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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. GRB070318: Swift UVOT continuing observations
  2. GRB070318: Swift-XRT refined analysis
  3. GRB 070318: Swift/UVOT Continued Observations
  4. GRB 070318, Swift-BAT refined analysis
  5. IBAS Alert n. 4176: not a GRB
  6. GRB 070318: Swift detection of a burst with an optical afterglow
  7. GRB 070311: Late Central Engine Activity Optical Flare??
  8. GRB 070311: MDM Optical Monitoring
  9. VLA observation of GRB 070311
  10. GRB 070311: Tautenburg sees afterglow fading
  11. IBAS Alert n. 4169: not a GRB
  12. GRB 070311: Optical observation.
  13. GRB 070311: Optical Brightening
  14. GRB 070306: possible emission-line redshift
  15. GRB 070311: SARA upper limit
  16. GRB 070309: variability of the XRT afterglow candidate
  17. GRB 070311: MDM Optical Follow-up
  18. GRB 070311: RAPTOR Detection of Optical Emission
  19. GRB070311: FRAM early follow-up limit
  20. GRB 070311: P60 Observations
  21. GRB 070311: MDM Optical Detection
  22. GRB 070311: Swift/UVOT Upper Limits
  23. GRB 070311: MITSuME Okayama Optical Observation
  24. GRB 070311: Swift-XRT refined analysis
  25. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  26. GRB 070311: REM candidate afterglow
  27. GRB 070311: a long GRB detected by INTEGRAL
  28. GRB060901: Candidate optical afterglow
  29. GRB070309: Swift/XRT possible afterglow detection
  30. GRB 070125: Chandra X-ray Confirmation of Jet Break
  31. GRB 070309: Swift/UVOT Upper Limits
  32. GRB 070306, optical observation
  33. Swift UVOT Finding Charts for GRB 070309
  34. GRB 070309: A long GRB detected by INTEGRAL
  35. GRB 070125: X-ray light curve analysis
  36. VLA observation of GRB 070306
  37. IBAS Alert 4162: Not a GRB
  38. GRB 070306: NOT observations
  39. GRB 070306 Swift/UVOT refined analysis
  40. GRB070306: confirmation of near infrared afterglow
  41. GRB 070306: ART-3 early optical and near infrared constraints
  42. GRB 070306: IR observations and candidate afterglow
  43. GRB 070306, Swift-BAT refined analysis
  44. GRB 070306: XRT Team Refined Analysis
  45. GRB 070306: Optical and IR observations with KANATA
  46. GRB070306 - SDSS Pre-burst Observations
  47. GRB 070306: Swift detection of a burst
  48. GRB 070223: NIR observations at WHT
  49. GRB070227: Swift-XRT refined analysis
  50. GRB 060605 new redshift
  51. GRB 070125, deep late-time optical observation
  52. VLA observation of GRB 070224
  53. GRB 070227: optical observations
  54. GRB 070223: Optical Observations
  55. GRB 070227: optical observations
  56. GRB 070227: Swift/UVOT Upper Limits
  57. GRB 070227: TAROT La Silla observatory optical observations
  58. GRB 070227, Swift-BAT refined analysis
  59. GRB070227: possible X-ray afterglow detection
  60. GRB 070227: Swift detection of a burst in ground analysis
  61. GRB 920925C: optical afterglow candidate
  62. GRB 070224: Optical afterglow confirmation
  63. IBAS Alert n. 4144: not a GRB
  64. GRB 070224: Swift/UVOT Upper Limits
  65. GRB070224: Swift-XRT Astrometrically Corrected Position
  66. VLA observation of GRB 070223
  67. VLA observation of GRB 070220
  68. GRB070224: Magellan Imaging Observations
  69. GRB 070224: WHT K-band imaging
  70. GRB 070224: MDM Observations
  71. GRB070224: Gemini Imaging Observations
  72. GRB 070224: SARA upper limit
  73. GRB070224: Swift-XRT Refined Analysis
  74. GRB 070224: optical afterglow candidate
  75. GRB 070224, Swift-BAT refined analysis
  76. GRB 070224: MASTER-Net refind analysis
  77. GRB 070224: MASTER-VWF-Kislovodsk observations
  78. GRB 070224: MASTER observations
  79. GRB 070224: Swift detection of a burst
  80. GRB 070223: Optical observations
  81. RHESSI Spectrum of GRB070220
  82. GRB070223: Swift/UVOT refined analysis
  83. GRB 070223: Optical-IR observation with KANATA
  84. GRB 070223, Swift-BAT refined analysis
  85. GRB070223: MASTER-VWF-Kislovodsk observations
  86. GRB 070223: Swift-XRT Refined Analysis
  87. GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
  88. GRB070223 - SDSS Pre-Burst Observations
  89. GRB 070223: Liverpool Telescope Possible Afterglow Candidate
  90. GRB 070223: MDM Observations
  91. GRB070223: Swift burst
  92. Konus-Wind and Konus-A observations of GRB 070220
  93. GRB 070220: MITSuME Okayama Optical Observation
  94. GRB 070220: ART-3 Optical and NIR limits
  95. GRB 070220 Swift-BAT Refined Analysis
  96. Swift/UVOT refined analysis of GRB070220
  97. GRB 070209: Swift XRT refined analysis
  98. GRB 070220: Swift-XRT Refined Analysis
  99. GRB 070220: Observation with the KANATA 1.5m telescope
  100. GRB 070219: Gemini Observations

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