scholarly journals Optical Observations of the Crab Pulsar, and Searches for other Optical Pulsars

1971 ◽  
Vol 46 ◽  
pp. 87-90
Author(s):  
Jerome Kristian
Keyword(s):  
Optical Properties ◽  
Light Curve ◽  
Total Energy ◽  
Crab Nebula ◽  
Optical Observations ◽  
Crab Pulsar ◽  
Time Variations ◽  
Optical Wavelengths ◽  
High Degree ◽  
The Crab Nebula

The optical properties of the Crab nebula pulsar are reviewed. The Crab nebula pulsar has a high degree of constancy at optical wavelengths. No time variations over short or long periods have been detected; the light curve is nearly the same in all colors. The intensity and color of the pulsar are V = 16.5, B − V = +0.5, U − B = −0.45 and V − R = −0.75. There is no precursor as found at radio wavelengths and the main pulse contains 65 per cent of the total energy. No lines have been detected.Searches for other pulsars have been unsuccessful.

scholarly journals Results of Optical Timing Measurements of the Crab Nebula Pulsar

1971 ◽  
Vol 46 ◽  
pp. 142-150
Author(s):  
C. Papaliolios ◽  
N. P. Carleton ◽  
P. Horowitz
Keyword(s):  
Solar System ◽  
Light Curve ◽  
Magnetic Dipole ◽  
Crab Nebula ◽  
Time Of Arrival ◽  
Crab Pulsar ◽  
Optical Pulses ◽  
Dipole Radiation ◽  
Timing Data ◽  
The Crab Nebula

Absolute time of arrival measurements were made of the optical pulses from the Crab pulsar between September 1969 and April 1970; they were corrected to the solar system barycentre. The fit to the timing data indicates that the slowdown is due to magnetic dipole radiation, but there are significant deviations indicating the presence of small fluctuations and major jumps. There is no evidence of the quasi-sinusoidal behaviour reported by Arecibo. These measurements allowed an integrated light curve to be constructed with high precision.

scholarly journals Properties of individual X-ray sources: (Invited discourse)

1970 ◽  
Vol 37 ◽  
pp. 59-80
Author(s):  
Laurence E. Peterson
Keyword(s):  
Power Law ◽  
Crab Nebula ◽  
Optical Observations ◽  
X Rays ◽  
X Ray ◽  
Upper Limits ◽  
Time Variations ◽  
Γ Rays ◽  
The Crab Nebula

Observations to determine the spectra and time variations of hard X-rays from cosmic sources have been made from balloons and from the OSO-III satellite. These data have been obtained using actively collimated scintillation counters with apertures between 6 and 24° FWHM, areas between 10 and 50 cm2 and which operate over the 10–300 keV range. The Crab Nebula has been observed on three occasions over a 22-month period between September 1965 and July 1967. The power law spectrum has a number index of 2.0 ± 0.1. No long-term changes were observed over the 30–100 keV range with a limit at 3%/yr. A balloon search with a 10 cm2 Ge(Li) detector for X-ray lines at 62.5 keV, 110 keV and 180 keV due to heavy element radioactive decays which would be produced in the initial Crab explosion based on the Cf254 hypothesis has resulted in upper limits at about 10−3 γ-rays cm2-sec. This is about a factor of 20 above the predicted levels. Simultaneous X-ray and optical observations of SCO XR-1 from OSO-III confirm that X-ray and optical flaring are indeed coincident phenomena, and that although the X-ray intensity increases about a factor of two during the flare, the equivalent temperature of the excess radiation is nearly the same as that of the quiescent object. Upper limits, 95% confidence, on the flux of M-87 at 40 keV have been obtained. These are inconsistent with the flux of 1.2 × 10−4 photons/cm2-sec-keV reported in the literature. CYG X-1 has been observed to have a power law of number index 2.0 ± 0.2. The OSO-III has observed a number of sources in the southern skies including NOR XR-2 and the variable source Centaurus XR-2.

scholarly journals Radio Observations of the Crab Nebula Pulsar

1971 ◽  
Vol 46 ◽  
pp. 73-83
Author(s):  
F. D. Drake
Keyword(s):  
Multipath Propagation ◽  
Crab Nebula ◽  
Crab Pulsar ◽  
Great Intensity ◽  
Radio Observations ◽  
Radiated Power ◽  
Propagation Effects ◽  
The Crab Nebula

