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Detection and study of supernovae with the 4m
International Liquid Mirror Telescope
BRAJESH KUMAR
University of Liège, Belgium
ARIES, Nainital, India
OUTLINE:
 HISTORY
 BASIC CONCEPTS OF LMTs
 ILMT
Introduction
Science with ILMT
 SUPERNOVAE STUDY WITH ILMT
 CONCLUSIONS
History of Liquid Mirrors
 First concept - Ernesto Capocci - 1850
 First working laboratory LMT- 0.35 m
Henry Skey- 1872
Dunedin Observatory, New Zealand
 Robert Wood – 1909
John Hopkins University
 Ermanno Borra & Paul Hickson- 1982
Laval University, Canada
University of British Columbia, Canada
Basic concepts of Liquid Mirrors:
y
x

Ac
x
Ac
g
Ac
A
A
A
g
Ac
g
Ac
A
g
Ac
A
g
A
g
Basic Concepts of Liquid Mirrors:

Parabola : ideal optical system

Constant gravity (g) + Centrifugal Acceleration (w²x)
 Parabolic surface
Why ?  Surface  Acceleration
dy
wx
 tan  
dx
g
2

w 2 x2 x2
y

2g 4 f
f  ( 2w 2 )
g
Basic concepts of Liquid Mirrors:
 Liquids as mirror:
Mercury, Gallium, Rubidium, Cesium
 Mercury:
It is liquid above -38.8˚C
0
0
Reflectivity : 79% - 90% (3100A
– 13000 A
)
Inexpensive
Surface oxide layer prevents toxic mercury vapors
Basic concepts of Liquid Mirrors
Detector : CCD camera
Time Delay Integration for zenithal telescopes:
• Tracking by electronically stepping the charges on the CCD
• Rate of transfer of charges between rows of CCD equal to sidereal rate
INTERNATIONAL LIQUID MIRROR TELECOPE
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Mirror diameter: 4m
Rotation period: 8 sec
Focal length: 8m – f/2
Resolution: 0.6’’
FOV: 24’x24’
CCD: 4096x4096 pixels (15 mm pixels)
Filters: i’ , r’ , g’ (i’ permanently mounted)
(i’=762.5 nm, r’=623.1 nm, g’=477 nm)
 Working temperature: -20˚C to 25˚C
 Life expectancy: 5 years
(Surdej et al. 2006)
Upper end
CCD Camera
Corrector
Alignment
mechanisms
Structure
Container
Bearing
Mirror
Motor
3-point mount
9
DIFFERENT PARTS OF ILMT
Carbon fiber container (d=4m)
Vertical fixed structure
focal length = 8 m
Air bearing and motor
SPIN CASTING OF ILMT:
Mixing of polyurethane
Pouring of polyurethane
Taking parabolic shape
Final mirror shape
INTERNATIONAL LIQUID MIRROR TELESCOPE
 Collaborating countries: Belgium, Canada, India
 Location : Devsthal, India
79⁰ 41’ East, 29⁰ 23’ N
 Altitude : ~ 2400 m
 Expected first light: September 2010
Devsthal
Nainital
SCIENCE WITH ILMT
 Supernovae
 Variable objects
 Gravitational lenses
 Study of galaxies
 Data base for follow up
SUPERNOVAE STUDY WITH ILMT
SNe search and related problems
 Local SNe are rare
 Sample of galaxies
 Frequency and magnitude of observations
 Instruments/techniques
The answer is ILMT
SUPERNOVAE STUDY WITH ILMT
ILMT:
sky strip=24ˊ
galactic latitude~ 30˚
total observed area=146 sq.
deg.
extragalactic region=72 sq.
deg.
Integration time single pass
t=1.37 *102 *n w/f cos(lat)
n=number of pixels
w= width of pixel
f= focal length
lat=latitude of the observatory
ILMT integration time ~ 100 seconds
Limiting magnitude (100 seconds)=22.5
Co-addition will increase the limiting magnitude
SUPERNOVAE STUDY WITH ILMT
Supernovae detection : (0.3<z<0.5)
Type Ia
1000
Core collapse 3600
SNe Ib/c
1080
Bright SN Ib/c 216
(Pain et al. 1996, Dahlen et al. 2004 ,
Cappellaro et al. 1999, Strogler et al. 2004)
O-IR telescopes, additional benefit
 For any transient event recognized by ILMT, the 3.6m
telescope will be used for further photometric and
spectroscopic studies.
CONCLUSIONS
 ILMT will scan 24’x24’ of sky and detect many stellar objects.
 It will provide unique data base for large conventional
telescopes.
 Thousands of supernovae will be detected ( both type Ia and
core collapse) using ILMT.
 More light on classification of Supernovae.
 About GRB supernovae relation
THANKS
http://www.aeos.ulg.ac.be/LMT