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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 070406: Xinglong TNT optical Upper Limit
  2. GRB 070406: photo-z of a bright galaxy in BAT error circle
  3. GRB 070406: Swift detection of a burst
  4. GRB 070402: Suzaku WAM observation of the prompt emission
  5. GRB 070311, deep optical photometry
  6. GRB 070402: pseudo-z~3.36 from spectral parameters of the prompt
  7. Konus-Wind and Konus-A observations of GRB 070402
  8. IPN triangulation of GRB070402 - correction
  9. IPN triangulation of GRB070402
  10. GRB 070328: Suzaku WAM observation of the prompt emission
  11. INTEGRAL ToO Observation of SGR1806-20
  12. UVOT observations of GRB070330
  13. GRB 070330, Swift-BAT refined analysis
  14. GRB 070330, SMARTS optical/IR observations
  15. GRB 070330: TAROT La Silla observatory optical observations
  16. GRB 070330: Swift-XRT refined analysis
  17. GRB 070330 - Watcher Observations
  18. GRB 070330: Swift detection of a burst
  19. GRB 070328: pseudo-z~2.75 from spectral parameters of the prompt
  20. Konus-Wind observation of GRB 070328
  21. GRB 070328: Swift/UVOT Upper Limits
  22. long burst from SGR 1806-20 detected on March 26
  23. GRB 070328: Swift/XRT Refined Analysis
  24. GRB 070328 : Suzaku ToO follow up starts
  25. GRB 070328, Swift-BAT refined analysis
  26. GRB 070328: Swift detection of a burst
  27. GRB070220: optical observations
  28. GRB070208: optical observations
  29. GRB070223: confirmation of nIR and optical afterglow
  30. GRB070318: Swift UVOT indicates unusual optical/UV afterglow
  31. GRB 070311, deep optical photometry
  32. Short-Hard GRB 070209: PROMPT Observations
  33. GRB 070318: Gemini + Magellan spectra
  34. GRB 070318: absorption-line redshift
  35. GRB070318: Swift UVOT continuing observations
  36. GRB070318: Swift-XRT refined analysis
  37. GRB 070318: Swift/UVOT Continued Observations
  38. GRB 070318, Swift-BAT refined analysis
  39. IBAS Alert n. 4176: not a GRB
  40. GRB 070318: Swift detection of a burst with an optical afterglow
  41. GRB 070311: Late Central Engine Activity Optical Flare??
  42. GRB 070311: MDM Optical Monitoring
  43. VLA observation of GRB 070311
  44. GRB 070311: Tautenburg sees afterglow fading
  45. IBAS Alert n. 4169: not a GRB
  46. GRB 070311: Optical observation.
  47. GRB 070311: Optical Brightening
  48. GRB 070306: possible emission-line redshift
  49. GRB 070311: SARA upper limit
  50. GRB 070309: variability of the XRT afterglow candidate
  51. GRB 070311: MDM Optical Follow-up
  52. GRB 070311: RAPTOR Detection of Optical Emission
  53. GRB070311: FRAM early follow-up limit
  54. GRB 070311: P60 Observations
  55. GRB 070311: MDM Optical Detection
  56. GRB 070311: Swift/UVOT Upper Limits
  57. GRB 070311: MITSuME Okayama Optical Observation
  58. GRB 070311: Swift-XRT refined analysis
  59. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  60. GRB 070311: REM candidate afterglow
  61. GRB 070311: a long GRB detected by INTEGRAL
  62. GRB060901: Candidate optical afterglow
  63. GRB070309: Swift/XRT possible afterglow detection
  64. GRB 070125: Chandra X-ray Confirmation of Jet Break
  65. GRB 070309: Swift/UVOT Upper Limits
  66. GRB 070306, optical observation
  67. Swift UVOT Finding Charts for GRB 070309
  68. GRB 070309: A long GRB detected by INTEGRAL
  69. GRB 070125: X-ray light curve analysis
  70. VLA observation of GRB 070306
  71. IBAS Alert 4162: Not a GRB
  72. GRB 070306: NOT observations
  73. GRB 070306 Swift/UVOT refined analysis
  74. GRB070306: confirmation of near infrared afterglow
  75. GRB 070306: ART-3 early optical and near infrared constraints
  76. GRB 070306: IR observations and candidate afterglow
  77. GRB 070306, Swift-BAT refined analysis
  78. GRB 070306: XRT Team Refined Analysis
  79. GRB 070306: Optical and IR observations with KANATA
  80. GRB070306 - SDSS Pre-burst Observations
  81. GRB 070306: Swift detection of a burst
  82. GRB 070223: NIR observations at WHT
  83. GRB070227: Swift-XRT refined analysis
  84. GRB 060605 new redshift
  85. GRB 070125, deep late-time optical observation
  86. VLA observation of GRB 070224
  87. GRB 070227: optical observations
  88. GRB 070223: Optical Observations
  89. GRB 070227: optical observations
  90. GRB 070227: Swift/UVOT Upper Limits
  91. GRB 070227: TAROT La Silla observatory optical observations
  92. GRB 070227, Swift-BAT refined analysis
  93. GRB070227: possible X-ray afterglow detection
  94. GRB 070227: Swift detection of a burst in ground analysis
  95. GRB 920925C: optical afterglow candidate
  96. GRB 070224: Optical afterglow confirmation
  97. IBAS Alert n. 4144: not a GRB
  98. GRB 070224: Swift/UVOT Upper Limits
  99. GRB070224: Swift-XRT Astrometrically Corrected Position
  100. VLA observation of GRB 070223

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