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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: Swift detection of a burst
  2. GRB 070402: Suzaku WAM observation of the prompt emission
  3. GRB 070311, deep optical photometry
  4. GRB 070402: pseudo-z~3.36 from spectral parameters of the prompt
  5. Konus-Wind and Konus-A observations of GRB 070402
  6. IPN triangulation of GRB070402 - correction
  7. IPN triangulation of GRB070402
  8. GRB 070328: Suzaku WAM observation of the prompt emission
  9. INTEGRAL ToO Observation of SGR1806-20
  10. UVOT observations of GRB070330
  11. GRB 070330, Swift-BAT refined analysis
  12. GRB 070330, SMARTS optical/IR observations
  13. GRB 070330: TAROT La Silla observatory optical observations
  14. GRB 070330: Swift-XRT refined analysis
  15. GRB 070330 - Watcher Observations
  16. GRB 070330: Swift detection of a burst
  17. GRB 070328: pseudo-z~2.75 from spectral parameters of the prompt
  18. Konus-Wind observation of GRB 070328
  19. GRB 070328: Swift/UVOT Upper Limits
  20. long burst from SGR 1806-20 detected on March 26
  21. GRB 070328: Swift/XRT Refined Analysis
  22. GRB 070328 : Suzaku ToO follow up starts
  23. GRB 070328, Swift-BAT refined analysis
  24. GRB 070328: Swift detection of a burst
  25. GRB070220: optical observations
  26. GRB070208: optical observations
  27. GRB070223: confirmation of nIR and optical afterglow
  28. GRB070318: Swift UVOT indicates unusual optical/UV afterglow
  29. GRB 070311, deep optical photometry
  30. Short-Hard GRB 070209: PROMPT Observations
  31. GRB 070318: Gemini + Magellan spectra
  32. GRB 070318: absorption-line redshift
  33. GRB070318: Swift UVOT continuing observations
  34. GRB070318: Swift-XRT refined analysis
  35. GRB 070318: Swift/UVOT Continued Observations
  36. GRB 070318, Swift-BAT refined analysis
  37. IBAS Alert n. 4176: not a GRB
  38. GRB 070318: Swift detection of a burst with an optical afterglow
  39. GRB 070311: Late Central Engine Activity Optical Flare??
  40. GRB 070311: MDM Optical Monitoring
  41. VLA observation of GRB 070311
  42. GRB 070311: Tautenburg sees afterglow fading
  43. IBAS Alert n. 4169: not a GRB
  44. GRB 070311: Optical observation.
  45. GRB 070311: Optical Brightening
  46. GRB 070306: possible emission-line redshift
  47. GRB 070311: SARA upper limit
  48. GRB 070309: variability of the XRT afterglow candidate
  49. GRB 070311: MDM Optical Follow-up
  50. GRB 070311: RAPTOR Detection of Optical Emission
  51. GRB070311: FRAM early follow-up limit
  52. GRB 070311: P60 Observations
  53. GRB 070311: MDM Optical Detection
  54. GRB 070311: Swift/UVOT Upper Limits
  55. GRB 070311: MITSuME Okayama Optical Observation
  56. GRB 070311: Swift-XRT refined analysis
  57. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  58. GRB 070311: REM candidate afterglow
  59. GRB 070311: a long GRB detected by INTEGRAL
  60. GRB060901: Candidate optical afterglow
  61. GRB070309: Swift/XRT possible afterglow detection
  62. GRB 070125: Chandra X-ray Confirmation of Jet Break
  63. GRB 070309: Swift/UVOT Upper Limits
  64. GRB 070306, optical observation
  65. Swift UVOT Finding Charts for GRB 070309
  66. GRB 070309: A long GRB detected by INTEGRAL
  67. GRB 070125: X-ray light curve analysis
  68. VLA observation of GRB 070306
  69. IBAS Alert 4162: Not a GRB
  70. GRB 070306: NOT observations
  71. GRB 070306 Swift/UVOT refined analysis
  72. GRB070306: confirmation of near infrared afterglow
  73. GRB 070306: ART-3 early optical and near infrared constraints
  74. GRB 070306: IR observations and candidate afterglow
  75. GRB 070306, Swift-BAT refined analysis
  76. GRB 070306: XRT Team Refined Analysis
  77. GRB 070306: Optical and IR observations with KANATA
  78. GRB070306 - SDSS Pre-burst Observations
  79. GRB 070306: Swift detection of a burst
  80. GRB 070223: NIR observations at WHT
  81. GRB070227: Swift-XRT refined analysis
  82. GRB 060605 new redshift
  83. GRB 070125, deep late-time optical observation
  84. VLA observation of GRB 070224
  85. GRB 070227: optical observations
  86. GRB 070223: Optical Observations
  87. GRB 070227: optical observations
  88. GRB 070227: Swift/UVOT Upper Limits
  89. GRB 070227: TAROT La Silla observatory optical observations
  90. GRB 070227, Swift-BAT refined analysis
  91. GRB070227: possible X-ray afterglow detection
  92. GRB 070227: Swift detection of a burst in ground analysis
  93. GRB 920925C: optical afterglow candidate
  94. GRB 070224: Optical afterglow confirmation
  95. IBAS Alert n. 4144: not a GRB
  96. GRB 070224: Swift/UVOT Upper Limits
  97. GRB070224: Swift-XRT Astrometrically Corrected Position
  98. VLA observation of GRB 070223
  99. VLA observation of GRB 070220
  100. GRB070224: Magellan Imaging Observations

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