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Identification
Hosting Legal Entity
National Institute for Astrophysics
Location
Via Fiorentina 3513, Medicina radiotelescopes, Villafontana di Medicina (Bologna), PO: 40060 (Italy)
Structure
Type Of RI
Distributed
Coordinating Country
Italy
Status
Status
Current Status:
Operational since 1983
Scientific Description
This radiotelescope of 32m in diameter is one of the big infrastructures of the Italian National Institute of Astrophysics (INAF), conceived to work within the International VLBI networks both for Astronomy and Geodesy. It is a node of the European VLBI Network, (EVN), Joint Institute for Very Long Baseline Interferometry in Europe (JIVE), and International VLBI Service for Geodesy and Astrometry (IVS).A qualifying capability of this antenna is the frequency agility (i.e. the capability to change frequency in a completely automatic way, and in a very short time, ranging from 4 seconds to 4 minutes). Moreover, it is equipped with high velocity fibre optics connection, which allows the data transfer in real time (eVLBI).Equipment:The frequency range covered by existing receivers is 1.3 to 26.5 GHz.Surface accuracy is 0.6 mm at Elevation=60o.Pointing accuracy is about 8 arcsec.Sensitivity:1) 20 mJy with 1 sec of integration has been proved in making a continuum survey at 21GHz by using the On Fly Technique (OTF).2) 15 mJy with 1 sec of integration has been proved in making a continuum survey at 5GHz by using on the On Fly Technique (OTF).3) In spectroscopy mode, sensitivity of few mK with very long integrations has been proved in the past.Single-dish observations are performed in continuum mode (including polarimetry) and spectroscopy.New Pointing System and Acquisition Programs (ESCS, Enhanced Single-Dish Control System), allows for different observational modes (on-off, on the fly, mapping, tracking of motu proprio objects like debris, space probe, etc.).Back-ends include a four-input total power with input bandwidth up to 2 GHz and acquisition time down to 1 msec, digital spectrometers.Access:The commitment in VLBI networks (EVN, IVS) covers about 4 months/yr (30%).About 10% of time is for observations in conjunction with the antenna in spaceRadioAstron (project of the Russian Academy of Science) on the basis of a MoU.The remaining time (60%) is used for single-dish observations in continuum (blazar variability, monitoring of FERMI and PLANCK sources, large-scale surveys) and spectroscopy (masers OH, H2O, methanol) and for geodesy projects.A call for proposal is issued to the international community twice a year and proposals are evaluated on scientific merit by a Time Allocation Committee appointed by INAF.The observatory provides assistance through a staff of engineers and astronomers.The running costs are funded by INAF.

RI Keywords
Astrophysics, Engineering, VLBI, Radioastronomy
Classifications
RI Category
Telescopes
Scientific Domain
Physics, Astronomy, Astrophysics and Mathematics
ESFRI Domain
Physical Sciences and Engineering
Equipment
32m Medicina radiotelescope

The Northern Cross is, currently, composed of two perpendicular arms that are 564 m long (East-West) and 640 m long (North-South) and it has a useable total surface area of 30000 m2. Thanks to this vast area the antenna is capable of detecting very weak radio sources. The antenna observes "through" a 2.7 MHz wide window, centered at 408 MHz and it has been mainly used to effect high sensitivity sky surveys and, thus, to produce large radio-source catalogues, which have been and are still today of fundamental importance for astronomical research. Furthermore the "Cross" has been used for pulsars research and for the spectrometric study of interstellar dust (emission line of ionized hydrogen and of ionized carbon). Currently the instrument is being converted and upgraded in order to meet the international SKA (Square Kilometre Array) program requirements. The ultimate goal ia a next generation radiotelescope with a useable total surface area of 1 km2 area. The "Cross", in fact, represents an ideal test ground for SKA technologies and data acquisition systems. The 32 m parabolic antenna is employed both for single dish observations and for interferometry. In interferometry it works together with the other EVN (European Very Long Baseline Interferometry Network) antennas, installed all over Europe, in order to produce very high resolution images, which are quite useful for detailed radio sources studies. The radiotelescope can receive radio signals within the 1.4 ÷ 23 GHz range. In single dish, it is mainly used for : H2O and methanol maser spectrometry, monitoring of extragalactic compact sources flux variability, galactic polarimetric surveys, studies of comets, extrasolar planet research, and radar monitoring of Near Earth Objects (in collaboration with the NASA) The astronomical interferometric observations are, also, used for geodynamic studies. The VLBI techniques, in fact, allow measurement of the distance between the various antennas with a millimetric degree of accuracy. It is therefore the most precise way of monitoring and studying the movements of the Earth's crust.

Collaborations
Networks
European VLBI Network (EVN)
International VLBI Service for Geodesy & Astrometry (IVS)
Date of last update: 24/03/2017
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