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

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