Development of an All-sky Camera for The Indonesian Sky Patrol Network

We developed the All-Sky Camera using a CMOS sensor, which is integrated with various other supporting devices to optimize image and video recordings. In general, CMOS cameras are not equipped with a cooling system, which can cause increased noise. Therefore, our design is equipped with an external cooling system to keep the temperature stable at night or during the day. In addition, our designs are also equipped with various other sensors, such as rain sensors, cloud sensors, light sensors, and sensors for environmental conditions such as pressure, temperature, and humidity. The development of the All-Sky Camera will also be used as a tool to monitor the sky throughout Indonesia with the Indonesian Sky Patrol Network (https://allskycam.or.id/). As a result, we managed to record several astronomical phenomena, such as meteors and space debris. For future scientific needs, the all-sky camera that we have developed is also used to monitor changes in light pollution and identify sources of light pollution, as well as the quality of the atmosphere at the ITERA Lampung Astronomical Observatory Environment (OAIL).


Introduction
The All-Sky Camera has fisheye lenses and CCD or CMOS detectors.It can be used to monitor changes in sky brightness caused by artificial light pollution around the location.It can also detect clouds, airglow, sky glow, traces of aircraft, satellites, space debris falling to the Earth, and meteors.Since the 1960s and 1970s, cameras with wide-field optics and mostly fisheye lenses or convex mirrors [1] have been used to collect data on fireballs and recover meteorites.Meteor observations are frequently done nowadays with video cameras [2], i.e., the development of automatic all-sky cameras for capturing bright meteor trails using a DSLR camera [3].The need to monitor sky conditions at an observatory site is to assess changes in star extinctions through photometry measurements of astronomical objects [4].By proper scaling methods, the camera gives a fairly well-defined sky area map occurring within a circle of 500 km radius and along the lengths of arcs, i.e., geomagnetic east and west, to distances of 10th Asian Physics Symposium (APS 2023) Journal of Physics: Conference Series 2734 (2024) 012027 IOP Publishing doi:10.1088/1742-6596/2734/1/012027 2 about 1200 km.These radii are based on an estimated lower border height of 100 km with curved earth considerations.Another purpose for which it can be used is for public outreach and education.The All-Sky Camera can display planet movement in the ecliptic plane, diurnal sky rotation, and zodiacal light and serve as a medium for explaining the most fundamental science of astronomy [5].

The Development of an All-sky Camera Description System
The camera will operate in equatorial latitudes (Indonesia) with unstable weather conditions throughout the season.A special effort has been made to design a rugged instrument capable of withstanding high winds, humid, wet conditions, and extreme temperature changes.Our all-sky camera development comprises five main parts: camera assembly, field of view (FOV) calibration, device support system, camera housing assembly, and control assembly.

Camera Assembly
The ZWO ASI178MM camera has a 1/1.8"CMOS sensor IMX178 with SONY STARVIS and Exmor-R Technology to produce low-noise but still high-sensitivity images.The back-illuminated sensor reaches a QE peak of 81% with sensitivity across all the visible light, infrared, and part of the ultraviolet between 300 and 400 nm.ZWO ASI178MM has a 14-bit ADC, low read noise, and high sensitivity, so it will make a great camera that can be used for several types of observation, including all-sky observation.See Table 1 for more detailed specifications.We can determine the true field of view of the imaging system by using a star position known at the time of the shooting and the radius distance from the image center.The straight line in Figure 1.(i) shows the relationship between the altitude of the star and the distance from the center of the image, and Figure 1.(ii) shows the stars used to calibrate the field of view.We can determine the true field of view using this linear equation and the variable of the maximum point at which the sky boundary is observed.Our calculation yields 170.26°, and this result follows the specifications of the lens used, which is 170 degrees.

