Ram Sagar

Aryabhatta Research Institute of Observational Sciences (ARIES)

Nainital, India

4-m class New Technology optical telescopes at Devasthal Observatory, Nainital, India

Outline of the talk Objectives:- Observational facilities (0.35 – 2.5 µm); Geographical (Foothills of central Himalayas in India) importance and Multi-wavelength astronomical observing capabilities

Installed by 2013 360-cm thin mirror active support 400-cm Liquid mirror

Conclusion and summary

Future Major Indian Initiatives in Optical Astronomy

ASTROSAT – Visible, UV and X-ray astronomy The first Indian multi-wavelength astronomy satellite

planned to be launched in 2013 with 5 instruments and a life time of ~5 years.

OPTICAL TELESCOPES4-meter ILMT by 2013 with Belgium, Poland & Canada 3.6-meter to be set up at Devasthal, Nainital by 2013

(Jointly with Belgium)

Participate in 30-meter size telescope and build a 10 meter class optical telescope in India by 2025

~200 km

Alt=2 Km;Long=79º 27´ E;

Lat=29º 22´ N

Alt=4 Km

Geographical location of Devasthal (meaning abode of

God) in the Uttarakhand map (courtesy: ISRO)

Characterization of Devasthal siteSagar et al. (2000) AAS 144, 349-362; Stalin et al. (2001) BASI 29,

39-52 Pant et al. (1999) AAS 136, 19-25

• Identified after an extensive survey during 1980-90.• Meteorological parameters like stability of night time temperature, Relative humidity, Atmospheric pressure, wind speed and cloud coverage.• Differential Image motion monitor (DIMM) for 80 nights in 1998-99 less than 1 " in a stretch for > 4 hr, 2-4 hr & < 2 hr are 10 %, 47 % and 43 % respectively. Mean seeing ~ 1.1 arc sec• Micro-thermal measurements at 2, 8 & 11 meters indicate that seeing could be ~0.8 arc sec above 8 meter from the ground.• Rainfall ~ 2000 mm/year; few days snowfall. Clear nights : ~ 210 /year ~160 photometric• Air temp -4.5 º to 22 º C in a year. Nightly variation ≤ 2 º C.• 3 Km Road provides a state road connectivity to Nainital and other places.• Data connectivity: High speed 2.4 GHz microwave link with 18 Mbps band width.• A 3 phase dedicated feeder of 11 KV; water and Guest House accommodation.

Installed in Oct 2010

Civil work, Dome Design & construction; Electrical installation

done by ARIES

Fork Equatorial Mounting; open truss Five axis (tip, tilt and 3-axis ) — M2

Friction drives for RA and DecControl:- dedicated software; GPS ;

On site weather monitoring; Pointing accuracy ~ 10” RMS.

Photometric observations ofStar clusters, galaxies, monitoringOf extra-solar planet and optical Transients like GRBS and SupernovaeSagar et al. (2011) Current Science,

Vol 101, No.8, Page 1020-1023

130-cm telescope

Crab Nebula – SN remnant Pleiades star cluster

Orion Nebula – Star Forming Region, BVR colour

composite

M82 – Star Burst Galaxy, Hα red colour

Kb=0.24 mag;Kv=0.14 mag;Kr=0.08 magSky brightness (square arc sec)~ 21.2 mag in V Limiting magnitude 24.5 mag in R ~30 min; FWHM < 1.5”

Earth’s atmosphere Scintillation limited low amplitude flux variationsTransiting extra-solar planet WASP-12; V=11.7 mag; 3300 CCD frames of 5 sec each in R; 4.5 hrs observations; Flux variation 17 mmag; Error: < 1 mmag compared to Manora Peak ~ 3-4 mmag

3.6 m NTT (2007-2013) Project Cost ~ 20 M Euro (Belgian Contribution is 2 M Euro => 7 % observing time )

Key players

•The telescope is manufactured by Advanced Mechanical & Optical System (AMOS), Liege in Belgium. # SPIE 2012:-8444—67, 102, 150, 186 and 8451—82 Its Observatory Control system and data archiving are being developed by ARIES.

•The mirror blank was purchased from SCHOTT, Germany. It is 3.7 meter in

diameter & 165 mm in thickness (22:1). It was figured and polished by

Lytkarino Optical Glass Factory (LZOS), Moscow, Russia. # SPIE 2012:- 8450—176•The dome/enclosure is being completed by Pedvak & PPS, India. #SPIE 2012:- 8444--152

•The aluminizing unit was delivered by HHV, India. # SPIE 2012:- 8444-152

•The first back end instruments “Faint Object Spectrograph & Camera” and CCD imager

are being designed, assembled and implemented by ARIES. #SPIE 2012:- 8446-38

Basic Configuration• F/9, Ritchey-Chretian (RC) two mirror Cassegrain focus as an optimization for imaging, spectroscopic and polarimetric observations.

• Science field of view : half degree with Corrector.

• 80% encircled energy is in < 0.45 arc sec diameter.

• Compact (alt-azimuth) and seeing-limited (Active optics) Telescope.

