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

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