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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. GRB 040323: a long GRB detected with INTEGRAL
  2. IBAS GRB alerts 1679, 1680, 1681
  3. GRB040223: Deep NIR NTT data re-analysis
  4. GRB 040223: XMM-Newton results
  5. GRB040223, improved XMM position
  6. IBAS Alert 1678: not a GRB
  7. GRB 031203: spectoscopic evidence for a 1998bw-like SN
  8. GRB 031203, possible supernova
  9. MASTER: RXTE GRB040308 optical observation
  10. IBAS results on a burst from SGR1806-20
  11. INTEGRAL detection of activity from SGR1806-20
  12. RXTE GRB040229 optical observation: no candidate
  13. GRB 040228 Optical observations
  14. IPN triangulation of GRB040228 (H3066, H3067)
  15. GRB040228 : KISO optical follow-up observation
  16. GRB 040228 (=H3066?,=H3067?): A Long GRB Localized by the HETE-2 WXM
  17. GRB 040223: Deep NIR NTT observations
  18. GRB 040223 : Optical observation (non-detection)
  19. XMM-Newton Images of GRB 040223
  20. GRB 040223, VLA observations
  21. GRB 040223: REM IJK Observations
  22. GRB 040223 XMM-Newton observation ...
  23. GRB 031203 XMM-Newton observation
  24. GRB 040223 : Planned XMM-Newton observation
  25. GRB 040106 : Planned XMM-Newton observation
  26. GRB 040223: further offline analysis
  27. GRB 040223: a long GRB detected with INTEGRAL
  28. GRB031111, optical observations
  29. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  30. GRB031203: Chandra Observations
  31. GRB040106, follow-up radio observations
  32. GRB040106: refined X-ray transient position
  33. Follow-up on IBAS GRB Alert 1379
  34. IBAS GRB alert 1379
  35. SN 2003dh/GRB030329 late-time optical spectroscopy
  36. GRB040106, Radio Observations
  37. GRB040106, likely optical afterglow
  38. GRB040106: Second Epoch Optical Observations
  39. GRB 031220: Optical observations of Chandra X-ray sources
  40. XMM-Newton Images of GRB 040106
  41. GRB040106: optical observations with REM+ROSS
  42. GRB031220: observation at Univercity of Miyazaki
  43. GRB 040106: Optical observations
  44. XMM-Newton observation of GRB040106
  45. GRB 040106 : Planned XMM-Newton observation
  46. GRB 040106 : peak flux
  47. GRB 040106 : a long GRB detected with INTEGRAL
  48. IPN triangulation of an intermediate burst from SGR1806-20
  49. GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
  50. GRB031220(=H2976): Observation with the Chandra X-ray Observatory
  51. GRB031225a triangulation (annulus)
  52. IPN triangulation of GRB031219 (large error box)
  53. GRB031220: Palomar Observations
  54. GRB 031220 : Kyoto Optical Observation
  55. GRB 031220: Subaru observation
  56. GRB 031220: Optical observation at Tokyo Tech
  57. GRB031220: ROTSE-IIIb Optical Limits
  58. GRB031220 : Optical Observation of Lulin Observatory
  59. GRB 031203 I-band monitoring
  60. IPN triangulation of GRB031214 (short/hard; very intense; small error box)
  61. GRB 2974 follow-up observations
  62. GRB031203, improved XMM position
  63. GRB 031203: Discovery of a dust echo
  64. GRB031214 triangulation (annulus), [repost of GCN2487, subject corrected]
  65. GRB030921 triangulation (annulus)
  66. GRB 031203: SMARTS optical monitoring
  67. GRB 021203: A Normal GRB viewed far off axis?
  68. XMM-Newton Observations of GRB031203: Preliminary Images
  69. GRB 031203: Variable Radio Source
  70. GRB 031203: Magellan spectrum of possible GRB host
  71. GRB 031203: Optical/IR Astrometry
  72. IPN/HETE localization of GRB031203B (=H2949; large error box)
  73. GRB031203 K prime photometry: correction to galaxy coordinates
  74. GRB031203: ROSAT upper limits suggest XMM-S1 source as the transient
  75. XMM-Newton Observation of GRB031203
  76. GRB 031203: Deep NIR NTT & VLT observations
  77. GRB031203: K' Photometry of the likely GRB host
  78. XMM-Newton Observation of GRB031203
  79. GRB 031203: Radio detection
  80. GRB 031203: Further reports on December 4 observations
  81. GRB 031203: IR NTTobservations do not confirm REM detection
  82. GRB031203 : Optical Observation of Lulin Observatory
  83. GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?
  84. GRB 031203: Apparent Spectral Break
  85. GRB031203: Planned XMM-Newton observation II
  86. GRB 031203: IR REM Observations
  87. GRB031203: Optical Observations
  88. GRB 031203 XMM-Newton observation
  89. GRB 031203: Optical/IR SMARTS Observations
  90. GRB031203: Planned XMM-Newton observation
  91. IPN triangulation of GRB031127A and B (quasi-simultaneous; large error boxes)
  92. GRB 031203: further analysis of INTEGRAL data
  93. GRB 031203: A long GRB detected with INTEGRAL
  94. IPN triangulation of GRB031201 (large error box)
  95. IPN triangulation of GRB031130 (large error box)
  96. GRB031111A, prompt optical observations
  97. GRB 030329: Planned XMM-Newton Observation
  98. IPN triangulation of GRB031120 (two large error boxes)
  99. GRB 031111B (= H2925) : Kyoto Optical Observation
  100. IPN/HETE localization of GRB031109 (=H2917; large error box)

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