Ground radiation and interference and their change with directions
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Ground Radiation and Interference and their change with directions. Chen Wang JinLin Han, XiaoHui Sun, Wolfgang Reich, WeiBin Shi. Outlines. Reasons to do How to do and what we did Observation done Ground radiation profile vs. Azimuth Ground radiation profile vs. Elevation

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Ground radiation and interference and their change with directions

Ground Radiation and Interference and their change with directions

Chen Wang

JinLin Han, XiaoHui Sun,

Wolfgang Reich, WeiBin Shi


Outlines
Outlines directions

  • Reasons to do

  • How to do and what we did

    • Observation done

    • Ground radiation profile vs. Azimuth

    • Ground radiation profile vs. Elevation

    • Ground radiation at North Celestial Pole (NCP)

    • Interference from Indian synchronous satellites (INSAT)

  • Summaries


Why to study ground radiation
Why to study ground radiation? directions

  • Set up ground radiation model  absolute calibration.

  • Set lower elevation limit for observations.

  • Identify surrounding interference sources.

  • More?


How to do
How to do? directions

  • Scan along azimuth at fixed elevations.

  • Scan along elevation at fixed azimuths.

  • Monitor the NCP.

  • Mapping satellites.


Observations done
Observations done directions

  • 36 scans along AZ

    • Generally, the separation of subscans is 2o (along EL ).

  • 12 scans along EL

    • typically EL = 5o– 81o , at a fixed Azimuth.

  • 24 scans at NCP

    • Some separate observations and a continual 34 hours observation.

  • 12 scans for Indian satellites

    • Four scans with size 10o *10o


Ground radiation and interference and their change with directions

Sky trajectory of observations directions

NCP

scans along EL

scans along AZ

Indian Satellites


Ground radiation and interference and their change with directions

I directions- AZ

Ground radiation vs. Azimuth

12

EL=10

14

12

16

14

14

14

18

16

16

I

20

18

16

18

20

20

18

20

AZ


Ground radiation and interference and their change with directions

I directions- AZ

Ground radiation vs. Azimuth

Jump, Why?

-Temperature?

-Radome foil?

12

EL=10

14

12

16

14

14

14

18

16

16

I

20

18

16

18

20

20

18

20

AZ


Ground radiation and interference and their change with directions

Ground Radiation along azimuth at low elevation vs. directions

the profile of the horizon of Nanshan Station

I- AZ

EL=14

I

EL=16

EL=18

EL=20

The elevation of horizon at different azimuth


Ground radiation vs elevation

350 directionso

40o

320o

70o

290o

90o

253o

120o

240o

140o

210o

180o

Ground radiation vs. Elevation

  • 12 scans distribute from 0o to 360 o

  • Observing avoid the Galactic emission (the same to scans along AZ)


Ground radiation and interference and their change with directions

SCAN 3578 directions

AZ = 320o

EL = 5o - 81o

  • Intensity changes exponentially with EL < 40o, and linearly with EL > 40o.

  • U & Q seems more complicated.


Ground radiation at ncp
Ground radiation at NCP directions

  • The position of the NCP at sky keeps constant, so the ground radiation at NCP should be constant approximately too.


Ground radiation and interference and their change with directions

34 directionshours

Each of the four channels changes regularly daily

-there are some strong sources near the NCP


Ground radiation and interference and their change with directions

UQ map of the NCP (not calibrated) directions

  • Except the ground radiation, the UQ map of sky emission should be a circle. (see the PhD thesis of Maik Wolleben)


The effect of satellites
The effect of satellites directions

  • Strong stripes in the south sky

  • Indian synchronous satellites at 4 positions, which all can emit in C-Band (just including our observing frequency).

  • Before the method to deal with stripes found, we have to observe avoid the south sky


Ground radiation and interference and their change with directions

INSAT_2DT directions

Intensity

INSAT_2DT

Polarization Intensity


Ground radiation and interference and their change with directions

G193B directions

G195B

I1 channel

I2 channel

U channel

Q channel

I1 channel

I2 channel

U channel

Q channel

The stripes of satellites on the south sky at Nanshan Station


Summaries
Summaries directions

  • Along AZ direction, the profile of GR corresponds with the profile of horizon.

  • Along EL direction, GR changes exponentially at EL < 40 and linearly at EL > 40.

  • The emission (including sky emission and ground radiation) at NCP changes daily. It’s hard to separate these two components.

  • Indian synchronous satellites disturb strongly to the observation at south sky

  • The research has just been done a little. More observation and study are needed.


The end

THE END directions