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

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