Astronomy 302

Lecture 18

Steward Large Telescopes

1.0 LARGE OPTICAL/IR TELESCOPES AT STEWARD

There are many other telescopes in world besides the 61inch

1.1 The MMT

The most important Steward Telescope is currently the MMT

The 6.5m MMT is 50% owned by Steward/Arizona (with Harvard/CfA)
Its site at the peak of Mt Hokpins leads to good seeing ~0.6-0.7" and easy access from Tucson (2 hours by car). Unfortunately that also leads to some light pollution at night in the visible.

MMT by Mark Ordway

The MMT has an f/15 adaptive secondary for AO work
                  unique in world 5-20 um AO imaging 0.05" imaging at 1 um
                          uses ARIES (1-5 um imager/spectrograph)
                                  CLIO (3-5 um imager)
                                  and MIRAC4 (5-25 um imager)

an f/9 for optical long slit spectra and polarimetry
an f/5 for wide field (1 degree) imaging (Megacam) and multi-object spectra (Hetospec)

Some of the MMT's unique instruments:

The world's only adaptive secondary (unique mid IR AO science)

Hectospec allows 300 spectra of closely spaced objects to be obtained at once over ~60 arcminutes with the f/5 secondary see here for a movie

1.2 The LBT

The LBT is two 8.4m mirrors on the same mount. The LBT is the biggest telescope in the world. The LBT HQ is based at Steward. The scope is located at Mt Graham which is very high 10,700', very dark, and very dry. Steward has 25% of LBT.

It is really really big!

And it has currently wide field Blue and Red prime focus cameras.

Sometime past summer 2009, the LBT should have AO secondaries (like the MMT) and that will allow beams from both primaries to be combined. That should give ~0.01" images at 1 um. And allow one to "null" out the light from bright stars to
detect faint objects.

1.3 The SMT

Steward's main sub mm telescope is the SMT (or HHSMT),
which is a 10m dish for sub mm astronomy. In the sub mm one can detect rotational lines from molecules. Hence disks of CO gas can be imaged around young stars for example.

1.4 The Twin 6.5m Magellan Telescopes

Steward's main southern hemisphere telescopes are the twin 6.5m Magellan telescopes. The two telescopes are located 60 meters apart on an isolated peak (Cerro Manqui) at the Las Campanas Observatory in Chile. The site is very dark and has very good ~0.6" seeing.

A unique instrument at Magellan is the very wide (30') IMACS MOS
It is the most powerful wide field MOS operational today.

IMACS as a Camera (30' FOV)

240 0.8" wide slits made these spectra (of cluster RCS2347.3-3634 at z~0.5)

2.0 PUBLIC OPTICAL/IR TELESCOPES

45% of the twin 8m Gemini telescopes are for the astronomy community (paid
by the NSF)

GEMINI NORTH

Gemini North on Mauna Kea, 8m

Gemini North has nice suite of instruments optimized for the
optical & IR, it has excellent ~0.5" seeing and is very dry and dark.

Instruments:

GMOS-North is a large MOS and CCD (used when Moon is down)
NIRI is a 1x1k 1-5 um camera
NIFS is an 1-2.5 um IFU (a camera where each pixel gives a spectrum)
Altair is an AO system the feeds NIFS & NIRI it now has a Laser Guide star too.
Michelle is an 5-25 um imager and spectrograph

GEMINI SOUTH

Gemini south is identical to Gemini North but located in Chile,
The site has good ~0.6-0.7" seeing and is dark.

Instruments:

GMOS-north is identical to GMOS-North (MOS and CCD)
GNIRS is a 1-5um spectrograph (these are big instruments)

GNIRS on Gemini South

T-ReCs is a 5-25 um camera

NICI is a 1-5 um dual imaging AO coronograph for finding extrasolar planets
(in a similar fashion to my SDI cameras)