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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 090328: GROND Detection of the Optical/NIR Afterglow
  2. GRB 090328: Gemini South Redshift
  3. GRB 090328: Swift XRT refined analysis
  4. GRB090323: Optical observations from NOT
  5. Konus-Wind observation of GRB 090328
  6. GRB 090328: IPN Triangulation
  7. GRB 090328: Swift UVOT observations
  8. GRB 090323: WSRT Radio Detection
  9. GRB 090328: Updated position/optical afterglow candidate
  10. GRB 090328: Possible Swift/XRT detection
  11. Fermi LAT and GBM detections of GRB090328
  12. GRB 090323: Radio afterglow detection
  13. GRB 090323: Additional Lick observations
  14. GRB 090323: TLS detection at 5 days, no break
  15. GRB 090327: Fermi GBM detection
  16. GRB 090323: Faulkes Telescope South Observations
  17. GRB 090320B: MASTER-Net prompt optical observations
  18. GRB 090323: RTT150 optical observations
  19. GRB 090323: Lick observations
  20. GRB 090323: Fermi GBM Spectral Analysis
  21. GRB 090323: Optical observation of xinglong TNT
  22. GRB 090323 TLS detection - still bright
  23. GRB 090323: UVOT Detection of Afterglow
  24. GRB 090323: Swift-XRT refined analysis
  25. Konus-Wind observation of GRB 090323
  26. GRB 090324: SuperAGILE Localization of a Long GRB
  27. GRB 090323 Gemini-South Redshift
  28. GRB 090323: P60 Afterglow Confirmation
  29. GRB 090323: GROND Detection of the Afterglow and Photo-z
  30. SGR J1550-5418: two Fermi GBM triggers on March 22
  31. GRB 090323: Possible XRT Counterpart
  32. IPN triangulation of GRB090323
  33. GRB 090320C: Fermi GBM Detection
  34. Fermi GBM and LAT detections of GRB 090323
  35. GRB 090320B: Fermi GBM detection.
  36. GRB 090319: Fermi GBM detection
  37. GRB 090320A: Fermi GBM detection
  38. Further 15GHz observations of GRB090313
  39. GRB 090313: WSRT Radio Detection
  40. X-shooter observations of GRB 090313
  41. A bright burst from AXP 1E 1547.0-5408/SGR J1550-5418
  42. GRB 090315: Suzaku WAM observation of the prompt emission
  43. GRB 090313: VLT spectroscopy
  44. GRB090313: radio detection with the VLA
  45. Konus-Wind observation of GRB 090315
  46. IPN Triangulation of GRB090315 and Tupi Detection of Muon Increase
  47. GRB 090313, SMARTS optical/IR observations
  48. Further radio observation of GRB 090313
  49. Further Swift/UVOT observations of GRB 090313
  50. GRB 090313: detection with CARMA in 3mm band
  51. GRB090305B: MASTER-net prompt optical short burst observations
  52. Radio detection of GRB090313
  53. GRB 090313: MITSuME Okayama observation
  54. GRB 090313: Additional Gemini-S photometry
  55. GRB 090313: WSRT Radio Observations
  56. GRB 090313: Light curve steepening
  57. GRB 090313: TAROT La Silla observatory optical detection
  58. GRB 090313: Gemini-S photometry
  59. GRB 090313: Zadko Telescope observations
  60. GRB 090313 - PAIRITEL NIR detections
  61. GRB 090313: Gemini-S redshift
  62. GRB 090313 optical observations
  63. GRB 090313: Ongoing plateau phase
  64. GRB 090313: Swift-XRT refined analysis
  65. GRB 090313: Swift/UVOT upper limits
  66. GRB 090313: Faulkes Telescope North observations
  67. GRB 090313: Sustained optical brightness (correction)
  68. GRB 090306B: Confirmation of the X-ray afterglow
  69. GRB 090313: Swift-BAT refined analysis
  70. GRB 090313: Sustained optical brightness
  71. GRB 090313: SDSS object underlying the optical afterglow position
  72. GRB 090313, GROND observations
  73. GRB 090309, Swift-BAT lag analysis
  74. GRB 090313: Swift detection of a burst
  75. GRB 090313: Swift detection of a burst
  76. GRB 090313 OA candidate
  77. Swift trigger 346250 is probably not a burst
  78. GRB090310: Fermi GBM detection
  79. GRB 090205: Zadko Telescope late-time observations
  80. GRB 090309A: GROND upper limits
  81. GRB 090307A: TAROT Calern observatory optical observations
  82. GRB 090309: Swift/UVOT Upper Limits
  83. GRB090305B: Fermi GBM detection
  84. GRB 090309B: Fermi GBM detection
  85. GRB 090309: Swift-XRT refined analysis
  86. GRB 090309: Enhanced Swift-XRT position
  87. GRB 090306B: INTEGRAL SPI-ACS light curve
  88. GRB 090309, Swift-BAT refined analysis
  89. GRB 090308: GROND observations
  90. GRB 090308: Gemini GMOS Observations
  91. GRB 090309: Swift detection of a burst
  92. GRB 090308B: Fermi GBM detection
  93. GRB 090308: Swift/UVOT Upper Limits
  94. GRB 090307B: Fermi GBM detection
  95. GRB 090306C: Fermi GBM detection
  96. GRB 090307: GROND Upper Limits
  97. GRB 090306B: GROND Upper Limits
  98. GRB 090305C: Suzaku WAM observation of the prompt emission
  99. GRB 090308: Swift-XRT refined analysis
  100. Radio observation of GRB 090201 with ATCA

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Download all Circulars as a .tar.gz archive (updated once a day):
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