Applying Transformation and Extinction to Magnitude Estimate—How Much Does It Improve Results? (Abstract)

Volume 46 number 2 (2018)

Gordon Myers

5 Inverness Way, Hillsborough, CA 94010; GordonMyers@hotmail.com

Ken Menzies

318A Potter Road, Framingham, MA 01701; kenmenstar@gmail.com

Abstract

(Abstract only) Photometrists regularly ask the question as to whether they should apply transformation and extinction corrections to their magnitude estimates. How much do these corrections improve the accuracy of their reported standard magnitudes? How much effort is involved in making these corrections? We quantify the significance of these corrections based on the characteristics of equipment (e.g., filter, CCD and field of view) and the conditions of the observation (e.g., airmass). Specific examples are presented for both CCD and DSLR systems. We discuss the best practices that one should follow to improve their reported magnitudes and the AAVSO tools (vphot, Transform Generator, Transform Applier) that facilitate an easy correction to your results. It is found that magnitude corrections for CCD observers are small but significant for most amateur equipment, and critical for most DSLR observers.