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

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