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

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