Device Support System
The Device Support System consists of several components, as shown in Figure 2 and Figure 3, as follows: a. Weather Sensor There are several sensors that we install in our automatic weather stations.We generally use the mySQM+ software made by Robert Brown and an ESP32 microcontroller.This module uses the BME-280 sensor to measure temperature, humidity, and pressure.This sensor is known to be cheap and quite sensitive.We installed it outside the housing and covered it with a Stevenson screen to protect it from direct heat from the sun.We made an anemometer with a 3D printer with a heat-resistant PETG filament to measure wind speed.Then, use the hall effect sensor KY-024 with magnets to calculate wind speed.To determine the wind direction, we used the AS5600 magnetic sensor.distance from image center and star altitude relation b. Rain Sensor We also added a raindrop sensor.This sensor aims to determine whether it is raining and how heavy it is.If there are raindrops on the sensing pad, the resistance of the module will change.
If this value changes, the voltage will drop, and the sensor will signal that there are raindrops on the sensing pad.We also read the voltage output from this sensor; the smaller the voltage value, the heavier the rain.c.Infrared Sensor (Cloud Sensor) To measure how covered the clouds above are, we used the MLX90614 non-contact infrared temperature sensor module.This sensor reads two types of temperature: ambient temperature (Sky-Ambient) and sky temperature (Sky-Object).The coverage of this sensor is 90 degrees, directed to the zenith.Then, by comparing the Sky-Object and Sky-Ambient temperature values, we can determine the condition of the clouds in the sky.We can also do cloud modelling with these two sensor outputs in the software.Ten variables can be changed to determine the value according to the local conditions of the observatory.

d. Lux Sensor
We use TSL2591 as a lux sensor.The TSL2591 is a high-dynamic-range digital light sensor.It has a dynamic range of around 600 million to 1.It also has an effective maximum of around 88000 lux.This sensor has an extensive range because it has a configurable gain value.It is also sensitive to low light conditions, so it can be used as a sky quality meter.e. Camera Housing Assembly The camera housing assembly is made of Acrylonitrile Butadiene Styrene (ABS), which makes it more durable and heat resistant.The dimensions of the camera housing assembly are 150 x 250 x 130 mm.A ZWO 178MM camera with Fisheye Lens is installed in the box, along with other device supporting systems such as fan control, a dew point fan, a 5V power supply, a Raspberry Pi 3B+, a Raspberry Pi cooling fan, an exhaust fan, a voltage step down module, a weather station control board, a rain sensor, a TSL2591 lux sensor, and an MLX90614 IR sensor, as shown in Figure 2. We use a borosilicate glass dome to protect the camera.The housing must be waterproof and splashproof, except for the heat vents (in and out).

Control Assembly
To control and log capabilities, we use the Raspberry Pi 3B+ (see Figure 4).We use Thomas Jacquin's all-sky camera software to control and log the images, including generating time-lapses, keograms, and star trails (see Figure 5).We use mySQM+ (R Brown) firmware to manage all of our weather, cloud, and SQM sensors.We also use the mySQM+ software installed on the Raspberry Pi to log the weather station data sent from the ESP32 microcontroller through the Wi-Fi network.Everything is set to be automatic, including logging.We only use 64GB of MicroSD for Raspberry Pi storage, so we only have image logs for about 30 days locally.It generates about 1.3 GB of each image, video, keogram, and star trail data.We must back up every few weeks to more extensive storage, i.e., cloud storage or a desktop computer.If our Raspberry Pi is connected to the internet through Wi-Fi or a LAN network, we can connect it through VNC to update the configuration of the All-Sky camera or the weather station remotely.All logs are automatically saved on the Raspberry Pi for the weather station.Because it uses the TCP/IP protocol, we can retrieve weather data from other devices connected to the same Wi-Fi or network as the ESP32 microcontroller from mySQM+.We can also integrate it with ASCOM to write FITS file headers from telescope observations or save the logs in other places besides the main Raspberry Pi.See Figure 6, the image above shows (i) the view from the all-sky camera, (ii) the satellite image (visual), and (iii) the irradiance data from the VIIRS satellite.We can identify several sources of light pollution.In the image above, x is the location of the camera.We can see that: (a) one region is brighter than the other.By looking at the VIIRS irradiance map and also a map from the satellite, it can be seen that there are many sources of light pollution in that direction, especially from the ITERA Public Lecture Building and several laboratory buildings in the area (a) plus the direction from downtown Bandar Lampung (direction of Way Halim and Sukarame).For the light pollution source (b), we know that there is a very bright street lamp at the front gate of ITERA.The source of light pollution (c) is the construction site of one of the new buildings in ITERA.

