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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 070328 : Suzaku ToO follow up starts
  2. GRB 070328, Swift-BAT refined analysis
  3. GRB 070328: Swift detection of a burst
  4. GRB070220: optical observations
  5. GRB070208: optical observations
  6. GRB070223: confirmation of nIR and optical afterglow
  7. GRB070318: Swift UVOT indicates unusual optical/UV afterglow
  8. GRB 070311, deep optical photometry
  9. Short-Hard GRB 070209: PROMPT Observations
  10. GRB 070318: Gemini + Magellan spectra
  11. GRB 070318: absorption-line redshift
  12. GRB070318: Swift UVOT continuing observations
  13. GRB070318: Swift-XRT refined analysis
  14. GRB 070318: Swift/UVOT Continued Observations
  15. GRB 070318, Swift-BAT refined analysis
  16. IBAS Alert n. 4176: not a GRB
  17. GRB 070318: Swift detection of a burst with an optical afterglow
  18. GRB 070311: Late Central Engine Activity Optical Flare??
  19. GRB 070311: MDM Optical Monitoring
  20. VLA observation of GRB 070311
  21. GRB 070311: Tautenburg sees afterglow fading
  22. IBAS Alert n. 4169: not a GRB
  23. GRB 070311: Optical observation.
  24. GRB 070311: Optical Brightening
  25. GRB 070306: possible emission-line redshift
  26. GRB 070311: SARA upper limit
  27. GRB 070309: variability of the XRT afterglow candidate
  28. GRB 070311: MDM Optical Follow-up
  29. GRB 070311: RAPTOR Detection of Optical Emission
  30. GRB070311: FRAM early follow-up limit
  31. GRB 070311: P60 Observations
  32. GRB 070311: MDM Optical Detection
  33. GRB 070311: Swift/UVOT Upper Limits
  34. GRB 070311: MITSuME Okayama Optical Observation
  35. GRB 070311: Swift-XRT refined analysis
  36. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  37. GRB 070311: REM candidate afterglow
  38. GRB 070311: a long GRB detected by INTEGRAL
  39. GRB060901: Candidate optical afterglow
  40. GRB070309: Swift/XRT possible afterglow detection
  41. GRB 070125: Chandra X-ray Confirmation of Jet Break
  42. GRB 070309: Swift/UVOT Upper Limits
  43. GRB 070306, optical observation
  44. Swift UVOT Finding Charts for GRB 070309
  45. GRB 070309: A long GRB detected by INTEGRAL
  46. GRB 070125: X-ray light curve analysis
  47. VLA observation of GRB 070306
  48. IBAS Alert 4162: Not a GRB
  49. GRB 070306: NOT observations
  50. GRB 070306 Swift/UVOT refined analysis
  51. GRB070306: confirmation of near infrared afterglow
  52. GRB 070306: ART-3 early optical and near infrared constraints
  53. GRB 070306: IR observations and candidate afterglow
  54. GRB 070306, Swift-BAT refined analysis
  55. GRB 070306: XRT Team Refined Analysis
  56. GRB 070306: Optical and IR observations with KANATA
  57. GRB070306 - SDSS Pre-burst Observations
  58. GRB 070306: Swift detection of a burst
  59. GRB 070223: NIR observations at WHT
  60. GRB070227: Swift-XRT refined analysis
  61. GRB 060605 new redshift
  62. GRB 070125, deep late-time optical observation
  63. VLA observation of GRB 070224
  64. GRB 070227: optical observations
  65. GRB 070223: Optical Observations
  66. GRB 070227: optical observations
  67. GRB 070227: Swift/UVOT Upper Limits
  68. GRB 070227: TAROT La Silla observatory optical observations
  69. GRB 070227, Swift-BAT refined analysis
  70. GRB070227: possible X-ray afterglow detection
  71. GRB 070227: Swift detection of a burst in ground analysis
  72. GRB 920925C: optical afterglow candidate
  73. GRB 070224: Optical afterglow confirmation
  74. IBAS Alert n. 4144: not a GRB
  75. GRB 070224: Swift/UVOT Upper Limits
  76. GRB070224: Swift-XRT Astrometrically Corrected Position
  77. VLA observation of GRB 070223
  78. VLA observation of GRB 070220
  79. GRB070224: Magellan Imaging Observations
  80. GRB 070224: WHT K-band imaging
  81. GRB 070224: MDM Observations
  82. GRB070224: Gemini Imaging Observations
  83. GRB 070224: SARA upper limit
  84. GRB070224: Swift-XRT Refined Analysis
  85. GRB 070224: optical afterglow candidate
  86. GRB 070224, Swift-BAT refined analysis
  87. GRB 070224: MASTER-Net refind analysis
  88. GRB 070224: MASTER-VWF-Kislovodsk observations
  89. GRB 070224: MASTER observations
  90. GRB 070224: Swift detection of a burst
  91. GRB 070223: Optical observations
  92. RHESSI Spectrum of GRB070220
  93. GRB070223: Swift/UVOT refined analysis
  94. GRB 070223: Optical-IR observation with KANATA
  95. GRB 070223, Swift-BAT refined analysis
  96. GRB070223: MASTER-VWF-Kislovodsk observations
  97. GRB 070223: Swift-XRT Refined Analysis
  98. GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
  99. GRB070223 - SDSS Pre-Burst Observations
  100. GRB 070223: Liverpool Telescope Possible Afterglow Candidate

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