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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. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  2. GRB020124, optical observations
  3. GRB020127: Optical observations
  4. GRB 020127, I-band observations starting 3.14-hr after the event
  5. IPN detection of further activity from SGR1806-20
  6. IPN triangulation of GRB020127 (=H1902)
  7. GRB020127 Optical Observations -- Erratum to GCN 1230
  8. GRB010921 Optical Observations
  9. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  10. GRB020124: Optical observations
  11. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  12. GRB020124: Optical observations
  13. GRB 020124: Optical observations
  14. GRB 020124 Optical Observations
  15. IPN triangulation of GRB020124 (HETE 1896)
  16. IPN observations of SGR1806-20
  17. GRB 020124: Optical afterglow
  18. GRB020124(=H1896): Localization of a Long GRB by HETE
  19. HETE 1896: Optical observations
  20. GRB optical counterpart candidate in GCN 1217 is M dwarf
  21. Possible optical counterpart to a GRB
  22. GRB011212, Optical Observations
  23. GRB011211: BeppoSAX/GRBM data
  24. Optical polarization observations for GRB011211
  25. GRB 011211: Detection of the Probable Host Galaxy
  26. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  27. Color indices of the afterglow of GRB011211
  28. GRB011212: Optical observations at Gunma
  29. GRB 011211, spectrum and optical photometry
  30. GRB 011130: Optical Observations of X-ray and Radio Sources
  31. GRB 011130, Radio/X-ray Comparison
  32. GRB011212: Optical observations
  33. GRB 011212: optical observation at Asiago
  34. GRB 011211: Evidence for an Optical Break
  35. GRB 011211: TNG Spectroscopic Observations
  36. optical follow-up of GRB(XRF) 011211
  37. GRB 011212: optical observation at Oslo (relayed)
  38. GRB 011211: Optical Spectroscopy
  39. GRB 011211, Optical Observations
  40. GRB011212, BVRI field photometry
  41. GRB011211, BVRI field photometry
  42. GRB011212: Optical observations
  43. GRB 011211: BVRi-band photometry
  44. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  45. Fading of the optical source associated of XRF 011211
  46. XMM-Newton observation of GRB011211
  47. GRB 011211 Optical Observations: Likely Afterglow
  48. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  49. GRB011211(=XRF011211): BeppoSAX refined positions
  50. BeppoSAX Alert: GRB011211(=XRF011211)
  51. GRB 011130: Optical Observations of Chandra Sources
  52. GRB 011130: Optical Observations of Chandra sources
  53. GRB011130 (XRF011130) Chandra Observations
  54. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  55. GRB 011130: Magellan spectroscopy
  56. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  57. GRB011130, optical observations
  58. GRB 011130, K band observations
  59. GRB011130, optical observations
  60. GRB011130 (=XRF011130): Second Revised Localization by HETE
  61. GRB 011130 I-band Observation
  62. GRB011130 (XRF011130) optical observations
  63. GRB011130 (XRF011130) SDSS PT i-band observations
  64. XRF011130: Infrared Observations
  65. GRB011130, Radio Observations
  66. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  67. GRB011130 (=XRF011130), Optical Observations
  68. XRF011130: NEAT Optical Observations
  69. GRB011130 (=XRF011130): Revised Localization of an X-ray
  70. GRB001109, Radio Monitoring
  71. GRB 011121: Errata URL
  72. GRB 011121
  73. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  74. GRB 011121: J-band observations
  75. GRB 011121: NIR observations, host galaxy?
  76. GRB010921 - Milagro GeV/TeV Observations
  77. GRB 011121: HST Scheduled
  78. GRB011121: fainter still
  79. Correction: GCN1157 (GRB 011121)
  80. GRB011121: UBRI Observations
  81. GRB011121
  82. GRB 011121: Radio Observations
  83. GRB 011121 J-Band Astrometry
  84. GRB011121: continued decay
  85. GRB 011121: Detection of Bright IR Counterpart
  86. GRB011121: possible redshift, continued decay
  87. GRB011121: fading behavior
  88. GRB011121: possible optical counterpart
  89. GRB011121: BeppoSAX-WFC refined positions
  90. IPN triangulation of GRB011121
  91. BEPPOSAX GRB011121
  92. GRB 011030: TNG K-band observation
  93. XRF011030: J and K band observations
  94. GRB011030, optical observation
  95. XRF011030: Chandra Observations
  96. GRB 011030: K-band observations
  97. GRB011030: Z-band observations
  98. GRB 011030 R band observations
  99. GRB 011030 I-band Observation
  100. The X-ray Flash 011030 ('GRB 011030')

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