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

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