import astropy.units as u from astropy.coordinates import SkyCoord def hot_fov(temp_celsius, focal_length_mm, sensor_width_mm): # Thermal expansion coefficient for aluminum (23e-6) thermal_expansion = 1 + (23e-6 * (temp_celsius - 20)) adjusted_focal = focal_length_mm * thermal_expansion tfov_rad = (sensor_width_mm / adjusted_focal) tfov_deg = tfov_rad * (180 / 3.14159) return tfov_deg print(hot_fov(20, 600, 23.5)) # 2.24° print(hot_fov(35, 600, 23.5)) # 2.23° (notice the slight shrink)
This script proves that on a hot day, your telescope’s focal length actually increases , reducing your true FOV by fractions of a degree. For mosaic planning, this matters. To finish, here is your daily driver workflow using a hot astro FOV calculator . astro+fov+calculator+hot
In the amateur astronomy community, the term “hot” has two meanings. First, it refers to the latest trending equipment—those newly released, ultra-wide eyepieces (like the 100° APM or 120° Explore Scientific) and high-quantum-efficiency CMOS cameras that everyone is talking about on Cloudy Nights. Second, it refers to the literal thermal noise in your sensor. To tame both, you need an enough to handle complex optical trains. import astropy