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The energy source of the anomalous X-ray pulsars (AXPs) is not understood, hence their designation as anomalous. Unlike binary X-ray pulsars, no companions are seen, so the energy cannot be supplied by accretion of matter from a companion star. The loss of rotational energy, which powers radio pulsars, is insufficient to power AXPs. Two models are generally(More)
  • F Hulleman, A F Tennant, M H Van Kerkwijk, S R Kulkarni, S K Patel
  • 2001
We present near-infrared and optical observations of the field of the Anomalous X-ray Pulsar 1E 2259+58.6 taken with the Keck telescope. We derive a subarcsecond Chandra position and tie it to our optical reference frame using other stars in the field. We find a very faint source, K s = 21.7 ± 0.2 mag, with a position coincident with the Chandra position.(More)
  • F Hulleman, M H Van Kerkwijk, F W M Verbunt, S R Kulkarni
  • 2000
We present Keck R and I band images of the field of the anomalous X-ray pulsar 1E 2259+58.6. We derive an improved X-ray position from archival ROSAT HRI observations by correcting for systematic (boresight) errors. Within the corresponding error circle, no object is found on the Keck images, down to limiting magnitudes R = 25.7 and I = 24.3. We discuss the(More)
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