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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. RXTE GRB040229 optical observation: no candidate
  2. GRB 040228 Optical observations
  3. IPN triangulation of GRB040228 (H3066, H3067)
  4. GRB040228 : KISO optical follow-up observation
  5. GRB 040228 (=H3066?,=H3067?): A Long GRB Localized by the HETE-2 WXM
  6. GRB 040223: Deep NIR NTT observations
  7. GRB 040223 : Optical observation (non-detection)
  8. XMM-Newton Images of GRB 040223
  9. GRB 040223, VLA observations
  10. GRB 040223: REM IJK Observations
  11. GRB 040223 XMM-Newton observation ...
  12. GRB 031203 XMM-Newton observation
  13. GRB 040223 : Planned XMM-Newton observation
  14. GRB 040106 : Planned XMM-Newton observation
  15. GRB 040223: further offline analysis
  16. GRB 040223: a long GRB detected with INTEGRAL
  17. GRB031111, optical observations
  18. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  19. GRB031203: Chandra Observations
  20. GRB040106, follow-up radio observations
  21. GRB040106: refined X-ray transient position
  22. Follow-up on IBAS GRB Alert 1379
  23. IBAS GRB alert 1379
  24. SN 2003dh/GRB030329 late-time optical spectroscopy
  25. GRB040106, Radio Observations
  26. GRB040106, likely optical afterglow
  27. GRB040106: Second Epoch Optical Observations
  28. GRB 031220: Optical observations of Chandra X-ray sources
  29. XMM-Newton Images of GRB 040106
  30. GRB040106: optical observations with REM+ROSS
  31. GRB031220: observation at Univercity of Miyazaki
  32. GRB 040106: Optical observations
  33. XMM-Newton observation of GRB040106
  34. GRB 040106 : Planned XMM-Newton observation
  35. GRB 040106 : peak flux
  36. GRB 040106 : a long GRB detected with INTEGRAL
  37. IPN triangulation of an intermediate burst from SGR1806-20
  38. GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
  39. GRB031220(=H2976): Observation with the Chandra X-ray Observatory
  40. GRB031225a triangulation (annulus)
  41. IPN triangulation of GRB031219 (large error box)
  42. GRB031220: Palomar Observations
  43. GRB 031220 : Kyoto Optical Observation
  44. GRB 031220: Subaru observation
  45. GRB 031220: Optical observation at Tokyo Tech
  46. GRB031220: ROTSE-IIIb Optical Limits
  47. GRB031220 : Optical Observation of Lulin Observatory
  48. GRB 031203 I-band monitoring
  49. IPN triangulation of GRB031214 (short/hard; very intense; small error box)
  50. GRB 2974 follow-up observations
  51. GRB031203, improved XMM position
  52. GRB 031203: Discovery of a dust echo
  53. GRB031214 triangulation (annulus), [repost of GCN2487, subject corrected]
  54. GRB030921 triangulation (annulus)
  55. GRB 031203: SMARTS optical monitoring
  56. GRB 021203: A Normal GRB viewed far off axis?
  57. XMM-Newton Observations of GRB031203: Preliminary Images
  58. GRB 031203: Variable Radio Source
  59. GRB 031203: Magellan spectrum of possible GRB host
  60. GRB 031203: Optical/IR Astrometry
  61. IPN/HETE localization of GRB031203B (=H2949; large error box)
  62. GRB031203 K prime photometry: correction to galaxy coordinates
  63. GRB031203: ROSAT upper limits suggest XMM-S1 source as the transient
  64. XMM-Newton Observation of GRB031203
  65. GRB 031203: Deep NIR NTT & VLT observations
  66. GRB031203: K' Photometry of the likely GRB host
  67. XMM-Newton Observation of GRB031203
  68. GRB 031203: Radio detection
  69. GRB 031203: Further reports on December 4 observations
  70. GRB 031203: IR NTTobservations do not confirm REM detection
  71. GRB031203 : Optical Observation of Lulin Observatory
  72. GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?
  73. GRB 031203: Apparent Spectral Break
  74. GRB031203: Planned XMM-Newton observation II
  75. GRB 031203: IR REM Observations
  76. GRB031203: Optical Observations
  77. GRB 031203 XMM-Newton observation
  78. GRB 031203: Optical/IR SMARTS Observations
  79. GRB031203: Planned XMM-Newton observation
  80. IPN triangulation of GRB031127A and B (quasi-simultaneous; large error boxes)
  81. GRB 031203: further analysis of INTEGRAL data
  82. GRB 031203: A long GRB detected with INTEGRAL
  83. IPN triangulation of GRB031201 (large error box)
  84. IPN triangulation of GRB031130 (large error box)
  85. GRB031111A, prompt optical observations
  86. GRB 030329: Planned XMM-Newton Observation
  87. IPN triangulation of GRB031120 (two large error boxes)
  88. GRB 031111B (= H2925) : Kyoto Optical Observation
  89. IPN/HETE localization of GRB031109 (=H2917; large error box)
  90. IPN detection of activity from SGR1806-20
  91. GRB 031111, Radio observations
  92. IPN triangulation of GRB031114 (large error box)
  93. IPN triangulation of GRB031107 (two large error boxes)
  94. GRB 031111: Optical observations
  95. GRB 031111, optical observations
  96. SN 2003jd (SN/GRB?) -- X-ray Observations
  97. HETE Prompt GRB Spectral Analyses
  98. IPN triangulation of GRB031111 (=H2924): small error box
  99. XRF031109 (=H2919): A very long XRF localized by HETE
  100. IPN triangulation of GRB031108 (large error box)

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