

The DHCP and DNS services are provided by dnsmasq. The default configuration file serves as a template for all possible configuration options, whereas we only need a few. It is easier to start from an empty file.

  • Rename the default configuration file and edit a new one:
sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig
sudo vim /etc/dnsmasq.conf
  • Add the following to the file and save it:
interface=wlan0 # Listening interface
# Pool of IP addresses served via DHCP
domain=wlan # Local wireless DNS domain
# Alias for this router

The Raspberry Pi will deliver IP addresses between and, with a lease time of 24 hours, to wireless DHCP clients.

There are many more options for dnsmasq; see the default configuration file (/etc/dnsmasq.conf) or the online documentation for details.

Ensure wireless operation

Countries around the world regulate the use of telecommunication radio frequency bands to ensure interference-free operation. The Linux OS helps users comply with these rules by allowing applications to be configured with a two-letter "WiFi country code", e.g. US for a computer used in the United States.

In the Raspberry Pi OS, 5 GHz wireless networking is disabled until a WiFi country code has been configured by the user, usually as part of the initial installation process.

  • To ensure WiFi radio is not blocked on your Raspberry Pi, execute the following command:
sudo rfkill unblock wlan

This setting will be automatically restored at boot time. We will define an appropriate country code in the access point software configuration, next.

Configure the access point

  • Create the hostapd configuration file, located at /etc/hostapd/hostapd.conf, to add the various parameters for your wireless network.
sudo vim /etc/hostapd/hostapd.conf
  • Add the information below to the configuration file. This configuration assumes we are using channel 7, with a network name of nightmon, and a passphrase nightmonwifi. Note that the name and password should not have quotes around them. The passphrase should be between 8 and 64 characters in length.

Note the line country_code=CA: it configures the computer to use the correct wireless frequencies in Canada. Adapt this line and specify the two-letter ISO code of your country. See Wikipedia for a list of two-letter ISO 3166-1 country codes.

To use the 5 GHz band, you can change the operations mode from hw_mode=g to hw_mode=a. Possible values for hw_mode are:

a = IEEE 802.11a (5 GHz)
b = IEEE 802.11b (2.4 GHz)
g = IEEE 802.11g (2.4 GHz)
ad = IEEE 802.11ad (60 GHz)

Run your new wireless access point

  • Now restart your Raspberry Pi and verify that the wireless access point becomes automatically available.
sudo systemctl reboot

Once your Raspberry Pi has restarted, search for wireless networks with your wireless client. The network SSID nightmon should now be present, and it should be accessible with the password nightmonwifi.

If SSH is enabled on the Raspberry Pi, it should be possible to connect to it from your wireless client as follows, assuming the pi account is present: ssh sand@ or ssh sand@nightmon

Configure the network parameters of the raspberry pi

  • Edit the file /etc/dhcpcd.conf
sudo vim /etc/dhcpcd.conf
  • Uncomment the section related to the static ip configurations but set ip address to i.e.
# Example static IP configuration:
interface eth0
static ip_address=
static ip6_address=fd51:42f8:caae:d92e::ff/64
static routers=
static domain_name_servers= fd51:42f8:caae:d92e::1

Real time clock

We are using the DS3231 RTC module to keep the date and time after powering off the system.

  • You can run the following command on your Raspberry Pi to detect that you have correctly wired up your RTC device.
sudo i2cdetect -y 1

If you have successfully wired up your RTC circuit, you should see the ID #68 appear. This id is the address of the DS3231 RTC Chips. Once we have the Kernel driver up and running the tool will start to display UU instead, this is an indication that it is working as intended.

Setting up the Raspberry Pi RTC Time

With I2C successfully setup and verified that we could see our RTC circuit then we can begin the process of configuring the Raspberry Pi to use our RTC Chip for its time.

  1. To do this, we will first have to modify the Raspberry Pi’s boot configuration file so that the correct Kernel driver for our RTC circuit will be successfully loaded in.
  • Run the following command on your Raspberry PI to begin editing the /boot/config.txt file.
sudo vim /boot/config.txt
  • Within this file, you will want to add the following line to the bottom of the file.

Once you have added the correct line for your device to the bottom of the file you can save and quit out of it by pressing Esc, then :wq and then Enter.

With that change made we need to restart the Raspberry Pi, so it loads in the latest configuration changes.

