Large field of view and ELTs: an impossible marriage?

Conference “Feeding the Giants: ELTs in the era of Surveys” -- Ischia 31/08/2011

Large field of view and ELTs: an impossible marriage?

Paolo Ciliegi (INAF -OABO) on behalf of the MAORY team

Multi conjugate Adaptive Optics RelaY for the E-ELT

INAF (OA-Bologna, OA-Padova, IASF-Bologna, OA-Arcetri)

Università di Bologna

Office National d’Etudes et des Recherches Aerospatiales

European Organisation for Astronomical Research in the Southern Emisphere

Tomelleri s.r.l.

www.bo.astro.it/maory

Conference “Feeding the Giants: ELTs in the era of Surveys” -- Ischia 31/08/2011

OUTLINE

•MAORY OVERVIEW : the multi conjugate adaptive optics module for ELT

• THE LARGEST POSSIBLE FIELD OF VIEW @ ELT from GLAO to DIFFRACTION LIMIT

• SYNERGIES BETWEEN SURVEY FACILITIES AND ELT.

Conference “Feeding the Giants: ELTs in the era of Surveys” -- Ischia 31/08/2011 3

What is MAORY? Multi conjugate Adaptive Optics RelaY for the E-ELT

Corrected field of view– Central unvignetted 53"x53" – Maximum requested field Ø=120"– Technical field Ø=160" for Natural Guide Star search

Wavefront sensing– 6 Sodium LGS WFS

LGS projected from M1 edge– 3 NGS WFS

Wavefront correction– Telescope M4 + M5– 2 post-focal deformable mirrors (4km, 12.7km)

Output ports for science instruments– Gravity invariant with mechanical derotation for MICADO– Lateral port for detached instrument (no mechanical derotation)


What is MAORY?

Client instruments– MICADO

• High angular resolution camera (and slit spectrograph)

• Precision astrometry and photometry

• Required AO correction: uniform with high sky coverage

• Wavelength range 0.8-2.4µm. Field of view: 53"53"

• MAORY thermal background < 50% (telescope + sky) @Ks

– SIMPLE• High spectral resolution IR spectrograph

• Required AO correction: on-axis with high sky coverage

– Others


Overall layoutPre-focal station

Nasmyth platformMAORY

MICADOGravity invariant port

Lateral portArea for detached instrument


Post-focal relay


Performance – Strehl Ratio

Ks 2.16µm

H 1.65µm

J 1.215µm

I 0.9µm

Seeing 0.8 arcsecSeeing 0.6 arcsec

MAORY vs. ATLASATLAS performance courtesy of T. Fusco


Performance – Sky coverage

Although we have 6 LGS projected from M1 edge, we still need Natural Guide Stars (NGS) for

Tip Tilt correction

Sodium layer effects


Sky coverage…. where to search NGS

MICADO

53”MAX FOV 160arcsec

20”

NGS WFS


Sky coverage evaluated at North Galactic Pole Reference conditions: Seeing 0.8", L0 = 25m

Random star counts generated by TRILEGAL code 3-NGS asterisms formed for each trial down to H ~ 21 “Best” asterism chosen. Figure of merit for each NGS asterism

– Measurement noise

– Temporal error

– Anisoplanatic errors (NGS positions and uneven brightness)

Each star is assigned the Strehl Ratio value corresponding to its position in the NGS seach field Ø = 160"

Strehl Ratio comes from MCAO correction (1.5-1.8µm)




Minimum field-averaged Strehl RatioScience field 53"53" (MICADO)

Sky Coverage

Ks H J I

0.53 0.34 0.14 0.03 39%

0.51 0.32 0.13 0.03 50%

0.49 0.30 0.11 0.02 60%

0.47 0.27 0.09 <0.01 70%

0.41 0.22 0.06 <0.01 80%


THE LARGEST POSSIBLE FIELD OF VIEW @ ELT

LARGE FIELD OF VIEW AND ELT : AN IMPOSSIBLE MARRIAGE ?



The actual imaging camera designed for E-ELT is MICADO characterized by superb capabilities in terms of

sensitivity (K ~ 30 mag AB, 5 sigma , 1-2 ours)

resolution (3 mas pix scale)

and astrometric precision.




The actual imaging camera designed for E-ELT is MICADO characterized by superb capabilities in terms of

sensitivity (K ~ 30 mag AB, 5 sigma , 1-2 ours)

resolution (3 mas pix scale)

and astrometric precision.

