NTT Technical Characteristics
| Location | |
| Location | 70° 43'54.272" W -29° 15'18.440" S |
| Altitude | 2375 m. |
| Optical Design | Ritchey-Chretien |
| Main Mirror | Schott Zerodur |
| Diameter | 3.58m, thin meniscus (24cm), |
| Active Optics | 75 actuators, 3 fixed points, 24 lateral actuators |
| Focal Ratio | f/2.2 |
| Secondary Mirror | Schott Zerodur |
| Diameter | 0.875m |
| Central Obstruction | 1.16m |
| Tertiary Mirror | Schott Zerodur |
| Major x minor axis | 0.840 x 0.600m |
| Nasmyth foci | |
| Field of view | 30arcmin, 336.6mm |
| Focal Ratio | f/11 |
| Plate scale | 5.35905 arcsec/mm |
| Image Quality | 80% energy in 0.15" in all telescope position |
General Lens Data (w/o adapter and instruments)
| Surfaces | 10 |
| Stop | 5 |
| System Aperture | Entrance Pupil Diameter = 3500 |
| Glass Catalogs | schott MISC |
| Ray Aiming | Off |
| Apodization | Uniform, factor = 8.00000E+000 |
| Effective Focal Length | 38501.74 (in air at system temperature and pressure) |
| Effective Focal Length | 38501.74 (in image space) |
| Back Focal Length | 21267.2 |
| Total Track | 6500 |
| Image Space F/# | 11.0005 |
| Paraxial Working F/# | 11.0005 |
| Working F/# | 11.00618 |
| Image Space NA | 0.04540561 |
| Object Space NA | 1.749999e-007 |
| Stop Radius | 1750 |
| Paraxial Image Height | 0 |
| Paraxial Magnification | 0 |
| Entrance Pupil Diameter | 3500 |
| Entrance Pupil Position | 6500 |
| Exit Pupil Diameter | 949.3438 |
| Exit Pupil Position (before image plane) | 10443.25 |
| M1-M2 distance | 5933.3 |
| M1-M3 distance | 1200 |
| M3-focus distance | 4100.6 |
| Radius of curvature in the image plane | 1898 |
| Field Type | Angle in degrees |
| Maximum Field | 0 |
| Primary Wave | 0.55 |
| Lens Units | Millimeters |
| Angular Magnification | 0 |
Surface Data Summary
| Surf | Type | Comment | Radius | Thickness | Glass | Diameter | Conic |
| OBJ | STANDARD | Infinity | Infinity | 0 | 0 | ||
| 1 | COORDBRK | - | 500 | - | - | ||
| 2 | STANDARD | SPIDER | Infinity | 0 | 3500 | 0 | |
| 3 | COORDBRK | - | 0 | - | - | ||
| 4 | STANDARD | Infinity | 6000 | 3500 | 0 | ||
| STO | STANDARD | M1 | -15400 | -5933.3 | MIRROR | 3500 | -1 |
| 6 | STANDARD | M2 | -4416.7 | 4733.3 | MIRROR | 805.1247 | -2.249926 |
| 7 | COORDBRK | - | 0 | - | - | ||
| 8 | STANDARD | M3 | Infinity | 0 | MIRROR | 552.5702 | 0 |
| 9 | COORDBRK | - | -4100.6 | - | - | ||
| IMA | STANDARD | Infinity | 0.0001346372 | 0 |
General Characteristics of the Rotator
| Angle of rotation | +/- 270 degrees |
| Maximum speed | 2 tr/min |
| Maximum acceleration | 0.3 degrees/sq s. |
| Maximum rotation speed | 0.3 degrees/min |
| Acceptable imbalance for instrument | 40 Nm |
| Safety brake | 1500 Nm |
| Inertia without instrument | 400 Kg*(sq.m) |
| Inertia with 2 tons of Instrument (EMMI) | 2300 Kg*(sq.m) |
Mechanical Characteristics of the Rotator
| Drive | one direct brushless cooled torque motor from ETEL |
| Outer diameter | 770 mm |
| Inner diameter | 556 mm |
| Thickness | 98 mm |
| Peak torque | 530 Nm |
| Running torque | 300 Nm |
| Water flow | 6 l/min |
| Inlet temperature | 2 to 3 degrees below ambient temperature |
| Temperature gradient | 1.5 degrees |
Electric Characteristics of the Rotator
| Electrical time constant | 6.2 ms |
| DC resistance | 37 ohm |
| Torque sensitivity | 132 Nm/A |
| Back EMF | 167 V/rad/s |
| Power input at stalled torque | 350 W |
| Supply voltage | 400 V (maximum) |
Encoder
| Heidenhain absolute encoder identical to the telescope |
| 32768 reference circle with hub |
| 2 scanning units |
| 2 AWE 1024.700 analysis electronics |
| 1 power unit NG100 |
Bearing
| Pre-stressed double race ball bearing from RKS with the following characteristics: | |
| Outer diameter | 1728 mm |
| Inner diameter | 1480 mm |
| Thickness | 90 mm |
| Pre-stress | 30 micrometers |
| Lubricator | SKF LGLT2 or AEROSHELL 16 |
| Friction | about 100 Nm |
| Torque on bolts inner ring | 25 Nm |
| Torque on bolts outer ring | 35 Nm |
Safety brake
| From ATV, electromagnetic with spring type 450 SE, with power supply ESE 1000 | |
| Brake torque | 3000 Nm |
| Power supply | 220/380 V |
| Max. power | 1000 W |
| Continuous power | 44 W |
Interface with the Instrument
| Back focal distance | 500 mm |
| Focalisation possibility | +/- 10 mm |
| Lateral displacement at the focal plane for max. load on adapter | 6.2 microns |
| Max. allowable tilt of the hub | 3" for a load of 800N at 400 mm from the fixation flange |
| Flange | outer diameter = 1630 mm |
| 48 holes M10, depth 12 mm on dia.1580 mm | |
| internal diameter = 1520 H7, depth 6 mm | |
| Max. load conditions | A) 2000 Kg between the flange and the focus (270 mm from the fixation flange) |
| B) 12000 Nm after the focus | |
| Max. axial runout under load conditions | 35 micrometers |
| Radial runout under load conditions | 35 micrometers |