An approximation exists for the conversion between NELM and MPSAS. You can use an NELM converter[5] created by SQM user K. Fisher to do that conversion, or the chart shown in Figure 2.2 and Equations (2.2) and (2.3). Figure 2.2: Mpsas vs NELM Convert NELM (V mags) to MPSAS (...
but buggered if I am going to just plonk myself at the first open grassy field I come across. I will be doing more work to locate a site that will give the best transparency. Otherwise I am just cheating myself and flipping the bird...
I think most of us still reading this thread know how to incorporate the SQM number + seeing +transparency to get an idea of the quality of the night. In fact most of us don't need to know any of these to gauge how the night is rated. However, if I were thinking about traveling ...