Meeting on Asteroids and Comets Europe 2006 May 14 st-moving asteroids Lightcurve photometry of fast-moving asteroids by simultaneous V- and I-band calibration of field stars by Richard Miles Golden Hill Observatory (MPC J77), United Kingdom

Observatory Setup

Methodology-1 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I)

Hipparcos Coverage

Hipparcos to V

V-I vs B-V

Methodology-2 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs

R-B Pairs Sky Distribution Sky Distribution of Hipparcos Red-Blue Pairs

Cl to V coeff. Transformation – Clear to V Transformation Coefficient

Cl to V calculated Transformation – Clear to V Magnitude

Methodology-3 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs 3) Calibrate unfiltered photometry (stars and asteroids)

Cl to V measured

Methodology-4 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs 3) Calibrate unfiltered photometry (stars and asteroids) 4) Simultaneous wide-field images in V and I-band

Methodology-5 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs 3) Calibrate unfiltered photometry (stars and asteroids) 4) Simultaneous wide-field images in V and I-band 5) Unfiltered images with narrow-field telescope

Methodology-6 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs 3) Calibrate unfiltered photometry (stars and asteroids) 4) Simultaneous wide-field images in V and I-band 5) Unfiltered images with narrow-field telescope 6) Determine V and (V-I) colours of stars near asteroid track

HIP HIP HIP x 1 minute stacked exposures 6-cm aperture + V filter

HIP HIP HIP Track of 2000 BD19 79 x 1 minute stacked exposures 6-cm aperture + V filter

Inset images using 28-cm aperture + no filter

a d ef g h i j m n o p q r s t

a

Methodology-7 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs 3) Calibrate unfiltered photometry (stars and asteroids) 4) Simultaneous wide-field images in V and I-band 5) Unfiltered images with narrow-field telescope 6) Determine V and (V-I) colours of stars near asteroid track 7)Carry out aperture photometry or PSF photometry of fast- moving asteroid relative to an ensemble of stars in the same field - Difficult - May need to stack groups of images (Astrometrica, Lymm software) to get adequate SNR for asteroid.

Methodology-8 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs 3) Calibrate unfiltered photometry (stars and asteroids) 4) Simultaneous wide-field images in V and I-band 5) Unfiltered images with narrow-field telescope 6) Determine V and (V-I) colours of stars near asteroid track 7)Carry out aperture photometry or PSF photometry of fast- moving asteroid relative to an ensemble of stars in the same field - Difficult - May need to stack groups of images (Astrometrica, Lymm software) to get adequate SNR for asteroid. 8) Calculate V-magnitude zeropoint of unfiltered images using ensemble of stars. May require photometry of trailed stars using tilted elliptical aperture with AstPhot32 software (Stefano Mottola) or Lymm8 software (John Saxton)

AstPhot32 Software Stefano Mottola

Lymm software John Saxton Features: Script-based running in Fortran Pattern recognition Models track of asteroid Tracks and stacks images (if required) Aperture or PSF photometry on calculated asteroid positions NEW! - Photometry on single images or on user-defined stacks NEW! - Novel sky background correction

2005 WC1 (diameter 500m approx) 2005 Dec h UT

2005 WC1

Sky Background Correction

Sky Background Correction

Effect of PA

2000 BD19

130 B&W (130) Elektra – Composite Lightcurve

130 Electra Composite

130 Phase Curve

Phase brightening

ACKNOWLEDGMENTS Stefano Mottola – AstPhot32 photometry software John Saxton – Lymm photometry software Norman Walker – Provision of V and I filters Acknowledgments

THANKS FOR YOUR ATTENTION End of talk