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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. Further radio observation of GRB 090313
  2. Further Swift/UVOT observations of GRB 090313
  3. GRB 090313: detection with CARMA in 3mm band
  4. GRB090305B: MASTER-net prompt optical short burst observations
  5. Radio detection of GRB090313
  6. GRB 090313: MITSuME Okayama observation
  7. GRB 090313: Additional Gemini-S photometry
  8. GRB 090313: WSRT Radio Observations
  9. GRB 090313: Light curve steepening
  10. GRB 090313: TAROT La Silla observatory optical detection
  11. GRB 090313: Gemini-S photometry
  12. GRB 090313: Zadko Telescope observations
  13. GRB 090313 - PAIRITEL NIR detections
  14. GRB 090313: Gemini-S redshift
  15. GRB 090313 optical observations
  16. GRB 090313: Ongoing plateau phase
  17. GRB 090313: Swift-XRT refined analysis
  18. GRB 090313: Swift/UVOT upper limits
  19. GRB 090313: Faulkes Telescope North observations
  20. GRB 090313: Sustained optical brightness (correction)
  21. GRB 090306B: Confirmation of the X-ray afterglow
  22. GRB 090313: Swift-BAT refined analysis
  23. GRB 090313: Sustained optical brightness
  24. GRB 090313: SDSS object underlying the optical afterglow position
  25. GRB 090313, GROND observations
  26. GRB 090309, Swift-BAT lag analysis
  27. GRB 090313: Swift detection of a burst
  28. GRB 090313: Swift detection of a burst
  29. GRB 090313 OA candidate
  30. Swift trigger 346250 is probably not a burst
  31. GRB090310: Fermi GBM detection
  32. GRB 090205: Zadko Telescope late-time observations
  33. GRB 090309A: GROND upper limits
  34. GRB 090307A: TAROT Calern observatory optical observations
  35. GRB 090309: Swift/UVOT Upper Limits
  36. GRB090305B: Fermi GBM detection
  37. GRB 090309B: Fermi GBM detection
  38. GRB 090309: Swift-XRT refined analysis
  39. GRB 090309: Enhanced Swift-XRT position
  40. GRB 090306B: INTEGRAL SPI-ACS light curve
  41. GRB 090309, Swift-BAT refined analysis
  42. GRB 090308: GROND observations
  43. GRB 090308: Gemini GMOS Observations
  44. GRB 090309: Swift detection of a burst
  45. GRB 090308B: Fermi GBM detection
  46. GRB 090308: Swift/UVOT Upper Limits
  47. GRB 090307B: Fermi GBM detection
  48. GRB 090306C: Fermi GBM detection
  49. GRB 090307: GROND Upper Limits
  50. GRB 090306B: GROND Upper Limits
  51. GRB 090305C: Suzaku WAM observation of the prompt emission
  52. GRB 090308: Swift-XRT refined analysis
  53. Radio observation of GRB 090201 with ATCA
  54. Radio observation of GRB 090117 with ATCA
  55. Radio observation of GRB 081226b with ATCA
  56. Radio observation of GRB 081226a with ATCA
  57. Radio observation of GRB 081007 with ATCA
  58. ATCA observation of SGR J1550-5418
  59. GRB 090308: Swift-BAT refined analysis
  60. GRB 090308: Swift detection of a burst
  61. GRB 090306B: Possible XRT afterglow
  62. GRB 090307: Swift-XRT afterglow confirmation and analysis
  63. GRB 090307: Swift-BAT refined analysis of trigger 345551
  64. GRB 090306B: Burst detection from Swift-BAT slew data
  65. Swift Trigger 345551 is probably not a GRB
  66. Swift-BAT trigger 345396 is not a GRB
  67. IPN localization of short GRB 090305C
  68. Fermi GBM trigger 090305784 is not a GRB
  69. GRB 090306: Swift detection of a possible burst
  70. GRB 090305: Swift/UVOT Upper Limits
  71. GRB 090305: Swift-XRT refined analysis
  72. GRB 090305, Swift-BAT refined analysis
  73. GRB 090227A: Suzaku WAM observation of the prompt emission
  74. GRB 090305: Magellan confirmation of the optical afterglow
  75. GRB090305: GMOS-S Candidate Optical Afterglow
  76. GRB 090305: Swift detection of a short burst
  77. GRB 090303: Fermi GBM detection
  78. GRB 090304: Fermi GBM detection
  79. GRB 090301A: Suzaku WAM observation of the prompt emission
  80. Konus-RF catches first GRB and SGR bursts
  81. GRB 090228B: Fermi GBM detection
  82. Konus-Wind observation of bright short GRB 090227B
  83. IPN localization of short bright GRB 090227B
  84. Konus-Wind observation of GRB 090301A
  85. GRB 090301A: Swift-BAT refined analysis
  86. GRB 090301B: Fermi GBM detection
  87. GRB 090227B: Fermi GBM detection
  88. GRB 090301: Swift detection of a burst
  89. Swift_BAT_Lightcurve Notice for Trigger Number 344565 is not valid
  90. GRB 090228: Fermi GBM detection
  91. GRB 090227: Fermi GBM detection
  92. GRB 090206: Fermi GBM detection
  93. SGR J1550-5418
  94. GRB 081211B: Nearby cluster
  95. Ongoing activity of AXP/SGR 1E1547.0-5408
  96. GRB 090222: Fermi GBM detection
  97. GRB 090219: Fermi GBM detection
  98. Swift Restored
  99. Swift Trigger 343319 is not a GRB
  100. GRB 090217: Suzaku WAM observation of the prompt emission

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