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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
  1. GRB040223: Deep NIR NTT data re-analysis
  2. GRB 040223: XMM-Newton results
  3. GRB040223, improved XMM position
  4. IBAS Alert 1678: not a GRB
  5. GRB 031203: spectoscopic evidence for a 1998bw-like SN
  6. GRB 031203, possible supernova
  7. MASTER: RXTE GRB040308 optical observation
  8. IBAS results on a burst from SGR1806-20
  9. INTEGRAL detection of activity from SGR1806-20
  10. RXTE GRB040229 optical observation: no candidate
  11. GRB 040228 Optical observations
  12. IPN triangulation of GRB040228 (H3066, H3067)
  13. GRB040228 : KISO optical follow-up observation
  14. GRB 040228 (=H3066?,=H3067?): A Long GRB Localized by the HETE-2 WXM
  15. GRB 040223: Deep NIR NTT observations
  16. GRB 040223 : Optical observation (non-detection)
  17. XMM-Newton Images of GRB 040223
  18. GRB 040223, VLA observations
  19. GRB 040223: REM IJK Observations
  20. GRB 040223 XMM-Newton observation ...
  21. GRB 031203 XMM-Newton observation
  22. GRB 040223 : Planned XMM-Newton observation
  23. GRB 040106 : Planned XMM-Newton observation
  24. GRB 040223: further offline analysis
  25. GRB 040223: a long GRB detected with INTEGRAL
  26. GRB031111, optical observations
  27. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  28. GRB031203: Chandra Observations
  29. GRB040106, follow-up radio observations
  30. GRB040106: refined X-ray transient position
  31. Follow-up on IBAS GRB Alert 1379
  32. IBAS GRB alert 1379
  33. SN 2003dh/GRB030329 late-time optical spectroscopy
  34. GRB040106, Radio Observations
  35. GRB040106, likely optical afterglow
  36. GRB040106: Second Epoch Optical Observations
  37. GRB 031220: Optical observations of Chandra X-ray sources
  38. XMM-Newton Images of GRB 040106
  39. GRB040106: optical observations with REM+ROSS
  40. GRB031220: observation at Univercity of Miyazaki
  41. GRB 040106: Optical observations
  42. XMM-Newton observation of GRB040106
  43. GRB 040106 : Planned XMM-Newton observation
  44. GRB 040106 : peak flux
  45. GRB 040106 : a long GRB detected with INTEGRAL
  46. IPN triangulation of an intermediate burst from SGR1806-20
  47. GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
  48. GRB031220(=H2976): Observation with the Chandra X-ray Observatory
  49. GRB031225a triangulation (annulus)
  50. IPN triangulation of GRB031219 (large error box)
  51. GRB031220: Palomar Observations
  52. GRB 031220 : Kyoto Optical Observation
  53. GRB 031220: Subaru observation
  54. GRB 031220: Optical observation at Tokyo Tech
  55. GRB031220: ROTSE-IIIb Optical Limits
  56. GRB031220 : Optical Observation of Lulin Observatory
  57. GRB 031203 I-band monitoring
  58. IPN triangulation of GRB031214 (short/hard; very intense; small error box)
  59. GRB 2974 follow-up observations
  60. GRB031203, improved XMM position
  61. GRB 031203: Discovery of a dust echo
  62. GRB031214 triangulation (annulus), [repost of GCN2487, subject corrected]
  63. GRB030921 triangulation (annulus)
  64. GRB 031203: SMARTS optical monitoring
  65. GRB 021203: A Normal GRB viewed far off axis?
  66. XMM-Newton Observations of GRB031203: Preliminary Images
  67. GRB 031203: Variable Radio Source
  68. GRB 031203: Magellan spectrum of possible GRB host
  69. GRB 031203: Optical/IR Astrometry
  70. IPN/HETE localization of GRB031203B (=H2949; large error box)
  71. GRB031203 K prime photometry: correction to galaxy coordinates
  72. GRB031203: ROSAT upper limits suggest XMM-S1 source as the transient
  73. XMM-Newton Observation of GRB031203
  74. GRB 031203: Deep NIR NTT & VLT observations
  75. GRB031203: K' Photometry of the likely GRB host
  76. XMM-Newton Observation of GRB031203
  77. GRB 031203: Radio detection
  78. GRB 031203: Further reports on December 4 observations
  79. GRB 031203: IR NTTobservations do not confirm REM detection
  80. GRB031203 : Optical Observation of Lulin Observatory
  81. GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?
  82. GRB 031203: Apparent Spectral Break
  83. GRB031203: Planned XMM-Newton observation II
  84. GRB 031203: IR REM Observations
  85. GRB031203: Optical Observations
  86. GRB 031203 XMM-Newton observation
  87. GRB 031203: Optical/IR SMARTS Observations
  88. GRB031203: Planned XMM-Newton observation
  89. IPN triangulation of GRB031127A and B (quasi-simultaneous; large error boxes)
  90. GRB 031203: further analysis of INTEGRAL data
  91. GRB 031203: A long GRB detected with INTEGRAL
  92. IPN triangulation of GRB031201 (large error box)
  93. IPN triangulation of GRB031130 (large error box)
  94. GRB031111A, prompt optical observations
  95. GRB 030329: Planned XMM-Newton Observation
  96. IPN triangulation of GRB031120 (two large error boxes)
  97. GRB 031111B (= H2925) : Kyoto Optical Observation
  98. IPN/HETE localization of GRB031109 (=H2917; large error box)
  99. IPN detection of activity from SGR1806-20
  100. GRB 031111, Radio observations

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