Sky Patrol Network
Several institutions or groups have demonstrated the regional networks of all-sky cameras [6,7,8,9].The Indonesian Sky Patrol Network (ISPN) was formed on August 2, 2022, as a result of a collaboration between the ITERA Lampung Astronomical Observatory (OAIL) and the Surabaya Astronomy Club (SAC).ISPN currently has seven members who are managed individually by institutions in East Java, Lampung, DIY Yogyakarta, Central Kalimantan, and East Nusa Tenggara.The Allskycam position points are managed by the Indonesian Sky Patrol Network (ISPN) and can be accessed on the website https://allskycam.or.id/.Furthermore, the mission of establishing the Indonesian Sky Patrol Network (ISPN) is to patrol the sky by inviting all observatories and astronomical communities in Indonesia to use the All-Sky Camera.Each member's primary responsibilities are as follows: • Monitoring the Indonesian sky, particularly for falling objects such as meteors or space debris The debris of the burning CZ-5B rocket that lit up the sky of Sumatra was successfully detected in the north by the All-Sky Camera that we developed on the night of July 30, 2022, at 23:48 WIB (see Figure 7).This camera records the sky every 30 seconds.The dotted line in the image represents the trace of the CZ5B rocket body breaking apart due to burning in Earth's atmosphere.Three images resulting from the All-Sky Camera captured the debris as it moved from the southwest to the north for 1 minute and 30 seconds  The other observation results such as meteors passing through the atmosphere were also successfully identified using the All Sky Camera that we developed as seen in Figure 8 and Figure 9

Conclusion
In the last couple of months, an all-sky camera that we have developed using a CMOS sensor and other device-supporting systems has been very successfully tested in Indonesia based on optical observations and all-sky imaging.On the other side, the first stages of the development of our network allow us to reach the following conclusions: • Generally, CMOS sensors have produced high noise because of unstable thermal conditions on the chip because it doesn't have a cooling system.We added an external cooling system to keep the temperature inside the box still cool.For future advances in the development of the all-sky camera, we will use CCD chips to make possible the development of a more accurate all-sky camera.• The all-sky camera using a CMOS sensor has high efficiency, making it an excellent system for sky patrol.The system has excellent performance and low-cost maintenance.We successfully detected space debris and meteors that crossed into the Indonesian sky.• We need more prototypes to be installed from Sumatra to Papua or expand the membership network that already has All-Sky Camera to cover the Indonesian sky.So that it can be used as an early warning system for disaster mitigation from space objects • The all-sky camera system has a valuable additional utility.Its application is to other fields such as light pollution, airglow, atmospheric conditions, cloud movement, solar system objects, and other basic astronomical observations.This fact can allow the development of these lowcost all-sky cameras worldwide, having important implications for the dark sky campaign.

Figure 1 .
Figure 1.(i) Field of view calibration using several stars, (ii) Star used to calibrate Field of View2.3.Device Support SystemThe Device Support System consists of several components, as shown in Figure2and Figure3, as follows:a.Weather Sensor There are several sensors that we install in our automatic weather stations.We generally use the mySQM+ software made by Robert Brown and an ESP32 microcontroller.This module uses the BME-280 sensor to measure temperature, humidity, and pressure.This sensor is known to be cheap and quite sensitive.We installed it outside the housing and covered it with a Stevenson screen to protect it from direct heat from the sun.We made an anemometer with a 3D printer with a heat-resistant PETG filament to measure wind speed.Then, use the hall effect sensor KY-024 with magnets to calculate wind speed.To determine the wind direction, we used the AS5600 magnetic sensor.

Figure 2 .Figure 3 .
Figure 2. View into the camera box and other device-supporting systems

Figure 7 .
Figure 7.The All-Sky Camera records the trace of a debris long march 5B CZ-5B (Chang Zeng/Long March 5B) rocket.

Figure 8 .
Figure 8. All-Sky Camera at SAC records the Bright Meteor on July 26 2022 at 22:04 WIB.

Figure 9 .
Figure 9. All-Sky Camera at ITERA records a Perseid Meteor on August 16 2022 at 21.51 WIB

Table 1 . Camera technical specifications Parameter Value
Chinese heavyweight rocket launched from the Wenchang Space Launch Site on July 24, 2022, to deliver the Wentian laboratory module to China's Tiangong Space Station.According to US Space Command, the falling object is a piece of the 23-ton CZ-5B rocket, which exploded in flames as it flew at breakneck speed through the Earth's atmosphere.One part of this rocket began burning over the Indian Ocean around 4:45 p.m. (11:45 p.m. local time) after being stuck in low Earth orbit for several days.