Gemini

• Overview of the telescopes

• Gemini’s core science goals

• Gemini instrumentation

• Applying for Gemini time

2001 Observational Techniques Workshop

Warrick Couch, UNSW

Gemini

North

Gemini

South

Overview of the telescopes(total capital cost = US$187M)

Gem-N Gem-SPrimary mirror:

•8.1m diameter

•20cm thick

•mass = 22.2 tonnes

•coated for UV/IR performance

Primary mirror supported by air pressure + 180 actuators which maintain shape to better than a micron.

Secondary mirror (f/16):

• 1.0m diameter

• Mass 45kg

• Fast tip-tilt at up to 200Hz

Cassegrain Focus: Instrument Support Structure + A&G

Core Science Goals

• Circumstellar disks and planetary systems

• Formation of the elements

• Formation and evolution of galaxies

• Star formation

• Stellar interiors structure

Circumstellar disks and possible planetary systems

The nature of the particle disks discovered around stars like -Pic detailed mapping to understand the process of planet formation.

• Map at 10m and beyond, where Gemini should deliver a resolution of better than 0.3 arcsec, corresponding to 1-2AU for the nearest examples.

• Gemini’s competitive edge: diffraction-limited imaging and low thermal emissivity.

Formation of the elements

Determination of the chemical enrichment history of the Galaxy and the Universe via high resolution spectroscopy of the oldest stars in the Milky Way and gas clouds illuminated by distant quasars.

• High-resolution (R=50-150,000) spectroscopy of faint objects at uv-optical wavelengths

This science program severely compromised with the cancellation of HROS, and its replacement with HRBS which, being fibre-fed, will be unable to observe at 3800Å.

Formation and evolution of galaxies

Determine the morphology, content, and composition of nascent and adolescent galaxies in the early universe. Do this at optical wavelengths, to reveal the properties of the youngest stars in such systems, through to the thermal infrared where dust re-radiates the emission at shorter wavelengths.

•Imaging and multi-object spectroscopy at optical and infrared wavelengths, with high spatial resolution.

Star formation

Address the age-old question of how stars

form and what conditions lead to

proto-stellar collapse. In particular, study the

role of outflows in the star formation process

• Near infrared imaging and spectroscopy at the highest possible spatial resolution

• Gemini advantage: diffraction-limited performance (or near to) in the near-infrared.

Stellar structure

Determination of the internal structure of stars through the study of the small and complex oscillations that take place at their visible surface.

• Very high resolution optical spectroscopy and continual monitoring for many hours.

Performance: it’s not just (aperture) size that

counts!

* For 8m, dl~0.02” in V, 0.07” in K, requiring wavefront correction using Adaptive Optics (only practical in IR)

If sky- or detector-noise limited, then speed of observation (1/t) is proportional to:

(D/)2

where D = aperture size and = image size.

is usually dominated by seeing, with seeing-0.2 20% reduction V K.

If can achieve diffraction-limited performance*, then dl1/D (Rayleigh) and speed proportional to:

D4 [factor of 16 in going from 4m to 8m telescope!!]

Seeing Constraints

2001B Instrument Availability

NIRIGMOSHokupa’a/QUIRC

FLAMINGOS-1OSCIRAcquisition

Camera

Mauna Kea Cerro Pachon

2002A Instrument Availability

NIRIGMOSMICHELLEHokupa’aCIRPASS

T-ReCSPHOENIX

Mauna Kea Cerro Pachon

2002B Instrument Availability

NIRIGMOSMICHELLEALTAIR (NGS)CIRPASS

T-ReCSGMOSFLAMINGOS-1PHOENIX

Mauna Kea Cerro Pachon

2004B Instrument Availability

NIRI (NIR)

GMOS (Opt)

NIFS (NIR)

OSCIR (MIR)

ALTAIR+(LGS/AO)

T-ReCS (MIR)

GMOS (Opt)

GNIRS (NIR)

NICI (NIR)

HRBS (Opt)

FLAMINGOS-2 (NIR)

MCAO (LGS/AO)

Mauna Kea Cerro Pachon

Hokupa’a/QUIRC

Hokupa’a 36 element curvature wavefront sensor and bimorph mirror which uses natural guide stars.

QUIRC 1 – 2.5 m near-IR camera which is fed by Hokupa’a. 1024x1024 HgCdTe array; pixel size = 20 mas 20.2 arcsec FoV!

Performance: near diffraction-limited (d-l) resolution in H & K; FWHM = 2x d-l in J.

The rub: must have a bright point-source within 30arcsec of target!

UH-88”, Courtesy W.Brandner, 0.65” seeing

Filters:

•H•K’ •CO•CO cont.