  • Run the following command on your Raspberry Pi to restart it.
sudo reboot
  • Once your Raspberry Pi has finished restarting we can now run the following command, this is so we can make sure that the kernel drivers for the RTC Chip are loaded in.
sudo i2cdetect -y 1

You should see a wall of text appear, if UU appears instead of 68 then we have successfully loaded in the Kernel driver for our RTC circuit.

Now that we have successfully got the kernel driver activated for the RTC Chip and we know it’s communicating with the Raspberry Pi, we need to remove the fake hwclock package. This package acts as a placeholder for the real hardware clock when you don’t have one.

  • Type the following two commands into the terminal on your Raspberry Pi to remove the fake-hwclock package. We also remove hwclock from any startup scripts as we will no longer need this.
sudo apt-get -y remove fake-hwclock
sudo update-rc.d -f fake-hwclock remove

Now that we have disabled the fake-hwclock package we can proceed with getting the original hardware clock script that is included in Raspbian up and running again by commenting out a section of code.

  • Run the following command to begin editing the original RTC script.
sudo vim /lib/udev/hwclock-set

If you upgrade the operating system, you may need to redo the following step.

  • Find and comment out the following three lines by placing # in front of it as we have done below.
    • Find
    if [ -e /run/systemd/system ] ; then
    exit 0
    • Replace With
    #if [ -e /run/systemd/system ] ; then
    # exit 0
  • Once you have made the change, save the file by pressing Esc then :wq then Enter.

Syncing time from the Pi to the RTC module

Now that we have our RTC module all hooked up and Raspbian and the Raspberry Pi configured correctly we need to synchronize the time with our RTC Module. The reason for this is that the time provided by a new RTC module will be incorrect.

  • You can read the time directly from the RTC module by running the following command if you try it now you will notice it is currently way off our current real-time.
sudo hwclock -D -r
  • Now before we go ahead and sync the correct time from our Raspberry Pi to our RTC module, we need to run the following command to make sure the time on the Raspberry Pi is in fact correct. If the time is not right, make sure that you are connected to a Wi-Fi or Ethernet connection.
  • If the time displayed by the date command is correct, we can go ahead and run the following command on your Raspberry Pi. This command will write the time from the Raspberry Pi to the RTC Module. If the time displayed is wrong, skip to the next section (Syncing the Pi to the RTC on startup).
sudo hwclock -w
  • Now if you read the time directly from the RTC module again, you will notice that it has been changed to the same time as what your Raspberry Pi was set at. You should never have to rerun the previous command if you keep a battery in your RTC module.
sudo hwclock -r

Syncing the Pi to the RTC on startup

  • If we want the pi to sync with internet time on startup, we will need to enable ntp protocol. To do so, just write the following line in the terminal.
sudo timedatectl set-ntp 1
The activation of the ntp clock sync will not affect the RTC clock sync when the internet is unplugged.
  • If you want to set the date manually to the RTC clock, you can now do it by writing the following command (adapt the date and time to your situation):
sudo hwclock --set --date "8/11/2013 23:10:45"
sudo hwclock -s
You can make sure that it worked by typing:
  • Next, you will need to add the RTC device creation at boot by editing the /etc/rc.local file by running
sudo vim /etc/rc.local
and by adding the following line to the file just before the "exit 0":
sudo hwclock -s
Once you have made the change, save the file by pressing Esc then :wq then Enter.
  • We must restart the Raspberry Pi. To do this, type the following command into the terminal on your Raspberry Pi to restart it.
sudo reboot

Now, you should hopefully now have a fully operational RTC module that is actively keeping your Raspberry Pi’s time correct even when it loses power or loses an internet connection.

System reboot

Now all the relevant software are installed, in order to activate all newly added functionalities, restart the computer.

Optional stuff

D-LINK router configuration

The router is useful when NightMon is connected to the Internet and that the appropriate ports are open to take control of the instrument remotely. If the system is not connected to the internet, a simple network switch or hub is sufficient.

  • Router local IP:
  • Disable DHCP server and attribute Fixed IP as follow:
    • = raspberry pi
    • = SQM
    • 192.168.0.other = any other computer connected temporarily or permanently to the router
  • Create a virtual server to redirect port 2022 of the router toward SSH port 22 of
  • Do the same for port 2080 to allow web access redirection (port 80)
  • Create virtual server from port 2180 toward port 80 (webcam server). This redirection will allow a user to see the webcam image from the web even if the computer is off.