11:30 〜 11:45
[PEM13-09] Optical calibration of a commercial digital camera for auroral studies
キーワード：オーロラ、光学較正、デジタルカメラ、市民科学
As an activity of citizen science, pictures of auroras taken by photographers using commercial digital cameras have been used for scientific research. Such digital images contain a lot of background noise in various wavelengths, unlike professional optical data captured with a narrow-band filter. However, commercial digital cameras have three RGB channels and can capture what we see with our eyes in full color. This capability often enables us to identify characteristics of optical phenomena that are difficult to notice in monochromatic data (MacDonald et al., 2018; Shiokawa et al., 2018; Nanjo et al., 2024; Nanjo & Shiokawa, 2024). Furthermore, it has been suggested that the colors of auroras in images can be used to estimate the average energy of electrons responsible for pulsating auroras (Nanjo et al., 2021). Thus, observations by photographers would have the potential to play an essential role in the scientific research of auroras.
This study hypothesizes that among the RGB color channels, the blue channel corresponds to the first negative band of nitrogen molecular ions, while the green channel corresponds to the oxygen green line. It further investigates whether the B/G ratio increases in the equatorial region in the morning sector, suggesting a positive correlation between this ratio and the characteristic energy of precipitating electrons. To explore this question in detail, a commercial digital camera (Nikon D5) was installed at the Ramfjordmoen field station near Tromsø, Norway, to examine how RGB count values correspond to Rayleigh values measured by a nearby photometer.
The results showed that, as discussed by Nanjo et al. (2021), the blue channel correlates with the Rayleigh values at 427.8 nm, while the green channel correlates with those at 557.7 nm. Additionally, the Nikon D5 was calibrated at the National Institute of Polar Research before installation in Tromsø. Further details on these calibration experiments will be presented in the talk.
This study hypothesizes that among the RGB color channels, the blue channel corresponds to the first negative band of nitrogen molecular ions, while the green channel corresponds to the oxygen green line. It further investigates whether the B/G ratio increases in the equatorial region in the morning sector, suggesting a positive correlation between this ratio and the characteristic energy of precipitating electrons. To explore this question in detail, a commercial digital camera (Nikon D5) was installed at the Ramfjordmoen field station near Tromsø, Norway, to examine how RGB count values correspond to Rayleigh values measured by a nearby photometer.
The results showed that, as discussed by Nanjo et al. (2021), the blue channel correlates with the Rayleigh values at 427.8 nm, while the green channel correlates with those at 557.7 nm. Additionally, the Nikon D5 was calibrated at the National Institute of Polar Research before installation in Tromsø. Further details on these calibration experiments will be presented in the talk.