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4 bortle scale astronomy news items found

Dark sky astronomy locations guide

Finding a dark sky location for astronomy begins with understanding what makes a sky dark. A dark sky is one where artificial light is minimal or absent, allowing celestial objects to appear with clarity and contrast. This level of darkness isn’t judged by personal perception but by measured values. One of the main systems used is the Bortle Scale, which ranks sky...

Large telescopes vs light pollution

For amateur astronomers, bigger telescopes mean better views—plain and simple. While professional observatories have massive 10-meter mirrors, most of us are working with something in the 8" to 24" range, with some die-hard enthusiasts pushing up to 30" for visual observing. A 17" or 24" Dobsonian, for example, is a serious deep-sky machin...

Optolong L-Para filter

Optolong has introduced the L-Para (L-Parallels), a dual narrowband 10nm light pollution filter tailored to meet the demanding requirements of astrophotographers. With a full width at half maximum (FWHM) of 10nm for the OIII (500.7nm) and H-Alpha (656.3nm) emission lines, the filter achieves a transmittance exceeding 85% in systems with focal ratios of F2 and above. Thi...

The Bortle dark-sky scale explained

The Bortle Dark-Sky Scale, named after its creator John E. Bortle, is a nine-level numeric scale that measures the night sky's brightness and the visibility of celestial objects. Bortle, an experienced amateur astronomer, introduced this scale in 2001 to help fellow stargazers quantify the quality of their observing sites. The scale ranges from Class 1, representing...