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AZT-24 (Campo Imperatore) Stampa E-mail
giovedì 18 ottobre 2007
     

The AZT-24 Telescope

The AZT-24 is a 108 cm-aperture telescope located in the East dome of the Campo Imperatore Observatory.

Built by LOMO optical workshops for Pulkovo Observatory (St. Petersburg, Russia), it has been moved to Italy on 1995 and installed in its current location on 1997, in the framework of the SWIRT Project .

The telescope is equipped with the near-infrared camera SWIRCAM (1.1 - 2.5 μm ), provided by the Teramo Astronomical Observatory.

It is mainly devoted to the search for extragalactic Supernovae in the near-infrared ( SWIRT Project ): other projects concern stellar variability, galaxy luminosity, active galactic nuclei and minor bodies of the Solar System.

The AZT-24 is currently the only telescope on the italian ground to be equipped with near-infrared instrumentation.

  
-- See the AZT-24 Image gallery -- 
  • Technical data

Optical design

 

Ritchey-Chrétien with optional corrector

Flat focal plane field size

 

20' = 46 mm     ( 84' = 195 mm with corrector )

Primary mirror

diameter
focal length

1100 mm
4553 mm

Primary mirror weight

net
in the cell

280 Kg
1820 Kg

Secondary mirror

diameter

590 mm (Cassegrain focus)

Distance from primary mirror

 

2605.5 mm     (2611.0 mm with corrector)

Cassegrain equivalent focal length

 


7971 mm     (7965 mm with corrector)

Telescope frame type

 

equatorial (German)

Psf parameters @632.8 nm

on axis

74% total
66% total

light

energy

in 0''.52 circle
in 0''.31 circle

 

off axis

46% total
39% total

 

 

in 0''.52 circle
in 0''.31 circle

(These figures correspond to FWHM about 0''.25 on axis and 0''.30 at the field edge)

Mirror roughness

 

λ/30 rms

Focal plane offset from the instrumental flange

 


60.2 mm     (61.2 mm with corrector)

Telescope movements

 

DC motors

Pointing equipment

 

absolute encoders

 

resolution:

about 10'' (mechanical precision only)

 

speed:

rough guidance 75' per second
exact guidance 15''-16'' per second

Total telescope weight

 

32 tons (moving part 24 tons)

Note: In order to use the infrared camera, a 45° tertiary plane mirror ( M3) is currently installed which deflects at right angle the optical beam toward the detector.

 

  • The Station

The station is a remote site of Rome Astronomical Observatory located in the heart of the Appennino, in the Middle Italy, 2200 m above the sea level. Clic here to see how to reach Campo Imperatore (AQ).

The weather conditions are good but not excellent: on average, the 50 % of the nights is clear. However it should be noticed that this Observatory was built in the 1950s, when the site testing was not yet a science.

The darkness of the sky is very good, especially when the thermal inversion level lies below 2000 m a.s.l.: in this case, the clouds layer shields the Observatory from unwanted light coming from the valleys around. However, "darkness" is a relative concept in the near-infrared: indeed, the sky brightness is related primarily to the water vapour content of the atmosphere, rather than to the scatter of light by atmospheric aerosols. The typical sky brightness at Campo Imperatore amounts to 15.5, 14.5 and 11.5 mag/arcsec2 in the J, H and K band, respectively.

Measurements of the photometric conditions over long periods are here shown. They are stable within 0.06 mag for the J band (left), 0.1 mag for the H band (center) and 0.2 mag for the K band (right).


The measured FWHM is reported for a typical night (left diagram) a for a period of one year (central diagram). The FWHM lies typically between 2 and 3 arcsec: the seeing is less stable during the spring (around 120 days after the 1st of October). The right diagram shows the distribution of the measured FWHMs.
   

  

  • Observation time request

Any proposal must include people from at least one of the following institutions:

   -  Teramo Astronomical Observatory

   -  Rome Astronomical Observatory

   -  Pulkovo Astronomical Observatory

 

 
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