Conversion Calculator - NELM (V) to MPSAS (B) systems

K. Fisher fisherka@csolutions.net Rev. 8/2006

Math Appendix

• Convert NELM (V mags) to MPSAS (B) sky brightness

• Formula: B_mpsas = 21.58 - 5 log(10^(1.586-NELM/5)-1)
• Source: Schaefer, B.E. Feb. 1990. Telescopic Limiting Magnitude. PASP 102:212-229 http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1990PASP..102..212S

• Convert MPSAS (B) sky brightness to NELM (V mags)

• Formula: NELM=7.93-5*log(10^(4.316-(Bmpsas/5))+1)
• Source: Olof Carlin, Nils. About Bradley E. Schaefer: Telescopic limiting Magnitudes . . . . Web page discussion of brightness in Schaefer (1990) and Clark (1994). http://w1.411.telia.com/~u41105032/visual/Schaefer.htm (accessed 7/2003)

• Convert extended object size (arcmins) and apparent brightness (V) to MPSAS

• Formula: objB_mpas = objMagnitude + (2.5 * (Log10((PI() / 4) * objMajorAxis_arcsec * objMinorAxis_arcsec)))
• Sources:
  Clark, R.N., 1990. Appendix E in Visual Astronomy of the Deep Sky, Cambridge University Press and Sky Publishing.http://www.clarkvision.com/visastro/appendix-e.html
  Covington, M. (1998, 2d). Appendix A, Astrophotography for Amateurs. pp. 259-261 http://www.covingtoninnovations.com/

• Compute an extended object's contrast index

• Formula: ContrastIndex = -0.4 * (objB_mpas - B_mpas)
• Source: Clark, R.N., 1990. Appendix E in Visual Astronomy of the Deep Sky, Cambridge University Press and Sky Publishing.http://www.clarkvision.com/visastro/appendix-e.html

• Test data

• See Clark, R.N., 1990. Appendix E in Visual Astronomy of the Deep Sky, Cambridge University Press and Sky Publishing.http://www.clarkvision.com/visastro/appendix-e.html

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Prepared K. Fisher fisherka@csolutions.net rev. 8/6/2006