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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 090306B: Confirmation of the X-ray afterglow
  2. GRB 090313: Swift-BAT refined analysis
  3. GRB 090313: Sustained optical brightness
  4. GRB 090313: SDSS object underlying the optical afterglow position
  5. GRB 090313, GROND observations
  6. GRB 090309, Swift-BAT lag analysis
  7. GRB 090313: Swift detection of a burst
  8. GRB 090313: Swift detection of a burst
  9. GRB 090313 OA candidate
  10. Swift trigger 346250 is probably not a burst
  11. GRB090310: Fermi GBM detection
  12. GRB 090205: Zadko Telescope late-time observations
  13. GRB 090309A: GROND upper limits
  14. GRB 090307A: TAROT Calern observatory optical observations
  15. GRB 090309: Swift/UVOT Upper Limits
  16. GRB090305B: Fermi GBM detection
  17. GRB 090309B: Fermi GBM detection
  18. GRB 090309: Swift-XRT refined analysis
  19. GRB 090309: Enhanced Swift-XRT position
  20. GRB 090306B: INTEGRAL SPI-ACS light curve
  21. GRB 090309, Swift-BAT refined analysis
  22. GRB 090308: GROND observations
  23. GRB 090308: Gemini GMOS Observations
  24. GRB 090309: Swift detection of a burst
  25. GRB 090308B: Fermi GBM detection
  26. GRB 090308: Swift/UVOT Upper Limits
  27. GRB 090307B: Fermi GBM detection
  28. GRB 090306C: Fermi GBM detection
  29. GRB 090307: GROND Upper Limits
  30. GRB 090306B: GROND Upper Limits
  31. GRB 090305C: Suzaku WAM observation of the prompt emission
  32. GRB 090308: Swift-XRT refined analysis
  33. Radio observation of GRB 090201 with ATCA
  34. Radio observation of GRB 090117 with ATCA
  35. Radio observation of GRB 081226b with ATCA
  36. Radio observation of GRB 081226a with ATCA
  37. Radio observation of GRB 081007 with ATCA
  38. ATCA observation of SGR J1550-5418
  39. GRB 090308: Swift-BAT refined analysis
  40. GRB 090308: Swift detection of a burst
  41. GRB 090306B: Possible XRT afterglow
  42. GRB 090307: Swift-XRT afterglow confirmation and analysis
  43. GRB 090307: Swift-BAT refined analysis of trigger 345551
  44. GRB 090306B: Burst detection from Swift-BAT slew data
  45. Swift Trigger 345551 is probably not a GRB
  46. Swift-BAT trigger 345396 is not a GRB
  47. IPN localization of short GRB 090305C
  48. Fermi GBM trigger 090305784 is not a GRB
  49. GRB 090306: Swift detection of a possible burst
  50. GRB 090305: Swift/UVOT Upper Limits
  51. GRB 090305: Swift-XRT refined analysis
  52. GRB 090305, Swift-BAT refined analysis
  53. GRB 090227A: Suzaku WAM observation of the prompt emission
  54. GRB 090305: Magellan confirmation of the optical afterglow
  55. GRB090305: GMOS-S Candidate Optical Afterglow
  56. GRB 090305: Swift detection of a short burst
  57. GRB 090303: Fermi GBM detection
  58. GRB 090304: Fermi GBM detection
  59. GRB 090301A: Suzaku WAM observation of the prompt emission
  60. Konus-RF catches first GRB and SGR bursts
  61. GRB 090228B: Fermi GBM detection
  62. Konus-Wind observation of bright short GRB 090227B
  63. IPN localization of short bright GRB 090227B
  64. Konus-Wind observation of GRB 090301A
  65. GRB 090301A: Swift-BAT refined analysis
  66. GRB 090301B: Fermi GBM detection
  67. GRB 090227B: Fermi GBM detection
  68. GRB 090301: Swift detection of a burst
  69. Swift_BAT_Lightcurve Notice for Trigger Number 344565 is not valid
  70. GRB 090228: Fermi GBM detection
  71. GRB 090227: Fermi GBM detection
  72. GRB 090206: Fermi GBM detection
  73. SGR J1550-5418
  74. GRB 081211B: Nearby cluster
  75. Ongoing activity of AXP/SGR 1E1547.0-5408
  76. GRB 090222: Fermi GBM detection
  77. GRB 090219: Fermi GBM detection
  78. Swift Restored
  79. Swift Trigger 343319 is not a GRB
  80. GRB 090217: Suzaku WAM observation of the prompt emission
  81. GRB090217: XRT analysis
  82. Konus-Wind observation of GRB 090217
  83. IPN localization of GRB 090217
  84. GRB 090213: Fermi GBM detection
  85. GRB090217: Fermi-LAT Detection
  86. GRB 090217: Fermi GBM detection
  87. SGR activity seen by BAT during ICSP Ionospheric Events
  88. Detailed lightcurves of ICSP VLF Observation of SGR/AXP 1E1547.0-5408
  89. GRB 090207 - Fermi GBM Observations
  90. Fermi Gamma-ray Burst Monitor trigger 255729682 is not a GRB
  91. GRB 090129: Fermi GBM detection
  92. VLA radio upper limit on GRB 090205
  93. GRB 090205: VLT optical decay
  94. Fermi Gamma-ray Burst Monitor trigger 255541748 cannot be classified
  95. GRB 090205: Swift/UVOT Upper Limits
  96. GRB 090205: VLT refined redshift
  97. GRB 090205: Swift-XRT refined analysis
  98. GRB 090205: Swift burst of interest
  99. GRB 090205: VLT spectroscopic redshift
  100. GRB 090205: GROND observations and photometric redshift estimate

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