1:45 PM - 3:15 PM
[O11-P126] Study on the measurement of seeing using solar images
Keywords:Sun, Seeing
1.Purpose
This study aimed to select a sunspot observation site and evaluate seeing conditions at our school in Nakano, Tokyo. Using a custom-developed program, we quantified seeing from solar images and tracked its temporal variation.
2.Observation
The equipment is listed in Table 1, and conditions at Fuji High School are in Table 2. The diffraction limit, calculated using L = 1.22 × (λ/D), was 2.09″, and one pixel corresponded to 3.707″. We recorded 10-second solar videos (110 fps, 12-bit) at two locations, rooftop and poolside—five times per day over five days.
3.Quantification of Seeing
① The solar image’s center and radius were detected using the Hough Transform. A brightness profile near the edge was created and spatially differentiated.
② The solar limb was defined from the peak of the derivative. The distance from this limb to the image center was compared with the theoretical value.
③ The standard deviation of these differences across each video was calculated as a measure of seeing. Pixel rows from various directions were used (1,360 points per image). No dark or flat-field correction was applied.
4.Results
The magnitude of the fluctuations when the theoretical solar radius is R is as follows:
- Rooftop R ± 8.86″
- Poolside: R ± 8.97″
As shown in Table 3, the seeing conditions at both locations were nearly identical, with a difference of only 0.11″.
5.Discussion
The rooftop had slightly lower fluctuation, but it was within pixel resolution limits, indicating no significant difference between sites. Figure 4 shows 10-point moving averages, revealing irregular variation. High-speed recording at 110 fps showed that seeing changes faster than 10 ms.
Figure 5 visualizes brightness profiles along the solar limb in 3D. Steeper brightness drops (wider gaps in plots) indicate better seeing. This visualization confirmed the differences between good and poor seeing conditions.
In conclusion, no major difference was observed between rooftop and poolside. Our method allows seeing analysis over time and shows that either location is viable for solar observation.
6.Future Prospects
Challenges include limitations in camera sensitivity. Future improvements involve narrowing the wavelength using filters and scaling the image. Flat-field and dark corrections will improve accuracy.
This study compared only two sites. Future work will include various environmental factors (pressure, wind, etc.) and broader seasonal/location comparisons.
The program can also be used for nighttime observations, expanding its application beyond daytime solar studies. These findings may also benefit fields that require high-resolution imaging beyond astronomy.
7.References
[1] Miyara, A., et al., 2017, Proceedings of Symposium on Techniques in Astronomy, No.37.
[2] ASJ glossary of astronomy, The Astronomical Society of Japan, https://astro-dic.jp/
[3]H.Socas-Navarro et al., 2005, Publications of the Astronomical Society of the Pacific,117, 837, pp.1296-1305.
This study aimed to select a sunspot observation site and evaluate seeing conditions at our school in Nakano, Tokyo. Using a custom-developed program, we quantified seeing from solar images and tracked its temporal variation.
2.Observation
The equipment is listed in Table 1, and conditions at Fuji High School are in Table 2. The diffraction limit, calculated using L = 1.22 × (λ/D), was 2.09″, and one pixel corresponded to 3.707″. We recorded 10-second solar videos (110 fps, 12-bit) at two locations, rooftop and poolside—five times per day over five days.
3.Quantification of Seeing
① The solar image’s center and radius were detected using the Hough Transform. A brightness profile near the edge was created and spatially differentiated.
② The solar limb was defined from the peak of the derivative. The distance from this limb to the image center was compared with the theoretical value.
③ The standard deviation of these differences across each video was calculated as a measure of seeing. Pixel rows from various directions were used (1,360 points per image). No dark or flat-field correction was applied.
4.Results
The magnitude of the fluctuations when the theoretical solar radius is R is as follows:
- Rooftop R ± 8.86″
- Poolside: R ± 8.97″
As shown in Table 3, the seeing conditions at both locations were nearly identical, with a difference of only 0.11″.
5.Discussion
The rooftop had slightly lower fluctuation, but it was within pixel resolution limits, indicating no significant difference between sites. Figure 4 shows 10-point moving averages, revealing irregular variation. High-speed recording at 110 fps showed that seeing changes faster than 10 ms.
Figure 5 visualizes brightness profiles along the solar limb in 3D. Steeper brightness drops (wider gaps in plots) indicate better seeing. This visualization confirmed the differences between good and poor seeing conditions.
In conclusion, no major difference was observed between rooftop and poolside. Our method allows seeing analysis over time and shows that either location is viable for solar observation.
6.Future Prospects
Challenges include limitations in camera sensitivity. Future improvements involve narrowing the wavelength using filters and scaling the image. Flat-field and dark corrections will improve accuracy.
This study compared only two sites. Future work will include various environmental factors (pressure, wind, etc.) and broader seasonal/location comparisons.
The program can also be used for nighttime observations, expanding its application beyond daytime solar studies. These findings may also benefit fields that require high-resolution imaging beyond astronomy.
7.References
[1] Miyara, A., et al., 2017, Proceedings of Symposium on Techniques in Astronomy, No.37.
[2] ASJ glossary of astronomy, The Astronomical Society of Japan, https://astro-dic.jp/
[3]H.Socas-Navarro et al., 2005, Publications of the Astronomical Society of the Pacific,117, 837, pp.1296-1305.