INAF - Astronomical Observatory of Padova

INAF - Astronomical Observatory of Padova is one of the main structures of the National Institute of Astrophysics (INAF). The main activity of the Observatory is to perform scientific research in various  fields of Astrophysics. The Observatory also contributes to  advanced education, assists in the dissemination of knowledge and implements project of education and outreach of Astronomy.

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The 182 cm telescope


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The telescope and its instruments are operated by the Astronomical Observatory of Padua that is part of the Istituto Nazionale di Astrofisica (INAF). The 182 cm telescope is located at Cima Ekar (Asiago) and is the largest astronomical telescope in Italy. It is dedicated to Nicolas Copernicus and has been in operation since 1973.  It is used for optical imaging and low to medium resolution spectroscopy using two main instruments: AFOSC and an Echelle spectrograph.
The telescope and its instruments are operated by the Astronomical Observatory of Padua that is part of the Istituto Nazionale di Astrofisica (INAF).


Longitude: 11° 34' 08.397" E  -  Latitude: 45° 50' 54.894" N  -  Altitude: 1376.2m



Optical design of the telescope is a Classic Cassegrain with equivalent focal number f/9.
The primary mirror M1 (made of Schott Duran 50) has a diameter of 182cm.
The main characteristics of the mirrors:
M1 M2
  Total mass 1500 Kg   Total mass 67.4 Kg
  Diameter 1820 mm
  Diameter 580.0 mm
  Thickness (external ring) 300 mm   Thickness (external ring) 110.3 mm
  Diameter of central hole  Ø 383 mm
  Radius of curvature 10786 mm   Radius of curvature  4594.8 mm
  Focal length 5393 mm   Theorical distance M1 - M2  3855 mm
  F/number   f/3
  Sagitta 38 mm
An active system for the movements of the secondary mirror is implemented. This unit, in addition to the standard focusing, allows one to control both X and Y positions of M2 and tilt angle ALFA, BETA. The whole system is controlled by a dedicated PC. The mirror is periodically re-coated with aluminium using the vacuum chamber at Cima Ekar


The limit of pointing for the declination axis is dependent on the altitude of the target. The minimum altitude is fixed at 20 degrees by both software and hardware limit switch. It is strongly advised that this position never be reached.The pointing accuracy is better than 1 arcmin all sky. The coordinates are read by two absolute encoders with a resolution of approximately 4 arcsec.

The Cassegrain Focus

The Cassegrain Focus (f/9, scale 12.6 arcsec/mm at about 20 cm from the rear main flange) is the main focus of the telescope. Focusing is performed by moving the secondary mirror along the Z axis; this movement is controlled  by a dedicated PC.

The Nasmyth Focus

A 45 degree tertiary mirror can be inserted to deviate the beam to the Nasmyth focus in the East side of the fork.


The dome of the telescope is on the third floor of the telescope building and has a diameter of 15 m.
The building is equipped with an external elevator to enable maintenance of the dome. Aperture and rotation of the dome are controlled by the TPS (Telescope Pointing System) software.
In addition to the observing floor the building contains offices, mechanical and electronic laboratories and a small kitchen.


Pointing of the telescope and auto-guiding is performed using TPS software.
During observations the dome is automatically rotated such that the dome window is always aligned with the telescope pointing.

See the Telescope Manual for details  (pdf file)


At the 182cm telescope two instruments are available: a low resolution spectrograph and imager (AFOSC) and an high resolution spectrograph (Echelle).
The two instruments are complementary for spectral resolution and are therefore mounted in turn at the telescope following the moon cycle (AFOSC being usually available during grey and dark time).


Since 1983 several CCD detectors have been installed at instruments' focal planes.
Currently only two detectors are used with the scheduled instruments.
Their characteristics and performances are reported at following link:

Further information on the 182 Telescope are available on:


Statistics of observing time at the 182cm telescope


(Time allocation, information for local accommodation, policy of the observations, observing constraints, acknowledgments)

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