Phone: (+34) 949290311 Fax: (+34) 949290063

Cerro de la Palera s/n 19141 - Yebes Guadalajara Spain

Phone: (+34) 949290311 Fax: (+34) 949290063 Email: b.vaquero@oan.es

SPIDER

The Center for Technological Developments (CDT) is a

branch of the National Geographic Institute of Spain. The

new Radio Telescope is opened for the scientific

community interested in Radio Astronomy.

The goal of SPIDER is to provide the opportunity for students

and visitors to operate a real radio telescope, in the

environment of the Yebes observatory, as the 40 meter dish is

not accessible to them. The instrument can be operated

remotely via internet. Many of the applications are still to be

designed, in coordination with other EVN observatories

which are part of the network of Visitor Centres (VC-Net)

sponsored by the EC FP7 project “RadioNet”.

Services Yebes Technological Development Center

Centro de Desarrollos Tecnológicos de Yebes

Instituto Geográfico Nacional (Spain)

Yebes Technological Development Center

SPIDER Main SpecificationsSPIDER Main SpecificationsSPIDER Main SpecificationsSPIDER Main Specifications

DiameterDiameterDiameterDiameter 2.3m

Angular resolutionAngular resolutionAngular resolutionAngular resolution 7deg @ 1420MHz

Rx BandwidthRx BandwidthRx BandwidthRx Bandwidth 2.4MHz

Rx Frequency channelsRx Frequency channelsRx Frequency channelsRx Frequency channels 256

Can be used remotelyCan be used remotelyCan be used remotelyCan be used remotely

SPIDER (“Small Parabolic Instrument for Demonstration,

Education, and Research”) is one of the outreach activities

performed st Yebes Observatory in Guadalajara. Built by the

Swedish company Are Elektronik following the principles of

the SALSA instrument developed by Onsala Space

Observatory, SPIDER is a fully operational 2.3 meters radio

telescope equipped with an L-band (21cm – 1420MHz)

receiver and a spectrograph (352 channel correlator, 2.4MHz

total bandwidth). The beam width is 7 degrees. A low noise

preamplifier is mounted at the antenna focus and a coax cable

feeds the signal to a cabinet which contains the receiver,

power supplies and a modem. In the antenna vertex a small

dipole antenna is installed for calibration purposes. This radio

telescope is ideal for observing hydrogen in our galaxy, the

Milky Way. Radio observations are not affected by the

interstellar dust so it is possible to study the galaxy structure.

The main aim is to map the spiral arms of the Galaxy.

Radio Astronomy outreach at Radio Astronomy outreach at Radio Astronomy outreach at Radio Astronomy outreach at

the CDTthe CDTthe CDTthe CDT

Hydrogen 21cm line Hydrogen (H) is the most abundant element in the Universe (it is

also abundant in our Galaxy). When a hyperfine transition occurs

the atomic Hydrogen falls to the ground state and it emits energy

in the form of electromagnetic radiation with a frequency of

1420MHz (λ=21cm).

This spin flips probability is once every 10 million years. It

should be hard to detect but huge amounts of atomic hydrogen in

the Galaxy makes the 21cm line easy to detect.

Radio Astronomy Observations

Observations in the Galactic disk. The purple line is the line of

sight. Radio lines in the spectrum correspond to spiral arms. They

are affected by the Doppler effect what gives us information

about speed of movement and also distance.

The Earth and the Sun are situated in one of the Spiral arms

(Orion arm), approximately 25000 light years from the center of

the Galaxy.

To obtain the structure of the Milky Way it is necessary to

observe at different galactic longitudes and, from this observa-

tions, calculate the distance to clouds of hydrogen.

Control ComputerControl ComputerControl ComputerControl Computer

VNC remote access VNC remote access VNC remote access VNC remote access

Control System and Software The Onsala software Qradio is used for controlling the radio

telescope. This software communicates with “Kstars”.

SalsaJSalsaJSalsaJSalsaJ

Milky Way artist’s viewMilky Way artist’s viewMilky Way artist’s viewMilky Way artist’s view

rotationGalactic

Perseus armCygnus arm

Orion armSunl=270

l=0

Quadrant I Quadrant IV

Sagittarius arm

Centaurus arm

C

Quadrant IIQuadrant III

l=90

l=180

10 kpc = 32 600 light-years

SpectrumSpectrumSpectrumSpectrum

By means of VNC it is possible

to access SPIDER remotely.

Analysis of the observations

Sample of acquired spectrumSample of acquired spectrumSample of acquired spectrumSample of acquired spectrum

Feeder

Parabolic Dish

Receiver

Tetrapode

Az motor

El motor

SpiderSpiderSpiderSpider

SubsystemsSubsystemsSubsystemsSubsystems