Download presentation
Presentation is loading. Please wait.
1
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
2
Observatory Setup
3
Methodology-1 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I)
4
Hipparcos Coverage
5
Hipparcos to V
6
V-I vs B-V
7
Methodology-2 Observing Methodology 1) Utilise Hipparcos stars as secondary references in V (and I) 2) Calibrate using Hipparcos red-blue pairs
8
R-B Pairs Sky Distribution Sky Distribution of Hipparcos Red-Blue Pairs
9
Cl to V coeff. Transformation – Clear to V Transformation Coefficient
10
Cl to V calculated Transformation – Clear to V Magnitude
11
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)
12
Cl to V measured
13
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
14
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
15
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
16
HIP 55101 HIP 55503 HIP 55182 79 x 1 minute stacked exposures 6-cm aperture + V filter
17
HIP 55101 HIP 55503 HIP 55182 Track of 2000 BD19 79 x 1 minute stacked exposures 6-cm aperture + V filter
18
Inset images using 28-cm aperture + no filter
23
a d ef g h i j m n o p q r s t
24
a 10.86 14.85 14.59 12.59 14.01 10.82 11.85 13.16 13.12 13.29 13.70 15.45 14.82 12.66 12.86
25
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.
26
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)
27
AstPhot32 Software Stefano Mottola
28
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
29
2005 WC1 (diameter 500m approx) 2005 Dec 06 23.8-24.8h UT
31
2005 WC1
34
Sky Background Correction
35
Sky Background Correction
36
Effect of PA
37
2000 BD19
38
130 B&W (130) Elektra – Composite Lightcurve
39
130 Electra Composite
40
130 Phase Curve
41
Phase brightening
42
ACKNOWLEDGMENTS Stefano Mottola – AstPhot32 photometry software John Saxton – Lymm photometry software Norman Walker – Provision of V and I filters Acknowledgments
43
THANKS FOR YOUR ATTENTION End of talk
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.