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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. GRB 020317: Optical observations
  2. GRB 011121: Third HST Epoch
  3. GRB020305: Properties of the Candidate Optical Afterglow
  4. GRB 011121: HST Observations reveal an intermediate-time multicolor
  5. GRB011121, possible supernova association
  6. GRB011130 (XRF011130) Second Epoch Chandra Observations
  7. GRB020305: Subaru Optical Observations
  8. GRB 020305: Optical observations
  9. XRF/GRB 011030 Images
  10. XRF/GRB 011030: Detection of the Probable Host Galaxy
  11. GRB 020305: Candidate optical afterglow
  12. Type Ic SN2002bl (SN/GRB?) Radio Observations
  13. GRB020305, optical observations
  14. GRB020305: Optical Observations
  15. IPN triangulation of GRB020305 (HETE 1939)
  16. GRB020305 (=H1939): Localization of a GRB by HETE
  17. GRB 020305: Optical observations
  18. HST Imaging of the afterglow and host of GRB 011121
  19. GRB 010921: HST Observations
  20. IPN detection and localization of Cygnus X-1 flares
  21. GRB020127: Further VLA Observations of Possible Counterparts
  22. RXTE Observations of SGR 1900+14
  23. IPN detection of further SGR1900+14 activity
  24. SGR1900+14 activity
  25. IPN/HETE Detection of Bursts from SGR1900+14
  26. IPN Upper Limits to a GRB Associated With SN2002ap
  27. GRB020124 BVRI field photometry
  28. GRB020127: Palomar and VLA Observations of Possible Counterparts
  29. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  30. SN2002ap (SN/GRB?) Echelle spectra
  31. SN2002ap (SN/GRB?) optical spectrographic observations
  32. GRB020127, WSRT radio observations
  33. GRB020127 Optical Observations
  34. SN 2002ap (SN/GRB?)
  35. SN 2002ap in M74
  36. SN2002ap (SN/GRB?) UBVRI Field Photometry
  37. GRB020127: Chandra Observations and Prospective Counterparts
  38. pre-SN2002ap (SN/GRB?) imaging of M74
  39. SN 2002ap (hypernova / GRB ??): special list on VSNET
  40. Type Ib/c SN2002ap (SN/GRB?)
  41. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  42. GRB020124, optical observations
  43. GRB020127: Optical observations
  44. GRB 020127, I-band observations starting 3.14-hr after the event
  45. IPN detection of further activity from SGR1806-20
  46. IPN triangulation of GRB020127 (=H1902)
  47. GRB020127 Optical Observations -- Erratum to GCN 1230
  48. GRB010921 Optical Observations
  49. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  50. GRB020124: Optical observations
  51. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  52. GRB020124: Optical observations
  53. GRB 020124: Optical observations
  54. GRB 020124 Optical Observations
  55. IPN triangulation of GRB020124 (HETE 1896)
  56. IPN observations of SGR1806-20
  57. GRB 020124: Optical afterglow
  58. GRB020124(=H1896): Localization of a Long GRB by HETE
  59. HETE 1896: Optical observations
  60. GRB optical counterpart candidate in GCN 1217 is M dwarf
  61. Possible optical counterpart to a GRB
  62. GRB011212, Optical Observations
  63. GRB011211: BeppoSAX/GRBM data
  64. Optical polarization observations for GRB011211
  65. GRB 011211: Detection of the Probable Host Galaxy
  66. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  67. Color indices of the afterglow of GRB011211
  68. GRB011212: Optical observations at Gunma
  69. GRB 011211, spectrum and optical photometry
  70. GRB 011130: Optical Observations of X-ray and Radio Sources
  71. GRB 011130, Radio/X-ray Comparison
  72. GRB011212: Optical observations
  73. GRB 011212: optical observation at Asiago
  74. GRB 011211: Evidence for an Optical Break
  75. GRB 011211: TNG Spectroscopic Observations
  76. optical follow-up of GRB(XRF) 011211
  77. GRB 011212: optical observation at Oslo (relayed)
  78. GRB 011211: Optical Spectroscopy
  79. GRB 011211, Optical Observations
  80. GRB011212, BVRI field photometry
  81. GRB011211, BVRI field photometry
  82. GRB011212: Optical observations
  83. GRB 011211: BVRi-band photometry
  84. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  85. Fading of the optical source associated of XRF 011211
  86. XMM-Newton observation of GRB011211
  87. GRB 011211 Optical Observations: Likely Afterglow
  88. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  89. GRB011211(=XRF011211): BeppoSAX refined positions
  90. BeppoSAX Alert: GRB011211(=XRF011211)
  91. GRB 011130: Optical Observations of Chandra Sources
  92. GRB 011130: Optical Observations of Chandra sources
  93. GRB011130 (XRF011130) Chandra Observations
  94. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  95. GRB 011130: Magellan spectroscopy
  96. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  97. GRB011130, optical observations
  98. GRB 011130, K band observations
  99. GRB011130, optical observations
  100. GRB011130 (=XRF011130): Second Revised Localization by HETE

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