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

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