(First Edition)

Overview of Possible Experiments Right Ascension, Hour Angle, and Sidereal Time Galactic Center at Meridian Crossing Minimum Detectable signal Equivalent Black-body Temperature Calculating receiver Bandwidth Interferometer Symmetry Angular Dependence of Fringe-spacing Analyzing an Interferogram Optimum Interferometer Spacing A Benefit of Phase-Switching Focal-point Heating Square-Law Detection Phase-Switched Interferometer Finding the Local Meridian Antenna Temperature

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Solar Disturbances at 265 and 435 MHz
Amateur Radio Telescope at 1296 MHz
Salvaged Marisat Antenna project

Beginner's Microwave Radio Telescope
4 GHz TVRO Telescope: Preliminary Observations
Very Samll Radio Telescope at 4 GHz (horn)
4 GHz TRF (Tuned Radio Frequency) receiver
4 GHz Interferometr: 4 m Baseline
4 GHz interferometer: 28 m Baseline
Solar radius at 4 GHz: 28 m Baseline
Solar radius at 4 GHz: 4 m Baseline
Small 10 GHz Radio Telescope
The Moon at 11 GHz
Computerized Observations at 11 GHz
12 GHz Radio Telescope
Small 12 GHz Demonstration Radio Telescope
Backyard Radio Telescope
Multi-antenna Telescope
Home built Pyramidal Horn Antenna
Home built Wave-guide to Coax Adapter
Spiral Antenna Feeds
Slot vs Spiral antenna Feeds

Second Detector: Crystal or Vacuum Diode?
Build a Digitizer from an X-Y recorder
Temperature Effects in radio telescopes

Computer simulated signal Averaging
Signal Processing by Autocorrelatons
Signal Processing by Multiplication
Fourier Transform--Why?
Fourier Analysis--How?
Fourier Synthesis--How?

"The Galactic Center by Accident," by Sherri Aker
"The Sun's Temperature at 5 cm", by Na Han Chan
"Detecting the Galactic Center at 70 cm", by Jennifer Hatt
"Interferogram Visibility Function", by S. W. Lee
"Solar Temperature at 7.5 cm", by George Lo
"Verification of Fringe Periodicity of a Two Element Radio Telescope", by Michael Swift.

A. Spectra of Major Observable Objects
B. Meridian Crossings at Local Standard Time
C. Local Sidereal Time at zero Greenwich Mean Time
D. Sundial Corrections

Curriculum Vitae

p.1-38 Near the bottom of the page, the equation should have lambdas rather than l's.

p.3-30 The equation near the bottom of the page should have an equal sign rather than minus sign between V and the things to the right.

p.3-43 The schematic symbol for the inductor L is missing from the circuit.

p. 3-57 Near the bottom of the page, the gain should be 30.6 db rather than 36 db.

Also, at the very bottom of the page, L-subH and L should be divided by lambda's rather than by l's.

p. 6-1 The figure caption for Figure 1 should be modified so that it refers to only one graph rather than to two.

Also, on the same page near the bottom, the antenna gain should be 11.0 dbd rather than 110 dbd. An antenna with 110 dbd would surely be a wondrous thing!

In Chapters 1, 3, and 6, the expected visibility should be calculated from the square of the expression on the right hand side of the equations as shown. That is, the expression on the right hand sides of the equal signs should be squared to yield an observable value for the Visibility; the reason is analogous to the difference between an "amplitude" and an "intensity". Hence, the values obtained from the graphs on p.1-38 or 6-3 should be squared; the squared values are then to be compared with the "observed" visibility as obtained by using S_min and S_max. The affected pages are 1-37, 1-38, 3-26, 3-27, 3-29, 3-30, 6-13, and 6-15.

NB Percent difference between two numbers A nd B is calculated from 100|A-B|/0.5(A+B).

p. 3-26 The expected value of V is calculated from


p. 3-2 In our experiment, the expected value of V turns out to be (0.070)² (using only two significant figures and the absolute value), whereas the observed value turns out to be 0.057 on the basis of the data for November 15, 1987. The difference is approximately 15%, which is a little disappointing, but really not that unsatisfactory if we advert to the fact that this number was calculated from only one interferogram. But analysis of other interferograms, obtained between October 29 and November 23, 1987, yield values of V all thw way from (0.031)² to (0.068)², and one can be puzzled by such a spread in results.

p. 3-29 First, let us calculate the expected value of the visibility V as defined in the previous article. The wavelength is still the same, but the baseline length S_lambda in units of wavelength is now 400/7.5 = 53, whereas it was 2800/7.5 = 370 in Part 1. Substituting the values for the shorter baseline gives the value of V = (0.68)², whereas V for the longer baseline was (0.067)². In both calculations, the Sun is assumed to have an angular diameter of 0.5 deg. arc. Hence, if our interferometer is working properly (in particular, if both elements of the interferometer have identical gains and the noise signals from each element travel the same electrical distance) and if the Sun's angular size is as assumed, then appropriate analysis of the interferogram should give us a value of V = (0.68)² within, say, a few percent. This also assumes that we are observing with a narrow-band receiver, so that the wavelength is a fairly definite number.

p. 3-30 From the interferogram, S_max = 8.5 cm and S_min = 2.7 cm. The visibility V is now calculate from

V = (S_max - S_min)/(S_max + S_min)

and we obtain V = 0.52 as the 'observed' value. Comparing this with the 'expected' value of (0.68)² gives a percent difference of approximately 15%.

p. 6-13


p. 6-14 To find the expected visibility V, draw a vertical line at S_lambda = 53.3 to intersect the curve, and then an horizontal line to intersect the visibility axis. The expected visibility is found to be (0.68)² = 0.46 at the center of the interferogram.

The experimental and expected values in this case differ by approximately 10010.52-0.451/0.5(0.52+0.46) = 14%. As indicated in the article on p.3-29, this discrepancy is not unreasonable given all the uncertainties associated with the experiment.