The FMOS Facility for the SUBARU telescope

The FMOS Facility for the SUBARU telescope

Gavin Dalton

Oxford/RAL

Overview of Fibre Multi Object Spectrograph project for the Subaru telescope

Masayuki Akiyama

(Subaru Telescope, NAOJ)

on behalf of FMOS team (P.I. Toshinori Maihara)

FMOS: instrument overview

FMOS: project overview

FMOS: prime-focus corrector

• Prime-focus corrector designed and fabricated by AAO

• Three BSM51Y design with F/2.0 and 30arcmin diameter FoV.

• Image quality optimized between 0.9-1.8micron

• If we put 400 magnetic buttons with fibres (like 2dF) on the prime-focus of the Subaru telescope, it would be like,,,

• So we need new fibre positioning method for FMOS…

FMOS: fibre positioner

145mm

= 30arcmin

FMOS:Echidna: 1998 Birth of Echidna concept

• Concept by Peter Gillingham (AAO) shown at SPIE@Kona

• Tiling the focal plane with 400 of them = 7mm x 7mm each

FMOS:Echidna:Long-term development effort

• 1998 Echidna with “Nano-motor”

• 2000 Echidna with “ball-spine” design

• 1999 Echidna with “inch-worm” design

FMOS:Echidna: 2001 Final design fixed

“Stick-and-slip” motion with sawtooth voltage signal

FMOS:Echidna: Under testing in Hilo

• Focal plane with 480 fibres.


• Focal plane imager.


• Positioner unit

• SEE ECHIDNA THE MOVIE !!

Movies

FMOS:Echidna: test results so far

• Focal plane imaging camera tested. Positions of 400 fibres in 154mm FoV can be measured with 2-3micron r.m.s. accuracy.

• Configuration accuracy of 10micron (corresponds to 0.12 arcsec. Fibre core is 100micron, i.e. 1.2”) can be achieved for >95% of the 400 fibres with 7 iterations in 11minutes.

• Fibre tip is 30micron r.m.s. from the focal plane.

FMOS: prime-focus unit (PIR)

• New prime focus unit with • instrument focusing unit (Z-movement)• corrector lens adjustment mechanism (XY-movement)• cable wrapping unit

for FMOS is constructed by Kyoto Univ. and Mitsubishi.

FMOS:PIR+Echidna under testing NOW

FMOS: fibre train with connector

• Fibre trains with• 120mm 200 fibres/slit• strain relief boxes• F2/F5 conversion air connector• fibre back illumination system

was designed and fabricated in Durham.

• F2-side fibre

• F5-side fibre


FROM ECHIDNA

Launch lens

LED on PCB

TO SPECTROGRAPH

Sub-connector Blocks

Receiver Lens

Removable Ferrule

Fixed Ferrule

Insertable Coupling Prisms

LED Coupling Lens

N.B. some of the tolerances on these lenses turn out to be difficult!

Mapping direction

24 furcation tubes carry 480 fibres (20 in each)

from F P to connector (Launch side.) Each head

consists of 6 sub -con nectors, 2 tubes feed each. T he elem ents are arranged in dual colum ns of

20. Cabling length: 7.6 m .

Rows of circles represent the entire spine array (m inus fiducals and guide fibres.)

Packing is hexagonal.

R/ G/ B → Telescope fiel d of vi ew (2 00 spines) seen by spectrograph I

T /Y / M → Telescope fiel d of view (2 00 spines) seen by spectrograph II No co lour → Redundant area outside field (80 spines) Numbers at left show active fibres present in each row.

The l enslet -coupled fibres are removable, so elements on this side are interchangeable (purple.)

Populated elements in the receiver -side correspond to the 400 spines within the telescope field ONLY (CO L O U R circles.) Redundant s pines ( No colour in ECHIDN A field) are not coupled to the spectrogr aph. The contiguous mapping is conserved .

24 furcation tubes carry 400 fibre s (7, 11, 13, 15 etc.) Length: 7 m (approx.)

20 co nduits continue, carrying 400 fibres (20 each) through into the Nasmyth strain relief box, & then on, into the spectrograph slit units. Length: 40 m& 3 m (approx.)

ECHIDNA – Focal plane

Connector heads (Launch side)

Conne ctor heads (Receiver side)

Nasmyth strain relief

unit s

Slit unit (20 output blocks , 10 in each slit, (20 fibres per

block )

7 11 13 15 17 18 19 20 20 20 20 20 20 20 20 20 20 19 18 17 15 13 11 7

Top end strain relief

unit s

How to map ECHIDNA to spectrographs?


A lot of attention has been paid to cable management!

The FMOS Spectrographs

Gavin Dalton

Oxford/RAL

• 2 bench-mounted spectrographs (total slit length is ~700 arcseconds).

• Optics cooled to ~200K, with articulated cryogenic cameras

• OH suppression by masking lines at intermediate focus.

• Full ZYJH wavelength coverage in 4 shots at suppression resolution

• Full coverage in 1 shot through redispersing VPH grating

Spectrograph outline

Can work between the lines, but then we start to run out of pixels to do anything useful with this wonderful wide field!

Because the IR sky is rather nasty…

Why OH Suppression?

Accomodation Issues

•No space for systems of this size in any convenient location

•Extra floor added to Subaru enclosure on IR side above the Nasmyth platform

•Limited access (spectrogaphs must be assembled in situ)

•Cost…

Spectrograph Design

Mask Mirror M2H & M2J

Collimator M1

Fold Mirror

Reflection GratingG1 (used in+1 order) Corrector Plate

S1

Corrector Plate S2

VPH Grating G2 (used in+1 order)

300mm Dewar Window

Camera System

Hawaii-II Detector Y

X

Z

Predicted performance

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.8 1.3 1.8

Throughput to FocalPlane

Fibre System

FMOS Spectrograph

Camera Throughput

Total SpectrographThroughput

Detector QE

Total SystemThroughput

Low Res SystemThroughput

Installation (two weeks ago)



FMOS Commissioning Schedule

Near future mile-stones 　 (first discussions on this project were 01/97!)

• 2007/10 Transfer IR prime-focus unit (PIR) and Echidna fibre positioner to summit

• 2007/12 Engineering observations of IR prime-focus unit•Check image quality•Check Auto-Guiding/Shack Hartmann system

• 2008/01 Engineering observation of Echidna fibre positioner•Check positioning accuracy (spectrographs available)

• 2008/02 Start engineering observation with two spectrographs

• 2008/?? Open use observation with shared risk mode/GTO

So what can we do?

• 20 nights GTO: Galaxy evolution survey, ~15000 ‘good’ spectra from e.g. UDS (Interesting possibility would be to cover the DEEP2 AEGIS area?).

• Opportunity for a large programme (few x 105 redshifts). –See Totani’s talk.

• Whatever else comes up?

Documents

The FMOS Facility for the SUBARU telescope