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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. IPN Upper Limits to a GRB Associated With SN2002ap
  2. GRB020124 BVRI field photometry
  3. GRB020127: Palomar and VLA Observations of Possible Counterparts
  4. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  5. SN2002ap (SN/GRB?) Echelle spectra
  6. SN2002ap (SN/GRB?) optical spectrographic observations
  7. GRB020127, WSRT radio observations
  8. GRB020127 Optical Observations
  9. SN 2002ap (SN/GRB?)
  10. SN 2002ap in M74
  11. SN2002ap (SN/GRB?) UBVRI Field Photometry
  12. GRB020127: Chandra Observations and Prospective Counterparts
  13. pre-SN2002ap (SN/GRB?) imaging of M74
  14. SN 2002ap (hypernova / GRB ??): special list on VSNET
  15. Type Ib/c SN2002ap (SN/GRB?)
  16. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  17. GRB020124, optical observations
  18. GRB020127: Optical observations
  19. GRB 020127, I-band observations starting 3.14-hr after the event
  20. IPN detection of further activity from SGR1806-20
  21. IPN triangulation of GRB020127 (=H1902)
  22. GRB020127 Optical Observations -- Erratum to GCN 1230
  23. GRB010921 Optical Observations
  24. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  25. GRB020124: Optical observations
  26. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  27. GRB020124: Optical observations
  28. GRB 020124: Optical observations
  29. GRB 020124 Optical Observations
  30. IPN triangulation of GRB020124 (HETE 1896)
  31. IPN observations of SGR1806-20
  32. GRB 020124: Optical afterglow
  33. GRB020124(=H1896): Localization of a Long GRB by HETE
  34. HETE 1896: Optical observations
  35. GRB optical counterpart candidate in GCN 1217 is M dwarf
  36. Possible optical counterpart to a GRB
  37. GRB011212, Optical Observations
  38. GRB011211: BeppoSAX/GRBM data
  39. Optical polarization observations for GRB011211
  40. GRB 011211: Detection of the Probable Host Galaxy
  41. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  42. Color indices of the afterglow of GRB011211
  43. GRB011212: Optical observations at Gunma
  44. GRB 011211, spectrum and optical photometry
  45. GRB 011130: Optical Observations of X-ray and Radio Sources
  46. GRB 011130, Radio/X-ray Comparison
  47. GRB011212: Optical observations
  48. GRB 011212: optical observation at Asiago
  49. GRB 011211: Evidence for an Optical Break
  50. GRB 011211: TNG Spectroscopic Observations
  51. optical follow-up of GRB(XRF) 011211
  52. GRB 011212: optical observation at Oslo (relayed)
  53. GRB 011211: Optical Spectroscopy
  54. GRB 011211, Optical Observations
  55. GRB011212, BVRI field photometry
  56. GRB011211, BVRI field photometry
  57. GRB011212: Optical observations
  58. GRB 011211: BVRi-band photometry
  59. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  60. Fading of the optical source associated of XRF 011211
  61. XMM-Newton observation of GRB011211
  62. GRB 011211 Optical Observations: Likely Afterglow
  63. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  64. GRB011211(=XRF011211): BeppoSAX refined positions
  65. BeppoSAX Alert: GRB011211(=XRF011211)
  66. GRB 011130: Optical Observations of Chandra Sources
  67. GRB 011130: Optical Observations of Chandra sources
  68. GRB011130 (XRF011130) Chandra Observations
  69. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  70. GRB 011130: Magellan spectroscopy
  71. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  72. GRB011130, optical observations
  73. GRB 011130, K band observations
  74. GRB011130, optical observations
  75. GRB011130 (=XRF011130): Second Revised Localization by HETE
  76. GRB 011130 I-band Observation
  77. GRB011130 (XRF011130) optical observations
  78. GRB011130 (XRF011130) SDSS PT i-band observations
  79. XRF011130: Infrared Observations
  80. GRB011130, Radio Observations
  81. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  82. GRB011130 (=XRF011130), Optical Observations
  83. XRF011130: NEAT Optical Observations
  84. GRB011130 (=XRF011130): Revised Localization of an X-ray
  85. GRB001109, Radio Monitoring
  86. GRB 011121: Errata URL
  87. GRB 011121
  88. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  89. GRB 011121: J-band observations
  90. GRB 011121: NIR observations, host galaxy?
  91. GRB010921 - Milagro GeV/TeV Observations
  92. GRB 011121: HST Scheduled
  93. GRB011121: fainter still
  94. Correction: GCN1157 (GRB 011121)
  95. GRB011121: UBRI Observations
  96. GRB011121
  97. GRB 011121: Radio Observations
  98. GRB 011121 J-Band Astrometry
  99. GRB011121: continued decay
  100. GRB 011121: Detection of Bright IR Counterpart

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