The Secret Behind the Nobeyama
Radioheliograph’s Excellent Performance
The Nobeyama Radioheliograph is a radio telescope for solar
observation. “Helio” means the Sun, and “graph” means imaging
instrument. The 84 parabolic antennas with diameters of 80 cm arearrayed in a T shape, 490 m east to west and 220 m north from thecenter of this line, to form an interferometeric array telescope. In 2015,
management of the radioheliograph was reassigned to the Institute forSpace-Earth Environment Research of Nagoya University, but it has
persisted in conducting continuous observations of the Sun for 8 hours
every day. Over the past 10 years, the operation rate is more than
99 %. This is the highest operation rate for an observational telescopein Japan.
The surface of the Sun looks calm, but strong activity occurs near thesurface. High energy particles are produced by explosive phenomena
around sunspots (solar flares). These spiral around the magnetic fieldlines of the sunspots and produce very strong radio waves. The
radioheliograph catches these radio waves to ascertain the generation
mechanisms for these high energy particles. Research into various
phenomena happening on the surface of the Sun continues throughcooperation with the Nobeyama Radio Polarimeters, the solar
observation satellite “HINODE”, and solar telescopes located aroundthe world including optical telescopes in Mitaka Campus.

Let's try to understand the structure of these radio telescopes andinvestigate the secrets behind their high accuracy and sensitivity by making apaper model of one of these telescopes.

Main Performance Specifications
Main reflector diameter: 80 cm
Number of antennas: 84
Deployment: T shape (490 m east to west, 220 m north to south)
Observational frequencies: 17 GHz (left-handed and right-handed
circular polarization), 34 GHz (intensity only)
Field of view: Entire solar disk *The angular diameter of the Sun isabout 1900 arcsec.
Angular resolution: 10 arcsec. (17 GHz), 5 arcsec (34 GHz)Time resolution: 0.1 second (active periods), 1 second (quiet periods)

Other Solar Observation Instruments in Nobeyama
Nobeyama Radio Polarimeters
These observe the Sun at multiple
frequencies in the microwave range,such as 1, 2, 3.75, 9.4, 17, 35, and 80
GHz. They can discern the totalincoming flux and the degree ofcircular-polarization to investigate
solar activity. In particular, 3.75 GHzband observations have continued forover 60 years since 1951.

NobeyamaInterferometers
The red antennas in the
background observed 160
MHz (1970-1989), and theantenna in the foregroundobserved 17 GHz (1971-Picture: Nobeyama Radioheliograph and 45-m Radio Telescope1992). Now, these have finished observations and have been removed. But
they’re still being put to use for parabola demonstrations; the 160 MHz
antennas were taken to the Nishi-Harima and Misato Observatories, and the
17 GHz antennas are now in Nobeyama, Mitaka, etc.

(c) NAOJ

Let’s Build a paper model of

Sub-reflerctor
supportMain reflector (indide perimeter)

Nobeyama RH (1/4)(hone side)(sub-reflector side)

Sub-reflector
Sub-reflector stay

Main reflector collar

17GHz horn
Reciever box
Main reflector(periphery)

34GHz horn

Elevation axis(c) NAOJ

Let’s Build a paper model ofNobeyama RH (2/4)(reverse side)

Yoke (upper part)(front side)

0180
90

Elevation axispresser

Elevation axis
encoder(c) NAOJ

Let’s Build a paper model ofNobeyama RH (3/4)
Yoke (lower part)(reverse side)

Pedestal(front side)

Azimuth axis encoder
180150 120

90603003060

90120150

180(c) NAOJ

Let’s Build a paper model ofNobeyama RH (4/4)

Azimuth drive

Terminal box

Nobeyama Radio Heliograph1/10 Model
http://nro.nao.ac.jp/en/
Foundation(c) NAOJ

Let’s Build a paper model ofNobeyama RH (Instractions-1)
Material and tools: paper cutter, glue
1. Preparation: Copy the drawings (1/4, 2/4, 3/4, 4/4) on sheets ofpaper thick like Kent paper so that the outer frame forms 17 cm x26.5 cm rectangle. Cut out all the 24 componetns along the thicklines. Snick or hole where you have thick lines on the components.
Mountaion fold chain double-dashed lines and valley fold dashedlines.

way it hides itself behind the sub-reflevtor. Finally, wrap around thesub-reflector support with 6 sub-reflector stay ends (stays should
be interfolded beforehand) and fix them by gluing as to make up atripod, Glue down the tripod's legs on the main reflector (gluingpoints are marked on the reverse side).
4. Reciever box: Assemble the reciever box by mountain foldinig
and gluing, except the face with a large hole, and glue the mainreflector collar on the edge fo the large hole. At this stage the favcewith the main mirror collar should not be glued.
5. Elevation axis: Curl and make up the two axes. Glue theelevation axis encorder on an end of the axis and a presser on an
end of the remaining axis. Then leave them for the moment.

All the components in the can!

2. Main refrector: Glue the ends of the main refrector periphery to
make a cone (printed surface is the outside of it) and mountain foldthe inner side slightly. Glue the inside perimerter on the concaveside of the main reflector periphery. See to it that all the printed
surfaces come to the reverse side. Make up the 17 GHz horn
cylinder by curling up the component, thrust it into the disc holeand glue the nicked end on the non-printed side of the disc, now,
glue this unit from the concave side, on the center of the innerperimeter.
3. Sub-reflector: Rub the sub-reflector surface with your fingernail
unit it becomes convex. Prepare the 34 GHz horn by curling its
component as well as the sub-reflector support. Attach thesub-reflector so that one can see the printed surface. On anotherend of the sub-reflector support, attach the 34 GHz horn in theNow we have almost completed the sections!
6. Reciver box: Shape the upper part of the yoke. Insert theelevatioin axis from the outside hole of the yoke's upper part andthrough the hole of the receiver box, glue the parts as you prceedsteo by step. Glue the ends on the inner walls of the receiver box.
Use the axis with encorder on the yoke marked with ▲, and set
the encoder's 90 ° to meet the mark ▲. Finally glue the face withmain reflector collar to complete a box.
(c) NAOJ

Let’s Build a paper model ofNobeyama RH (Instractions-2)
7. Yoke: When you finished assembling the lowe part of the yoke,glue the azimuth encoder on the base of the yoke so that the 0 °faces the front face.

(the face with plate), then glue it. Now glue the pedestal onto thefoundation.
10. Terminal box: Make it by folding and gluing and attach it on thefar side of the pedestal.

8. Main reflector: Arrange the three sub-reflector stays to form aninversed Y when you mount the main reflector on the mainreflector collar.

Sub-reflector stays
should be mounted on
the marked pointd on
the reverse side of themain reflector.

9. Pedestal: Make a box by folding the faces of pedestal and moutthe azimuth drive on the top, ▲ mark should point the front side

Far side of the mainreflector.

Sub-reflector stays form
an inversed Y when seen
head-on.

Fill in antenna ID such as
W-22 in the ellipse.

34 GHz horn hides itself
behind the sub-reflector.
Front side of the reciever
box has squares on itssurface.

front side of the pedestal
has a plate.

(c) NAOJ