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PSC Data Analysis Matthew Catron, Bryan Wright, & Kristen Royse Rowan County Senior High School RFI Abstract
Despite the vast research by pulsar astronomers, little is known about pulsars. While the Green Bank Telescope, the largest steerable radio telescope in the world, was being repaired it collected 30 terabytes of data. Radio astronomers allowed students who passed two tests through the Pulsar Search Collaboratory to analyze this data. Through analysis of this data two previously confirmed pulsars J1743-1351 and J1854 1421 along with various known sources of radio frequency interference were examined. These findings are beneficial to radio astronomers because it provides them with observations of pulsars at later dates.
Data Analysis
The pie chart below conveys the variety of observations in the data. Almost 87% of the data was ambient noise, with known sources of radio frequency interference making up the other 13%; known pulsars accounted for less than 0.03%.
RFI Noise Known Pulsars
Introduction
Students at Rowan County Senior High School are offered an elective in pulsar astronomy. The instructor, Mrs. Carter, has taught our group what is needed to be admitted into the Pulsar Search Collaboratory. Our group learned how to analyze Fast Fourier Transmission plots and has become amateur radio astronomers. Our group can now effectively analyze graphs of radio signals. Instead of merely identifying known pulsars, our group can label noise, known sources of RFI and yet-to-be discovered pulsars. Our group was shown how to recognize harmonics of radio sources. Mrs. Carter also instructed our group in calculating the age of known pulsars, given the appropriate information. Noise; 6928; 86,79529%
Figure 2
RFI; 1052; 13,17965% Known Pulsars; 2; 0,02506%
Figure 4
The GBT collects weak radio waves emitted by distant pulsars. However, our world is filled with radio sources. Humans generate radio sources that interfere with weak pulsar signals, examples include: a car radio, satellite TV, and cell phones. Less obvious radio sources, such as power lines, also emit radio waves. Radio frequency interference, RFI, contaminate data collected by the GBT and can look like a pulsar signal. Often, RFI will appear promising in the Fast Fourier Transform plot. Figures 4 and 5 contain RFI at frequencies of 60 Hz and a 600 Hz harmonic, these frequencies are associated with the radio emissions of power lines. A harmonic is a signal or wave whose frequency is an integral multiple of the frequency of some reference signal or wave.
Pulsar J1743-1351 Figure 1
Above is a data plot for pulsar J1743-1351. J1743 1351 was first reported in 1985, by Kramer and Live in
Long Term observations of 374 Pulsars.
J1743-1351 has a 405 millisecond period. Dispersion Measure is a measure of how disperse the signals from J1743-1351 are. The dispersion measure checker on the Pulsar Search Collaboratory web site calculates J174-1351 is located at the galactic coordinates of 12.6 degrees longitude and 8.3 degrees latitude, with a dispersion measure of 115.449. J1743-1351 is 2.9kpc from Earth. The calculated age for this pulsar is only 1720 years, which is too young to have a period of 405ms. This can be attributed to faulty P-dot calculation.
= =
= 1720 years
Pulsar J1854-1421
Pulsar J1854-1421has a galactic longitude of 20.4 degrees, a galactic latitude of -7.0 degrees, and a dispersion measure (DM) of 130.0cm^-3 pc. The DM checker on the PSC main page calculates pulsar J1854 1421 is 3.6 kpc from earth. The DM is within the maximum distance for this direction of sky. The characteristic age of pulsar J1854-1421 is calculated by the following equation. =
= 56 years
This age means there must be a problem with the values used. The period derivative for J1854-1421 is 3.2443X10^-10, meaning that pulsar J1854-1421 is slowing down extremely fast, or the period derivative was inaccurate.
Figure 3 Figure 5 Sky Map
After looking over the graph of the analyzed pointings, the group noticed that most of the data sets have declinations of either -14:00 or 2:00 with varying right ascensions. This is a result of the Earth’s rotation as the Green Bank Telescope sat stationary while undergoing repairs.
Figure 6 Sky Map
400 200 0 0 -200 -400 -600 -800 -1000 -1200 -1400 -1600 -1800 500 1000 1500 2000 2500 Ряд1