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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. GRB020322: BeppoSAX/NFI Observations
  2. Bepposax GRB020322 The second springtime BSAX GRB
  3. GRB 020321: Optical observations
  4. GRB 011121: Fourth Epoch of HST Imaging
  5. GRB020317: optical observations
  6. GRB020321 optical observations
  7. GRB020321: BeppoSAX/NFI Observations
  8. GRB020321: a faint BeppoSAX detection
  9. GRB020305: NIR observations
  10. GRB 020317 : KISO Optical Observations
  11. BeppoSAX ALERT: GRB020321, the "Springtime Burst"
  12. GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
  13. GRB 020305: Optical Observations
  14. GRB020317, optical observations
  15. GRB 020317: Optical observations
  16. GRB 011121: Third HST Epoch
  17. GRB020305: Properties of the Candidate Optical Afterglow
  18. GRB 011121: HST Observations reveal an intermediate-time multicolor
  19. GRB011121, possible supernova association
  20. GRB011130 (XRF011130) Second Epoch Chandra Observations
  21. GRB020305: Subaru Optical Observations
  22. GRB 020305: Optical observations
  23. XRF/GRB 011030 Images
  24. XRF/GRB 011030: Detection of the Probable Host Galaxy
  25. GRB 020305: Candidate optical afterglow
  26. Type Ic SN2002bl (SN/GRB?) Radio Observations
  27. GRB020305, optical observations
  28. GRB020305: Optical Observations
  29. IPN triangulation of GRB020305 (HETE 1939)
  30. GRB020305 (=H1939): Localization of a GRB by HETE
  31. GRB 020305: Optical observations
  32. HST Imaging of the afterglow and host of GRB 011121
  33. GRB 010921: HST Observations
  34. IPN detection and localization of Cygnus X-1 flares
  35. GRB020127: Further VLA Observations of Possible Counterparts
  36. RXTE Observations of SGR 1900+14
  37. IPN detection of further SGR1900+14 activity
  38. SGR1900+14 activity
  39. IPN/HETE Detection of Bursts from SGR1900+14
  40. IPN Upper Limits to a GRB Associated With SN2002ap
  41. GRB020124 BVRI field photometry
  42. GRB020127: Palomar and VLA Observations of Possible Counterparts
  43. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  44. SN2002ap (SN/GRB?) Echelle spectra
  45. SN2002ap (SN/GRB?) optical spectrographic observations
  46. GRB020127, WSRT radio observations
  47. GRB020127 Optical Observations
  48. SN 2002ap (SN/GRB?)
  49. SN 2002ap in M74
  50. SN2002ap (SN/GRB?) UBVRI Field Photometry
  51. GRB020127: Chandra Observations and Prospective Counterparts
  52. pre-SN2002ap (SN/GRB?) imaging of M74
  53. SN 2002ap (hypernova / GRB ??): special list on VSNET
  54. Type Ib/c SN2002ap (SN/GRB?)
  55. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  56. GRB020124, optical observations
  57. GRB020127: Optical observations
  58. GRB 020127, I-band observations starting 3.14-hr after the event
  59. IPN detection of further activity from SGR1806-20
  60. IPN triangulation of GRB020127 (=H1902)
  61. GRB020127 Optical Observations -- Erratum to GCN 1230
  62. GRB010921 Optical Observations
  63. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  64. GRB020124: Optical observations
  65. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  66. GRB020124: Optical observations
  67. GRB 020124: Optical observations
  68. GRB 020124 Optical Observations
  69. IPN triangulation of GRB020124 (HETE 1896)
  70. IPN observations of SGR1806-20
  71. GRB 020124: Optical afterglow
  72. GRB020124(=H1896): Localization of a Long GRB by HETE
  73. HETE 1896: Optical observations
  74. GRB optical counterpart candidate in GCN 1217 is M dwarf
  75. Possible optical counterpart to a GRB
  76. GRB011212, Optical Observations
  77. GRB011211: BeppoSAX/GRBM data
  78. Optical polarization observations for GRB011211
  79. GRB 011211: Detection of the Probable Host Galaxy
  80. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  81. Color indices of the afterglow of GRB011211
  82. GRB011212: Optical observations at Gunma
  83. GRB 011211, spectrum and optical photometry
  84. GRB 011130: Optical Observations of X-ray and Radio Sources
  85. GRB 011130, Radio/X-ray Comparison
  86. GRB011212: Optical observations
  87. GRB 011212: optical observation at Asiago
  88. GRB 011211: Evidence for an Optical Break
  89. GRB 011211: TNG Spectroscopic Observations
  90. optical follow-up of GRB(XRF) 011211
  91. GRB 011212: optical observation at Oslo (relayed)
  92. GRB 011211: Optical Spectroscopy
  93. GRB 011211, Optical Observations
  94. GRB011212, BVRI field photometry
  95. GRB011211, BVRI field photometry
  96. GRB011212: Optical observations
  97. GRB 011211: BVRi-band photometry
  98. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  99. Fading of the optical source associated of XRF 011211
  100. XMM-Newton observation of GRB011211

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