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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 triangulation of GRB020305 (HETE 1939)
  2. GRB020305 (=H1939): Localization of a GRB by HETE
  3. GRB 020305: Optical observations
  4. HST Imaging of the afterglow and host of GRB 011121
  5. GRB 010921: HST Observations
  6. IPN detection and localization of Cygnus X-1 flares
  7. GRB020127: Further VLA Observations of Possible Counterparts
  8. RXTE Observations of SGR 1900+14
  9. IPN detection of further SGR1900+14 activity
  10. SGR1900+14 activity
  11. IPN/HETE Detection of Bursts from SGR1900+14
  12. IPN Upper Limits to a GRB Associated With SN2002ap
  13. GRB020124 BVRI field photometry
  14. GRB020127: Palomar and VLA Observations of Possible Counterparts
  15. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  16. SN2002ap (SN/GRB?) Echelle spectra
  17. SN2002ap (SN/GRB?) optical spectrographic observations
  18. GRB020127, WSRT radio observations
  19. GRB020127 Optical Observations
  20. SN 2002ap (SN/GRB?)
  21. SN 2002ap in M74
  22. SN2002ap (SN/GRB?) UBVRI Field Photometry
  23. GRB020127: Chandra Observations and Prospective Counterparts
  24. pre-SN2002ap (SN/GRB?) imaging of M74
  25. SN 2002ap (hypernova / GRB ??): special list on VSNET
  26. Type Ib/c SN2002ap (SN/GRB?)
  27. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  28. GRB020124, optical observations
  29. GRB020127: Optical observations
  30. GRB 020127, I-band observations starting 3.14-hr after the event
  31. IPN detection of further activity from SGR1806-20
  32. IPN triangulation of GRB020127 (=H1902)
  33. GRB020127 Optical Observations -- Erratum to GCN 1230
  34. GRB010921 Optical Observations
  35. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  36. GRB020124: Optical observations
  37. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  38. GRB020124: Optical observations
  39. GRB 020124: Optical observations
  40. GRB 020124 Optical Observations
  41. IPN triangulation of GRB020124 (HETE 1896)
  42. IPN observations of SGR1806-20
  43. GRB 020124: Optical afterglow
  44. GRB020124(=H1896): Localization of a Long GRB by HETE
  45. HETE 1896: Optical observations
  46. GRB optical counterpart candidate in GCN 1217 is M dwarf
  47. Possible optical counterpart to a GRB
  48. GRB011212, Optical Observations
  49. GRB011211: BeppoSAX/GRBM data
  50. Optical polarization observations for GRB011211
  51. GRB 011211: Detection of the Probable Host Galaxy
  52. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  53. Color indices of the afterglow of GRB011211
  54. GRB011212: Optical observations at Gunma
  55. GRB 011211, spectrum and optical photometry
  56. GRB 011130: Optical Observations of X-ray and Radio Sources
  57. GRB 011130, Radio/X-ray Comparison
  58. GRB011212: Optical observations
  59. GRB 011212: optical observation at Asiago
  60. GRB 011211: Evidence for an Optical Break
  61. GRB 011211: TNG Spectroscopic Observations
  62. optical follow-up of GRB(XRF) 011211
  63. GRB 011212: optical observation at Oslo (relayed)
  64. GRB 011211: Optical Spectroscopy
  65. GRB 011211, Optical Observations
  66. GRB011212, BVRI field photometry
  67. GRB011211, BVRI field photometry
  68. GRB011212: Optical observations
  69. GRB 011211: BVRi-band photometry
  70. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  71. Fading of the optical source associated of XRF 011211
  72. XMM-Newton observation of GRB011211
  73. GRB 011211 Optical Observations: Likely Afterglow
  74. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  75. GRB011211(=XRF011211): BeppoSAX refined positions
  76. BeppoSAX Alert: GRB011211(=XRF011211)
  77. GRB 011130: Optical Observations of Chandra Sources
  78. GRB 011130: Optical Observations of Chandra sources
  79. GRB011130 (XRF011130) Chandra Observations
  80. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  81. GRB 011130: Magellan spectroscopy
  82. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  83. GRB011130, optical observations
  84. GRB 011130, K band observations
  85. GRB011130, optical observations
  86. GRB011130 (=XRF011130): Second Revised Localization by HETE
  87. GRB 011130 I-band Observation
  88. GRB011130 (XRF011130) optical observations
  89. GRB011130 (XRF011130) SDSS PT i-band observations
  90. XRF011130: Infrared Observations
  91. GRB011130, Radio Observations
  92. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  93. GRB011130 (=XRF011130), Optical Observations
  94. XRF011130: NEAT Optical Observations
  95. GRB011130 (=XRF011130): Revised Localization of an X-ray
  96. GRB001109, Radio Monitoring
  97. GRB 011121: Errata URL
  98. GRB 011121
  99. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  100. GRB 011121: J-band observations

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