Active optics system

A low-frequency system thatdetects and corrects deformations,aberrations or any other phenomenathat degrade the image quality.

Wave front sensor

M1 support system

M2 hexapod

Telescope control system

The primary mirror

•The thermal expansion of glass (“Zerodur”) is ~ 10-7 - 10-8 /K.

•The mirror is polished to optical accuracies, in 3.6 meter it is ~33 nm rms. •The primary mirror is not aluminized now and first aluminization will be carried out at Devasthal before the installation.

Primary Mirror Active supports

69 axial actuators (active push only) - 7 nm Resolution - 0.2 N accuracy - 10-1000 N range 24 lateral supports (passive static)

Secondary Mirror Hexapod

Six -degrees of freedomTx, Ty, Tz; Rx, Ry, Rz

Focus (Tz) – 1 μm

Centering (Tx,Ty) – 7.5 μm

Tip/Tilt (Rx,Ry) – 1 arcsec

Dec 2011AMOS WorkshopBelgium

Seeing at Factory

When the nights were cold (~8 to 10 C); the seeing was in the range 6”-7”.

When the nights were warm (~12 to 14 C); the seeing was ~3”.

The best seeing recorded is 2.3” in warm nights.

--> It is clear that temperature difference should be minimal to get best seeing.

The optics is not fully aligned here; No attempt was made to align the optics further as WFS was not functional at that moment.

FWHM = 3.3”

FWHM = 2.3”

<--- ~9.6” --->Muscida star (+60.7 dec) : 3.3 mag VNo Filter.

Telescope Enclosure

Diameter – 16.5 mDome height – 29 mDome weight – 170 TonRotation Speed – 7 m/minWind speed – 15 m/s (55 m/s)Ventilation – Pier, air flushing, hot air ducts

Enclosure design has been completedConstruction going on

Dome, Slit and Wind screen M1 ~ 14 meter above ground 25.44 Hz Pier14.26 Hz Pier + Tel

Coating Plant

Completed in December 2011(HHV Bangalore Workshop)

Al deposition 1000±25 Ǻ

R = 92±2 %λ=350-850 nm

1. Faint object spectrograph and Camera & CCD Imager (Design and CDR are completed. ARIES initiative) 0.35—0.9 µm; Field of View = 14´ X 14 ´ (Imag) & 10´X10´ (Spec)

2. NIR spectrograph (TIFR, Mumbai) - design phase, expected completion – 2014 0.5—2.5 µm; Field of View = 7´ X 7 ´

3. High resolution optical spectrograph (HERMES-like) (ARIES : in collaboration with Belgium) - design phase; 0.38—0.9 µm; R = 30 K and 60 K

4. Integral Field Unit (IUCAA, Pune) -design phase

Instruments

4-meter International Liquid Mirror Telescope

Belgium, Canada, Poland and India http://www.aeos.ulg.ac.be/LMT

Liège University, AMOS & CSL (Liège Space Center) & ROB (Royal Observatory of Belgium),

Canada (Laval University, Montreal University, Toronto, University, Yorke University)

ARIES (India)

Expected to be installed by Feb 2013

Poels et al. (2012) IAU Symp 285, page 394-396

Upper End

Structure

Mirror

CCD Camera

Corrector

Alignment mechanisms

Container

BearingMotor3-point mount

04/22/23 22

Detector will work in Time Delay Integration mode

AMOS factory:- Hg thickness 1 mm; surface λ/2

4-m & F/2 + 4K x 4K (15 micron; 0.4 arc-sec/ pix) About 30 arc-sec strip

At latitude +290 30’ a half degree strip => 156 square degree

About 10 GB data/ night

Expected database towards the Galactic bulge direction_______________________________________________________Number Objects Timescale Significance__________________________________________________________________50/yr Microlense 2-1000 d Galactic structure, dark-matter10 Million Stars non-variable Stellar populations, Galactic structure 30000 Variables 0.1-3000 d Stellar variability, population tracers8000 Binaries 0.2-3000 d Stellar evolution, distance estimates8000 LPVs, SPVs 50-1000 d Galactic Evolution, pulsation physics5000 spotted RSCVn 15-200 d Stellar magnetic activity and rotation1400 RR Lyrae 3-28 hr Distance indicators250 Delta Sct 1-6 hr Pulsation physics, stellar structure20 Cepheids 2-40 d Cosmological distance indicators5/yr CVs 1-10 d Accretion physics, nucleo-synthesis_______________________________________________________

Summary and looking forwardThe 3.6 meter telescope is fully operational at the factory and first light images have been obtained.

The optics quality appears excellent under nominal seeing conditions at factory.

The mechanical performance of the system also appears very good as compared to the designed

and modeled performance.

Parts of 4-m ILMT have arrived at the site.

Installation of both telescopes is expected to be completed by Q2 of 2013 and first light and initial tests by end of 2013.

These facilities can be used for Indo-South African collaborations in both instrumentation and scientific projects. Experience of both countries in building major facilities can also be used under the Indo-South African collaborations.

Thanks for your attention!!