The radio properties of the Crab Nebula pulsar are reviewed. The pulsar lies at the centre of the Crab Nebula and has a period of 33 msec. Its increase in period with time releases an amount of energy which is equal in magnitude to the total radiated power. Instabilities in the period of the Crab pulsar have been discovered with timescales ranging from days to months. The length of the pulse increases at longer wavelengths due apparently to multipath propagation effects. A characteristic of the Crab pulsar is the great intensity of the occasional pulse.

scholarly journals Superfluidity in Neutron Stars

1974 ◽  
Vol 53 ◽  
pp. 151-165
Author(s):  
George Greenstein
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Crab Nebula ◽  
Crab Pulsar ◽  
X Ray ◽  
Effects Of Rotation ◽  
The Crab Nebula

We present a short Cook's tour of the possible effects of rotation coupled with superfluid properties of neutron star interiors. A suggestion is made to take advantage of forthcoming lunar occultations of the Crab Nebula in order to search for blackbody X-ray emission from the Crab pulsar.

scholarly journals Faraday Rotation of the Crab Pulsar Radiation

1971 ◽  
Vol 46 ◽  
pp. 118-118
Author(s):  
R. N. Manchester
Keyword(s):  
Faraday Rotation ◽  
Radio Astronomy ◽  
Crab Nebula ◽  
Position Angle ◽  
Crab Pulsar ◽  
Astronomy Observatory ◽  
Pulsar Radiation ◽  
Rotation Measure ◽  
The Mean ◽  
The Crab Nebula

During April, 1970, the 300-ft telescope of the National Radio Astronomy Observatory was used to determine the mean polarisation of the Crab Nebula pulsar radiation at several frequencies around 400 MHz. The position angle of the highly polarised precursor measured at each frequency, corrected for ionospheric Faraday rotation and plotted against inverse frequency squared is shown in Figure 1. The observed variation of the position angle with frequency is consistent with Faraday rotation of the plane of polarisation with a rotation measure of −40.5 ± 4.5 rad/m2. This value is of the same sign but larger than the rotation measure for the nebular radiation in the vicinity of the pulsar.

Optical Observations of the Crab Nebula Pulsar

1969 ◽  
Vol 157 ◽  
pp. L1 ◽  
Author(s):  
E. Joseph Wampler ◽  
Jeffrey D. Scargle ◽  
Joseph S. Miller
Keyword(s):  
Crab Nebula ◽  
Optical Observations ◽  
The Crab Nebula

The Crab pulsar echoes

2000 ◽  
Vol 177 ◽  
pp. 499-502 ◽  
Author(s):  
F. Graham Smith ◽  
A.G. Lyne
Keyword(s):  
Electron Density ◽  
Continuous Monitoring ◽  
Crab Nebula ◽  
Outer Part ◽  
Dispersion Measure ◽  
Crab Pulsar ◽  
The Past ◽  
The Crab Nebula

AbstractObservations over an eight month period from July 1997 to March 1998 show echoes following the radio pulses, and unusual changes in dispersion measure. We interpret this remarkable and complex event as refraction and dispersion in an ionised shell in the outer part of the Crab Nebula. The shell is remarkably compact; it has a electron density of about 103– 104cm−3and a thickness of about 3 × 1011m. Similar events have been noticed on several other occasions during the continuous monitoring of the Crab pulsar over the past 25 years.

scholarly journals The Crab Pulsar and Nebula as Seen in Gamma-Rays

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 448
Author(s):  
Elena Amato ◽  
Barbara Olmi
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Crab Pulsar ◽  
Gamma Ray Astronomy ◽  
Very High Energy ◽  
Energy Gamma ◽  
The Crab Nebula ◽  
The Impact ◽  
Very High

Slightly more than 30 years ago, Whipple detection of the Crab Nebula was the start of Very High Energy gamma-ray astronomy. Since then, gamma-ray observations of this source have continued to provide new surprises and challenges to theories, with the detection of fast variability, pulsed emission up to unexpectedly high energy, and the very recent detection of photons with energy exceeding 1 PeV. In this article, we review the impact of gamma-ray observations on our understanding of this extraordinary accelerator.

X-Ray and Optical Observations of the Pulsar NP 0532 in the Crab Nebula

Nature ◽  
1969 ◽  
Vol 222 (5195) ◽  
pp. 728-730 ◽  
Author(s):  
H. BRADT ◽  
S. RAPPAPORT ◽  
W. MAYER ◽  
R. E. NATHER ◽  
B. WARNER ◽  
...  
Keyword(s):  
Crab Nebula ◽  
Optical Observations ◽  
X Ray ◽  
The Crab Nebula
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