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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. IBAS Alert n. 4176: not a GRB
  2. GRB 070318: Swift detection of a burst with an optical afterglow
  3. GRB 070311: Late Central Engine Activity Optical Flare??
  4. GRB 070311: MDM Optical Monitoring
  5. VLA observation of GRB 070311
  6. GRB 070311: Tautenburg sees afterglow fading
  7. IBAS Alert n. 4169: not a GRB
  8. GRB 070311: Optical observation.
  9. GRB 070311: Optical Brightening
  10. GRB 070306: possible emission-line redshift
  11. GRB 070311: SARA upper limit
  12. GRB 070309: variability of the XRT afterglow candidate
  13. GRB 070311: MDM Optical Follow-up
  14. GRB 070311: RAPTOR Detection of Optical Emission
  15. GRB070311: FRAM early follow-up limit
  16. GRB 070311: P60 Observations
  17. GRB 070311: MDM Optical Detection
  18. GRB 070311: Swift/UVOT Upper Limits
  19. GRB 070311: MITSuME Okayama Optical Observation
  20. GRB 070311: Swift-XRT refined analysis
  21. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  22. GRB 070311: REM candidate afterglow
  23. GRB 070311: a long GRB detected by INTEGRAL
  24. GRB060901: Candidate optical afterglow
  25. GRB070309: Swift/XRT possible afterglow detection
  26. GRB 070125: Chandra X-ray Confirmation of Jet Break
  27. GRB 070309: Swift/UVOT Upper Limits
  28. GRB 070306, optical observation
  29. Swift UVOT Finding Charts for GRB 070309
  30. GRB 070309: A long GRB detected by INTEGRAL
  31. GRB 070125: X-ray light curve analysis
  32. VLA observation of GRB 070306
  33. IBAS Alert 4162: Not a GRB
  34. GRB 070306: NOT observations
  35. GRB 070306 Swift/UVOT refined analysis
  36. GRB070306: confirmation of near infrared afterglow
  37. GRB 070306: ART-3 early optical and near infrared constraints
  38. GRB 070306: IR observations and candidate afterglow
  39. GRB 070306, Swift-BAT refined analysis
  40. GRB 070306: XRT Team Refined Analysis
  41. GRB 070306: Optical and IR observations with KANATA
  42. GRB070306 - SDSS Pre-burst Observations
  43. GRB 070306: Swift detection of a burst
  44. GRB 070223: NIR observations at WHT
  45. GRB070227: Swift-XRT refined analysis
  46. GRB 060605 new redshift
  47. GRB 070125, deep late-time optical observation
  48. VLA observation of GRB 070224
  49. GRB 070227: optical observations
  50. GRB 070223: Optical Observations
  51. GRB 070227: optical observations
  52. GRB 070227: Swift/UVOT Upper Limits
  53. GRB 070227: TAROT La Silla observatory optical observations
  54. GRB 070227, Swift-BAT refined analysis
  55. GRB070227: possible X-ray afterglow detection
  56. GRB 070227: Swift detection of a burst in ground analysis
  57. GRB 920925C: optical afterglow candidate
  58. GRB 070224: Optical afterglow confirmation
  59. IBAS Alert n. 4144: not a GRB
  60. GRB 070224: Swift/UVOT Upper Limits
  61. GRB070224: Swift-XRT Astrometrically Corrected Position
  62. VLA observation of GRB 070223
  63. VLA observation of GRB 070220
  64. GRB070224: Magellan Imaging Observations
  65. GRB 070224: WHT K-band imaging
  66. GRB 070224: MDM Observations
  67. GRB070224: Gemini Imaging Observations
  68. GRB 070224: SARA upper limit
  69. GRB070224: Swift-XRT Refined Analysis
  70. GRB 070224: optical afterglow candidate
  71. GRB 070224, Swift-BAT refined analysis
  72. GRB 070224: MASTER-Net refind analysis
  73. GRB 070224: MASTER-VWF-Kislovodsk observations
  74. GRB 070224: MASTER observations
  75. GRB 070224: Swift detection of a burst
  76. GRB 070223: Optical observations
  77. RHESSI Spectrum of GRB070220
  78. GRB070223: Swift/UVOT refined analysis
  79. GRB 070223: Optical-IR observation with KANATA
  80. GRB 070223, Swift-BAT refined analysis
  81. GRB070223: MASTER-VWF-Kislovodsk observations
  82. GRB 070223: Swift-XRT Refined Analysis
  83. GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
  84. GRB070223 - SDSS Pre-Burst Observations
  85. GRB 070223: Liverpool Telescope Possible Afterglow Candidate
  86. GRB 070223: MDM Observations
  87. GRB070223: Swift burst
  88. Konus-Wind and Konus-A observations of GRB 070220
  89. GRB 070220: MITSuME Okayama Optical Observation
  90. GRB 070220: ART-3 Optical and NIR limits
  91. GRB 070220 Swift-BAT Refined Analysis
  92. Swift/UVOT refined analysis of GRB070220
  93. GRB 070209: Swift XRT refined analysis
  94. GRB 070220: Swift-XRT Refined Analysis
  95. GRB 070220: Observation with the KANATA 1.5m telescope
  96. GRB 070219: Gemini Observations
  97. GRB 070220 : Faulkes Telescope North optical limit
  98. GRB 070220: Swift detection of a burst
  99. GRB070219: MASTER-VWF-Kislovodsk observations
  100. GRB 070219: XRT Refined Analysis

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