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 Convert visual mags/arcsecond² to cd/m² 0.00 mag/arcsec² = 1.080×105 cd/m² = 1.080×108 mcd/m² = 1.080×1011 µcd/m² ( 108000000000.00 µcd/m² ) Using the formula: [value in cd/m2] = 10.8×104 × 10(-0.4*[value in mag/arcsec2]) OpenOffice formula: =108000*POWER(10;(-0.4*mags)) MS-Excel formula: =108000*POWER(10,(-0.4*mags)) Where mags is the cellname that contains the mag/arcsec2 reading. Convert cd/m² to visual mags/arcsecond² Using the formula: [value in mag/arcsec2] = Log10([value in cd/m2]/108000)/-0.4 OpenOffice formula: =(LOG(cdm2/108000))/-0.4)) Where cdm2 is the cellname that contains the cd/m2 reading. ```This formula was derived from conversations on the Yahoo-groups darksky-list Topic: [DSLF] Conversion from mg/arcsec^2 to cd/m^2 Date range: Fri, 1 Jul 2005 17:36:41 +0900 to Fri, 15 Jul 2005 08:17:52 -0400 PDF summary of conversation.``` Percentages to mpsas to percentages `````` The direction of darkening/lightening is included the calculation. For example: an increase of 0.5mpsas is 36.90% darker. a decrease of 0.5mpsas is 58% brighter. You can use the following formulas: Percent to mpsas: mpsas =-2.5*LOG(1 + pct) Ex. for darkening of 36.9%: mpsas = -2.5*log(1 - 0.369) = .5 mpsas mpsas to percent: 10^(mpsas/-2.5)-1 (Open office formula) POWER(10,(mpsas/-2.5))-1 Ex. for darkening of 0.5mpsas: pct = 10^(0.5/-2.5)-1 = 10^(-0.2)-1 = 0.631 -1 = -36.9% ``````