The CFHT Legacy Survey
Strategy for the
Detection and Follow up
of Trans-Neptunian Objects
A. Campo Bagatin, G. Bernabeu, P.G. Benavidez
(Universidad de Alicante, Spain)
J.-M. Petit (Observatoire de Besançon, France)
B. Gladman, JJ Kavelaars, L. Allen
(University of British Columbia, Vancouver – Canada)
H. Scholl, P. Rousselot, M. Holman, C. Veillet, T. Grav, P. Nicholson,
N. Murray, M. Duncan, C. Hergenroter, V. Carruba, ...
Why ever look for
and secure TNOs?
• What caused the dynamical excitation
of the Edgeworth-Kuiper belt?
• Can objects form in the region beyond
50 AU?
• What is the size distribution of
material?
• What is the largest member of the
belt?
How well known is
the population of TNOs?
• 1992: discovery of the first TNO
1992QB1
How well known is
the population of TNOs?
• 1992: discovery of the first TNO
• Situation at the end of the ’90s
How well known is
the population of TNOs?
• 1992: discovery of the first TNO
• Situation at the end of the ’90s
• Present situation
How well known is
the population of TNOs?
• 1992: discovery of the first TNO
• Situation at the end of the ’90s
• Present situation
• How to improve our knowlwdge?
Necessity for a true bias-free survey
The Canadian-France-Hawaii
Telescope (CFHT)
Legacy Survey
Goals: Detection of ~2000 SN/ Galactic stars/
Discovery of TNOs/ Galaxies distribution/
Telescope: CFH 3.6 m telescope (CFHT)
at Mauna Kea (Hawaii, U.S.A.)
The Canadian-France-Hawaii
Telescope (CFHT)
Legacy Survey
Goals: Detection of ~2000 SN/ Galactic stars/
Discovery of TNOs/ Galaxies distribution/
Telescope: CFH 3.6 m telescope (CFHT)
at Mauna Kea (Hawaii, U.S.A.)
Detector: MegaCam (2048 x 4612 pxl = 1º x 1º)
36 chip mosaic camera.
The Canadian-France-Hawaii
Telescope (CFHT)
Legacy Survey
Goals: Detection of ~2000 SN/ Galactic stars/
Discovery of TNOs/ Galaxies distribution/
Telescope: CFH 3.6 m telescope (CFHT)
at Mauna Kea (Hawaii, U.S.A.)
Detector: MegaCam (2048 x 4612 pxl = 1º x 1º)
36 chip mosaic camera.
5 years ecliptic survey within 30º from the ecliptic
(450 dark/grey nights over 5 years: 2003-2008)
http://www.cfht.hawaii.edu/Science/CFHTLS/
The CFHT-LS STRATEGY
1. Discovery: Triple on a 20-sq.deg. sky
patch at opposition (within 15º from the
ecliptic). (Mainly at CFHT).
Triple: 3 exposures of the same FOV,
at ~1 hour intervals
(Rate of motion: 2.5-3”/hour)
Images processed by an automated
moving object detection package:
TNO candidate images are then processed
by human eye.
The CFHT-LS STRATEGY
1. Discovery: Triple on a 20-sq.deg. sky
patch at opposition (within 15º from the
ecliptic). (Mainly at CFHT)
2. Nailing: One image of the same patch
within 24-72 hr. (Mainly at CFHT)
t1
t2
Discovery sequence
t3
t4:
Nailing
The CFHT-LS STRATEGY
1. Discovery: Triple on a 20-sq.deg. sky
patch at opposition (within 15º from the
ecliptic). (Mainly at CFHT)
2. Nailing: One image of the same patch
within 24-72 hr. (Mainly at CFHT)
3. Check-up: Another triple on the original
patch 2 months later. (CFHT, Palomar, VLT,
Calar Alto, NOT, KPNO, MMT, ESO 3.6, VLT)
Discovery sequence prediction
First night prediction
t5: Check-up
2-3 months after discovery
The CFHT-LS STRATEGY
1. Discovery: Triple on a 20-sq.deg. sky
patch at opposition (within 15º from the
ecliptic).
2. Nailing: One image of the same patch
within 24-72 hr.
3. Check-up: Another triple on the original
patch 2 months later. (CFHT, Palomar, NOT,
Calar Alto, KPNO, MMT, ESO 3.6, VLT)
4a. Repeat: 1+2 years after discovery, at other
facilities (3 years after discovery, if at CFHT),
following the object predicted motion.
4b. Reapeat Nail: One image of the same patch
within 24-72 hr.
4c. Reapeat check-up: Another triple on the same patch
2 months later.
Check Up prediction
Discovery sequence prediction
t6: Next opposition
RELIABLE TRACK
Achievements
Pre-LS:
Discovery (and track) of ~1/3 of the known
TNOs.
Identification of the “Extended Scattered Disk”.
After 1 year of LS (mid 2003-mid 2004):
95 objects discovered.
All objects with 2-months arc, have been
recovered at second opposition.
The CFHT Legacy Survey
Strategy for the
Detection and Follow up
of Trans-Neptunian Objects
A. Campo Bagatin, G. Bernabeu, P.G. Benavidez
(Universidad de Alicante, Spain)
J.-M. Petit (Observatoire de Besançon, France)
B. Gladman, JJ Kavelaars, L. Allen
(University of British Columbia, Vancouver – Canada)
H. Scholl, P. Rousselot, M. Holman, C. Veillet, T. Grav, P. Nicholson,
N. Murray, M. Duncan, C. Hergenroter, V. Carruba, ...
TRANS-NEPTUNIAN OBJECTS
Ixion