Useful Astronomy Formulas
| Parameter | Formula |
|---|---|
| Image Scale (arcsec/pixel) | (206.265 * Camera Pixel (um) * Camera Binning) / (Telescope Focal Length (mm) * Reducer) |
| Sensor Width (mm) | (Number Sensor Pixels Wide * Camera Pixel (um)) / (1000) |
| Sensor Height (mm) | (Number Sensor Pixels High * Camera Pixel (um)) / (1000) |
| Image Circle (mm) | Square Root of (Sensor Width * Sensor Width) + (Sensor Height * Sensor Height) |
| Field Of View (arcmin) | Width = Image Scale * Number Sensor Pixel Wide / 60 Height = Image Scale * Number Sensor Pixel High / 60) |
| Focal Ratio | Telescope Focal Length (mm) * Reducer / Telescope Aperture (mm) |
| Optimum Pixel Size (um) @ Wavelength(nm) |
Telescope Focal Length (mm) * Reducer * Wavelength (nm) / (Telescope Aperture (mm) * 2000) NOTE: 10 Angstroms = 1 Nanometer |
| Dawes Limit | 116 / Telescope Aperture (mm) |
| Rayleight Limit | 138 / Telescope Aperture (mm) |
| Limiting Magnitude | 7.7 + [ 5 * (Base 10 Log(Telescope Aperture (mm)/10))] |
| Telescope Light Gain Compared to 7mm pupil |
(Telescope Aperture (mm) * Telescope Aperture (mm)) / (7 * 7) |
| Seeing Scale | Exceptional 0.17 to 0.50 arcsec/pixel Good 0.33 to 1.00 arcsec/pixel Okay 0.67 to 2.00 arcsec/pixel Poor 1.33 to 2.50 arcsec/pixel Very Poor 1.67 to 3.00 arcsec/pixel |
| Telescope Light Gain Compared to 7mm pupil |
(Telescope Aperture (mm) * Telescope Aperture (mm)) / (7 * 7) |