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This page summarises observations and images of selected AXP star fields
AXP Stars 1E 2259+586 - Anomalous X-ray pulser (AXP) 4U 0142+615 - Anomalous X-ray pulser (AXP) Realtime Reference Images Future Project Stars
Anomalous X-ray pulsers (AXPs) have described by Dr Robert Duncan in an article in the Sky & Telescope magazine, January 2005 (pp 34-41). Many of them could be Magnetars - neutron stars (or pulsars) with a very strong magnetic fields. AXP's are so faint in visible light that normally only the world's largest telescopes have any chance to detect them. However these stars probably brighten dramatically during intense gamma-ray flares and may become visible to amateur astronomers with moderate equipment.
The two nearest known AXP's, 4U 0142+615 and 1E 2259+586 (both lying in Cassiopeia) are potential targets for regular observation. Robert Duncan estimates that the potential peak brightness could reach 12th magnitude, but rapidly fall to 15th mag after 5 minutes and 18th mag after 15 minutes. The bad news is that giant flares are likely to be rare (one per 10 to 100 years for a given AXP), however the frequency of optical flares is poorly understood. Whilst considerable luck would probably be required to witness a flare, simply providing information on the upper limits on the visible light flux during smaller flares might be scientifically useful.
Images of the area of these 2 AXP's are taken when opportunity presents, in the hope of potentially spotting an AXP flare up
Web Information: Dr Robert Duncan's website
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Base line images for the star field covering the AXP star 1E 2259+586 taken with C and R filters :
| 1E 2259+586 Star Field (Cassiopeia) | ||
| Annotated star field for 1E 2259+586 area Catalog position, +/- 2", is marked by mauve circle, No object can be seen at the centre of the circle, though a number of faint Mag+15 stars can just be seen around the inner circumference of the circle. |
1E 2259+586 Star field in R Band 30 sec exposure, magnitude limit +14.2 |
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| CCD Image 2 min exposure, C Filter 2004-12-29 00:51h UT (#81094) |
CCD Image 30 sec exposure, R Filter 2004-12-29 00:49h UT (#81093) |
Results
Follow-up images of 1E 2259+586 star field have been
taken on several occasions since Dec 2004, but no indications of activity have been
recorded.
| 1E 2259+586 star field : 2004-12-29 no sign of AXP (mag limit +15.5) |
1E 2259+586 reference star field (catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2004-12-29 00:51h UT (#81094) |
Baseline CCD Image, 2min, Filter 2004-12-29 |
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| 1E 2259+586 star field : 2005-01-05 no sign of AXP (mag limit +16) |
1E 2259+586 reference star field (catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-01-05 23:59h UT (#82131) |
Baseline CCD Image, 2min, Filter 2004-12-29 |
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| 1E 2259+586 star field : 2005-09-02 no sign of AXP (mag limit +17) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-09-02 21:55h UT (#93024) |
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| 1E 2259+586 star field : 2005-09-30 no sign of AXP (mag limit +17.8) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-09-30 21:22h UT (#85029) |
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| 1E 2259+586 star field : 2005-10-02 no sign of AXP (mag limit +17.8) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-10-02 22:37h UT (#96293) |
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| 1E 2259+586 star field : 2005-10-05 no sign of AXP (mag limit +16) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-10-05 20:25h UT (#97181) |
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| 1E 2259+586 star field : 2006-01-11 no sign of AXP (mag limit +15) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-01-11 22:09h UT (#110070) |
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| 1E 2259+586 star field : 2006-02-10 no sign of AXP (mag limit +15.3) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-02-10 20:26h UT (#114083) |
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| 1E 2259+586 star field : 2006-07-18 no sign of AXP (mag limit +x.x) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-07-18 01:12h UT (#130110) |
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| 1E 2259+586 star field : 2006-09-09 no sign of AXP (mag limit +16.3) |
1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-09-09 00:52h UT (#141426) |
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Base line images for the star field covering the AXP star 4U 0142+615 taken with C and R filters :
| 4U 0142+615 (Cassiopeia) | ||
| 4U 0142+615 annotated star field (Original Baseline Image) Catalog position is marked by mauve circle. No object can be seen at the centre of the circle, though a couple of Mag +15 stars can just be seen outside the circumference of the circle. |
4U 0142+615 reference star field (Improved image) Catalog position is marked by mauve circle. No object can be seen at the centre of the circle, though a couple of Mag +15 stars can just be seen outside the circumference of the circle. |
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| CCD Image 2 min exposure, C Filter 2004-12-29 00:43h UT (#81089) |
CCD Image 2 min exposure, C Filter 2005-09-02 21:46h UT (#95025) |
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Results
Follow-up images of 4U 0142+615 star field have been
taken on several occasions since Dec 2004, but no indications of activity have been
recorded.
| 4U 0142+615 star field : 2004-12-29 no sign of AXP (mag limit +16) |
4U 0142+615 reference star field (catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2004-12-29 00:43h UT (#81089) |
2 min exposure, C Filter 2005-09-02 21:46h UT (#95025) |
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| 4U 0142+615 star field : 2005-01-05 no sign of AXP (mag limit +17) |
4U 0142+615 reference star field (catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-01-05 23:59h UT (#82131) |
2 min exposure, C Filter 2005-09-02 21:46h UT (#95025) |
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| 4U 0142+615 star field : 2005-09-02 no sign of AXP (mag limit +17) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-09-02 21:46h UT (#93017) |
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| 4U 0142+615 star field : 2005-09-30 no sign of AXP (mag limit +17) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-09-02 21:46h UT (#95025) |
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| 4U 0142+615 star field : 2005-10-02 no sign of AXP (mag limit +17) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-10-02 22:32h UT (#96289) |
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| 4U 0142+615 star field : 2005-10-05 no sign of AXP (mag limit +16.7) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2005-10-05 20:19h UT (#97176) |
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| 4U 0142+615 star field : 2006-02-10 no sign of AXP (mag limit +15.8) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-02-10 20:19h UT (#114078) |
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| 4U 0142+615 star field : 2006-07-18 no sign of AXP (mag limit +14.8) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-07-18 01:18h UT (#130115) |
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| 4U 0142+615 star field : 2006-09-09 no sign of AXP (mag limit +16.5) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2006-09-09 00:56h UT (#141430) |
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Realtime reference images for AXP project stars are shown below.
They images are in the same orientation (S down, E right) that raw images are seen on the computer screen to facilitate a quick realtime visual comparison.
| 1E 2259+586 reference star field ( catalog position is marked by mauve circle) |
4U 0142+615 reference star field ( catalog position is marked by mauve circle) |
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| 2 min exposure, C Filter 2004-12-29 00:51h UT (#81094) |
2 min exposure, C Filter 2005-09-02 21:46h UT (#95025) |
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No current plans for adding further AXP stars to the observing programme.
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| This Web Page: | AXP Stars (Projects) |
| Last Updated : | 2015-05-15 |
| Site Owner : | David Richards |
| Home Page : | David's Astronomy Web Site |