A method for determining the V magnitude of asteroids from CCD images

TL;DR

This paper presents a differential photometry method to determine asteroid V magnitudes using CMC14 catalog data, achieving accuracy of ±0.05 mag, improved to ±0.03 mag with multiple stars, and noting limitations near the galactic plane.

Contribution

The paper introduces a practical, catalog-based method for asteroid magnitude estimation that simplifies and improves accuracy over traditional photometry techniques.

Findings

Achieves ±0.05 mag accuracy using CMC14 stars

Improves to ±0.03 mag with multiple comparison stars

Less accurate near the galactic equator due to reddening and crowding

Abstract

We describe a method of determining the V magnitude of an asteroid using differential photometry, with the magnitudes of comparison stars derived from Carlsberg Meridian Catalogue 14 (CMC14) data. The availability of a large number of suitable CMC14 stars enables a reasonably accurate magnitude (\pm0.05 mag) to be found without having to resort to more complicated absolute or all-sky photometry. An improvement in accuracy to \pm0.03 mag is possible if an ensemble of several CMC14 stars is used. This method is expected to be less accurate for stars located within \pm10deg of the galactic equator owing to excessive interstellar reddening and stellar crowding.