Pulsed and unpulsed light from the VELA and Crab pulsars
Abstract
Observations of pulsed and unpulsed light from the Vela and Crab pulsars are discussed which were made with an image photon-counting system at the f/15 focus of a 3.9-m telescope. Blue-light pictures of the Vela pulsar are presented which confirm the identification of the pulsar with the faint blue candidate star known as 'M' and clearly show residual emission in the pulsar light curve outside the two main peaks. The intensities of the Crab and Vela pulsars in B and U are given as a function of pulse phase, along with the apparent magnitudes in U and B of the time-averaged intensity of the Vela pulsar, estimates of the magnitudes of the pulsed and unpulsed light from each pulsar, and U and B light curves for the two pulsars. It is found that the steady light component from the Vela pulsar may be redder than the pulsed component and that the unpulsed background from the Crab pulsar amounts to about 3.6% of the peak intensity but a suprisingly large 25% of the mean pulsed light. Possible origins for the steady unpulsed light components are considered.
- Publication:
-
Nature
- Pub Date:
- November 1978
- DOI:
- 10.1038/276475a0
- Bibcode:
- 1978Natur.276..475P
- Keywords:
-
- Astronomical Photometry;
- Continuous Radiation;
- Crab Nebula;
- Electromagnetic Pulses;
- Pulsars;
- Light Curve;
- Stellar Magnitude;
- Visual Photometry;
- Astrophysics;
- ASTRONOMICAL PHOTOMETRY;
- CONTINUOUS RADIATION;
- CRAB NEBULA;
- ELECTROMAGNETIC PULSES;
- PULSARS;
- LIGHT CURVE;
- STELLAR MAGNITUDE;
- VISUAL PHOTOMETRY