4’

IRS7 SgrA*

>10 stars per arcsec2 at K~18

Bow shock

Very high extinction clouds

40”

5”

>220 stars in 5”x5”

IRS8 (bow shock)

Public SV Data: M32

Used core of this nearby elliptical galaxy as WFS reference

K’ 480s 0.13” FWHM

0.5 arcsec

Public SV Data: M15

Measured PSF variation over field and H/Q stability and repeatibility on this globular cluster 2 datasets

released K’ 18 x 30s 0.12” FWHM

20 arcsec

Example QS Data

Elliptical galaxy at 150Mpc

FWHM 65 milli-arcsec

IR surface brightness fluctuations

(GN-2000QS-Q-9)

Example QS Data: Galaxies

in Abell 665

Colour composite of Abell 665 (z=0.18)

K’ (28min) J (20 min) HST-I (80 min)

0.2 arcsec FWHM

(GN-2000QS-Q-29)

NIRI – Near Infrared Imager

Detector: 1024x1024 Aladdin InSb arrayImaging:

‘wide-field’ (2’x2’) f/6 mode ( J – L bands) ‘low-bg’ (0.9’x0.9’) f/14 mode ( J, H, K ) ‘high-bg’ (0.9’x0.9’) f/14 mode ( L & M )

Spectroscopy: Long-slit + grism ( 1 – 5.5 microns)

[ R of up to ~1700 (in H) with 0.23” slit ]

Wavefront correction: Active optics (aO) only, with IR on-instrument

wavefront sensor available except in f/6 mode f/32 camera will be fed by ALTAIR (laser g/s)

NIRI Filters available for NIRI Filters available for 2001B2001B

JJHHK, Kshort, KK, Kshort, K´́LL´́MM´́Order sorting Order sorting

filters:filters: J, H, K, L, MJ, H, K, L, M

[Fe II][Fe II]H-continuumH-continuumHH22 1-0 S(1) 1-0 S(1)Br GammaBr GammaK-continuum (2)K-continuum (2)PK50 long-wave PK50 long-wave

blockerblocker

Integration Time Calculator (ITC) available

GMOS – Gemini Multi-Object Spectrograph

Optical spectrograph/imager with a 5.5’ field of view [duplicated for both telescopes]

Spectroscopic modes: standard ‘long-slit’

‘multi-object’ using aperture mask with multiple slits [ up to several hundred in 5.5’ FoV]

Integral Field Unit (IFU) covering 50 arcsec2 with 0.2” sampling

Spectral resolution: R = 670 – 4400 (0.5” slit)

ITC available

FLAMINGOS-1

World’s first fully cryogenic multi-object near-IR ( J, H, K ) spectrograph/imager.

Field of view = 2.7 arcmin (f/16 + 2048x2048 Rockwell HgCdTe array).

‘Long-slit’ and ‘multi-slit’ modes

Spectral resolution: R = 300 (low!) [grisms giving R~2400 planned].

OSCIRMid-infrared (8-25m)

imager and low/medium resolution (R=100-1000) spectrograph.

Uses a 128x128 SiAs detector.

Field of view = 11 arcsec!

Range of broad/narrow filters available centred on: 7.9, 8.8, 9.8, 10.3, 11.7, 12.5, 18, 20.8 m + N-band (10.8 m)

Uses chopping secondary capability of Gemini telescopes.

Acquisition Camera

Optical CCD camera, which can provide U,B,V,R,I imaging over a 2’x2’ field.

Offered in 2001B to develop `quick response’ mode of operation (e.g. for SN and gamma-ray burst follow-up).

ITC available

Applying for time on Gemini – it’s the PITs!

• Proposals to use Australia’s share of time on Gemini are considered by ATAC; semester deadlines are:

March 31st (for ‘B’ semester, Aug-Jan)

Sep 30th (for ‘A’ semester, Feb-July)

• If you collaborate with people from other partner countries, then time can be sought from their TACs as well.

Applying for time on Gemini – it’s the PITs!

•Gemini proposals are assembled and submitted using the Phase-I Tool (PIT), a supposedly user-friendly ‘GUI’-styled program* which solicits:

all the usual info: title, abstract, instrument/mode required, nights (D,G,B), list of targets, guide stars, etc

PLUS attached 3-page postscript file containing scientific justification (and figures) for ATAC

•Once complete, hit the “SUBMIT” button in PIT; it then verifies your proposal and (if OK) sends it to the AAO for official submission. *that should be generally available at your institute; ask your

system manager!

Applying for time on Gemini – extra requirements

•Guide stars: these need to be selected and listed along with each

target object: at a minimum, 1 is required for the peripheral wave front sensor (PWFS), with additional guide stars required if instrument has an On-Instrument Wave Front Sensor (OIWFS), and/or observations involve AO.

The PIT makes the selection process simple through internet links to a guide-star catalog (USNO) and digital sky survey.

Applying for time on Gemini – extra requirements

•“Classical” or “Queue” time (where there’s a choice)?

Classical time is the traditional type of allocation where your nights are scheduled and you travel to the telescope (minimum allocation = 0.5 nights).

Queue scheduled time is where your observations are executed by Gemini Observatory staff at a time when the conditions best suit your program. In this case you have to be much more specific about the observing conditions: seeing, cloud cover, water vapour content, sky and telescope background, air mass.

(minimum allocation = 1 hour).

Key web addresses

www.gemini.anu.edu.au (Australian mirror of the main Gemini web site – with all the information on the telescopes/instruments)

www.ausgo.unsw.edu.au (Australian Gemini Office web site – with all the information relevant to Australian users)

www.aao.gov.au/local/www/sll/applications/ATAC-applications.html (information on applying for time through ATAC)