The Micado Field of view is 53 x 53 arcsec.



MICADO 53’’x53’’

53 x 53 arcsec field with a spatial resolution at the diffraction limit

level and a 3 mas pixels size is an impressive, huge field of view

that will open new frontiers in may astronomical fields

(see Greggio and Fiorentino talks)


MICADO 53’’x53’’

53 x 53 arcsec field with a spatial resolution at the diffraction limit

level and a 3 mas pixels size is an impressive, huge field of view

that will open new frontiers in may astronomical fields

….but of course is not a survey facility….


WFI ESO 2.2m 2040’’ x 2040’’ (34’ x 34’)

MICADO 53 x 53 arcsec

2 MASS 8.5’ x 8.5’

ACS HST

202’’x202’’

WIRCAM CFHT near infrared 0.3’’/pixel

20’ x 20’


Large deep imaging surveys have formed the backbone of extra-galactic survey for the last 15-20 years and there is no reason to expect this to change dramatically in the coming years.

LSST VISTA VST SASIR

Can we image a Wide Field Imager for ELT that can play a direct role as survey facility?

Network Program “ Wide Field Imaging at the E-ELT : from GLAO to diffraction limit”

PI . M. Arnaboldi (ESO) (E-TRE-ESO-508-0755)

WFI at the ELT


We investigate the possibility for a Wide Field Imager exploiting the full MCAO corrected field

MICADO

53”MAX FOV 160arcsec

NGS WFS

90 x 90 arcsec

Pixel scale : 8-10mas

Balance between

NGS search field

Number of detectors


ELT and Large Field of view

Maximum field of view at a resolution slightly worse than diffraction limit (8-10 mas pixel scale) is about 90 x 90 arcsec.

We can reach bigger field of view (tens of squared arcmin, 5’x5’) but we must accept moderate resolution at the level of the GLAO correction.

These numbers confirm the difficulty of the giant telescopes to work alone as survey facilities, highlighting the absolute need for synergies among different facilities.


SYNERGY --- MAORY and NEAR INFRARED SURVEY

Which is the fundamental “food” for MAORY ?


SYNERGY --- MAORY and NEAR INFRARED SURVEY

In our sky coverage calculation, we simulated the availability of a deep (down to H=21) infrared catalogue

For real observations we need real deep catalogues with:

Reliable stars/galaxies separation.

Accurate position (NGS probe have a FoV of 3’’)

These catalogue must be already available at the time of the proposal in order to check the NGS asterism.

Deep near infrared catalogues will be a fundamental input that forthcoming survey facilities like VISTA and SASIR must provide to ELT.

Which is the fundamental “food” for MAORY ?


CONCLUSIONTHE COUPLED MAORY + MICADO IS A FANTASTIC TOOL IN TERMS OF STREHL RATIO, EE, SENSIBILITY RESOLUTION AND ASTROMETRIC PRECISION

…HOWEVER WITH A FOV OF 53 X 53 arcsec is not an instrument for surveys


CONCLUSIONTHE COUPLED MAORY + MICADO IS A FANTASTIC TOOL IN TERMS OF STREHL RATIO, EE, SENSIBILITY RESOLUTION AND ASTROMETRIC PRECISION


We investigate the possibility for a Wide Filed imager @ ELT.

At resolution slightly worse than diffraction limit the maximum FoV is ~ 90 x 90 arcsec, while at GLAO resolution is 5 x 5 arcmin.

…. So Large Field of views and ELT seems to be an impossible marriage !!!


CONCLUSION

…. This impossible marriage implies that the synergies between survey facilities and giant telescopes are fundamental.

As an example we show that large (possible all sky) deep (H~ 21) near infrared catalogues are a fundamental input that forthcoming survey facilities must provide to ELT

THE COUPLED MAORY + MICADO IS A FANTASTIC TOOL IN TERMS OF STREHL RATIO, EE, SENSIBILITY RESOLUTION AND ASTROMETRIC PRECISION


We investigate the possibility for a Wide Filed imager @ ELT.

At resolution slightly worse than diffraction limit the maximum FoV is ~ 90 x 90 arcsec, while at GLAO resolution is 5 x 5 arcmin.

…. So Large Field of views and ELT seems to be an impossible marriage !!!

Large field of view and ELTs: an impossible marriage?

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