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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"

28095 results found.

  1. GRB 090404: NOT observations
  2. GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
  3. GRB 090404: Swift-XRT Team refined analysis
  4. GRB 090404: Enhanced Swift-XRT position
  5. GRB 090404: Swift detection of a burst
  6. GRB 090401B: VLA radio upper limit
  7. GRB 090401B: Upper limits of MITSuME optical observation
  8. GRB 090401B: NOT optical observations
  9. Swift/UVOT observations of GRB090401B
  10. GRB 090401B: AGILE refined analysis
  11. Swift/UVOT observations of GRB090401B
  12. GRB 090401B: Swift XRT Refined Analysis
  13. GRB 090331: Fermi GBM detection
  14. GRB 090401B: Enhanced Swift-XRT position
  15. AGILE Gamma-ray detection of GRB 090401B
  16. Swift/UVOT detection of GRB090401B
  17. GRB 090401B: Swift detection of a burst
  18. GRB 090323: Further TLS detections - a break?
  19. GRB 090401: Swift detection of a burst
  20. GRB 090328: Radio afterglow detection
  21. GRB 090326: Fermi GBM detection
  22. GRB 090328: BOOTES-3 optical observations
  23. GRB 090328B: Fermi GBM Detection
  24. GRB 090330: Fermi GBM detection
  25. GRB 090328: GROND Detection of the Optical/NIR Afterglow
  26. GRB 090328: Gemini South Redshift
  27. GRB 090328: Swift XRT refined analysis
  28. GRB090323: Optical observations from NOT
  29. GRB 090328: Swift UVOT observations
  30. GRB 090323: WSRT Radio Detection
  31. GRB 090328: Updated position/optical afterglow candidate
  32. GRB 090328: Possible Swift/XRT detection
  33. Fermi LAT and GBM detections of GRB090328
  34. GRB 090323: Radio afterglow detection
  35. GRB 090323: Additional Lick observations
  36. GRB 090323: TLS detection at 5 days, no break
  37. GRB 090327: Fermi GBM detection
  38. GRB 090323: Faulkes Telescope South Observations
  39. GRB 090323: RTT150 optical observations
  40. GRB 090323: Lick observations
  41. GRB 090323: Optical observation of xinglong TNT
  42. GRB 090323 TLS detection - still bright
  43. GRB 090323: UVOT Detection of Afterglow
  44. GRB 090323: Swift-XRT refined analysis
  45. GRB 090323 Gemini-South Redshift
  46. GRB 090323: P60 Afterglow Confirmation
  47. GRB 090323: GROND Detection of the Afterglow and Photo-z
  48. GRB 090323: Possible XRT Counterpart
  49. GRB 090320C: Fermi GBM Detection
  50. GRB 090320B: Fermi GBM detection.
  51. GRB 090319: Fermi GBM detection
  52. GRB 090320A: Fermi GBM detection
  53. GRB 090313: WSRT Radio Detection
  54. X-shooter observations of GRB 090313
  55. GRB 090313: VLT spectroscopy
  56. GRB090313: radio detection with the VLA
  57. IPN Triangulation of GRB090315 and Tupi Detection of Muon Increase
  58. GRB 090313, SMARTS optical/IR observations
  59. Further Swift/UVOT observations of GRB 090313
  60. GRB 090313: detection with CARMA in 3mm band
  61. Radio detection of GRB090313
  62. GRB 090313: MITSuME Okayama observation
  63. GRB 090313: Additional Gemini-S photometry
  64. GRB 090313: WSRT Radio Observations
  65. GRB 090313: Light curve steepening
  66. GRB 090313: TAROT La Silla observatory optical detection
  67. GRB 090313: Gemini-S photometry
  68. GRB 090313: Zadko Telescope observations
  69. GRB 090313 - PAIRITEL NIR detections
  70. GRB 090313: Gemini-S redshift
  71. GRB 090313 optical observations
  72. GRB 090313: Ongoing plateau phase
  73. GRB 090313: Swift-XRT refined analysis
  74. GRB 090313: Swift/UVOT upper limits
  75. GRB 090313: Faulkes Telescope North observations
  76. GRB 090306B: Confirmation of the X-ray afterglow
  77. GRB 090313: Sustained optical brightness
  78. GRB 090313: SDSS object underlying the optical afterglow position
  79. GRB 090313, GROND observations
  80. GRB 090313: Swift detection of a burst
  81. GRB 090313: Swift detection of a burst
  82. GRB090310: Fermi GBM detection
  83. GRB 090205: Zadko Telescope late-time observations
  84. GRB 090309A: GROND upper limits
  85. GRB 090307A: TAROT Calern observatory optical observations
  86. GRB 090309: Swift/UVOT Upper Limits
  87. GRB090305B: Fermi GBM detection
  88. GRB 090309B: Fermi GBM detection
  89. GRB 090309: Swift-XRT refined analysis
  90. GRB 090309: Enhanced Swift-XRT position
  91. GRB 090308: GROND observations
  92. GRB 090308: Gemini GMOS Observations
  93. GRB 090309: Swift detection of a burst
  94. GRB 090308B: Fermi GBM detection
  95. GRB 090308: Swift/UVOT Upper Limits
  96. GRB 090307B: Fermi GBM detection
  97. GRB 090306C: Fermi GBM detection
  98. GRB 090307: GROND Upper Limits
  99. GRB 090306B: GROND Upper Limits
  100. GRB 090308: Swift-XRT refined analysis

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