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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 090313 OA candidate
  2. Swift trigger 346250 is probably not a burst
  3. GRB090310: Fermi GBM detection
  4. GRB 090205: Zadko Telescope late-time observations
  5. GRB 090309A: GROND upper limits
  6. GRB 090307A: TAROT Calern observatory optical observations
  7. GRB 090309: Swift/UVOT Upper Limits
  8. GRB090305B: Fermi GBM detection
  9. GRB 090309B: Fermi GBM detection
  10. GRB 090309: Swift-XRT refined analysis
  11. GRB 090309: Enhanced Swift-XRT position
  12. GRB 090306B: INTEGRAL SPI-ACS light curve
  13. GRB 090309, Swift-BAT refined analysis
  14. GRB 090308: GROND observations
  15. GRB 090308: Gemini GMOS Observations
  16. GRB 090309: Swift detection of a burst
  17. GRB 090308B: Fermi GBM detection
  18. GRB 090308: Swift/UVOT Upper Limits
  19. GRB 090307B: Fermi GBM detection
  20. GRB 090306C: Fermi GBM detection
  21. GRB 090307: GROND Upper Limits
  22. GRB 090306B: GROND Upper Limits
  23. GRB 090305C: Suzaku WAM observation of the prompt emission
  24. GRB 090308: Swift-XRT refined analysis
  25. Radio observation of GRB 090201 with ATCA
  26. Radio observation of GRB 090117 with ATCA
  27. Radio observation of GRB 081226b with ATCA
  28. Radio observation of GRB 081226a with ATCA
  29. Radio observation of GRB 081007 with ATCA
  30. ATCA observation of SGR J1550-5418
  31. GRB 090308: Swift-BAT refined analysis
  32. GRB 090308: Swift detection of a burst
  33. GRB 090306B: Possible XRT afterglow
  34. GRB 090307: Swift-XRT afterglow confirmation and analysis
  35. GRB 090307: Swift-BAT refined analysis of trigger 345551
  36. GRB 090306B: Burst detection from Swift-BAT slew data
  37. Swift Trigger 345551 is probably not a GRB
  38. Swift-BAT trigger 345396 is not a GRB
  39. IPN localization of short GRB 090305C
  40. Fermi GBM trigger 090305784 is not a GRB
  41. GRB 090306: Swift detection of a possible burst
  42. GRB 090305: Swift/UVOT Upper Limits
  43. GRB 090305: Swift-XRT refined analysis
  44. GRB 090305, Swift-BAT refined analysis
  45. GRB 090227A: Suzaku WAM observation of the prompt emission
  46. GRB 090305: Magellan confirmation of the optical afterglow
  47. GRB090305: GMOS-S Candidate Optical Afterglow
  48. GRB 090305: Swift detection of a short burst
  49. GRB 090303: Fermi GBM detection
  50. GRB 090304: Fermi GBM detection
  51. GRB 090301A: Suzaku WAM observation of the prompt emission
  52. Konus-RF catches first GRB and SGR bursts
  53. GRB 090228B: Fermi GBM detection
  54. Konus-Wind observation of bright short GRB 090227B
  55. IPN localization of short bright GRB 090227B
  56. Konus-Wind observation of GRB 090301A
  57. GRB 090301A: Swift-BAT refined analysis
  58. GRB 090301B: Fermi GBM detection
  59. GRB 090227B: Fermi GBM detection
  60. GRB 090301: Swift detection of a burst
  61. Swift_BAT_Lightcurve Notice for Trigger Number 344565 is not valid
  62. GRB 090228: Fermi GBM detection
  63. GRB 090227: Fermi GBM detection
  64. GRB 090206: Fermi GBM detection
  65. SGR J1550-5418
  66. GRB 081211B: Nearby cluster
  67. Ongoing activity of AXP/SGR 1E1547.0-5408
  68. GRB 090222: Fermi GBM detection
  69. GRB 090219: Fermi GBM detection
  70. Swift Restored
  71. Swift Trigger 343319 is not a GRB
  72. GRB 090217: Suzaku WAM observation of the prompt emission
  73. GRB090217: XRT analysis
  74. Konus-Wind observation of GRB 090217
  75. IPN localization of GRB 090217
  76. GRB 090213: Fermi GBM detection
  77. GRB090217: Fermi-LAT Detection
  78. GRB 090217: Fermi GBM detection
  79. SGR activity seen by BAT during ICSP Ionospheric Events
  80. Detailed lightcurves of ICSP VLF Observation of SGR/AXP 1E1547.0-5408
  81. GRB 090207 - Fermi GBM Observations
  82. Fermi Gamma-ray Burst Monitor trigger 255729682 is not a GRB
  83. GRB 090129: Fermi GBM detection
  84. VLA radio upper limit on GRB 090205
  85. GRB 090205: VLT optical decay
  86. Fermi Gamma-ray Burst Monitor trigger 255541748 cannot be classified
  87. GRB 090205: Swift/UVOT Upper Limits
  88. GRB 090205: VLT refined redshift
  89. GRB 090205: Swift-XRT refined analysis
  90. GRB 090205: Swift burst of interest
  91. GRB 090205: VLT spectroscopic redshift
  92. GRB 090205: GROND observations and photometric redshift estimate
  93. GRB 090205: VLT candidate afterglow
  94. GRB 090205: Swift-BAT refined analysis
  95. GRB 090205: Enhanced Swift-XRT position
  96. GRB 090205: Swift detection of a burst
  97. GRB 080319B: IceCube upper limit on high-energy neutrino flux
  98. GRB 090131: Suzaku WAM observation of the prompt emission
  99. ICSP VLF observation of the signatures of SGR/AXP 1E1547.0-5408 bursts
  100. GRB 090126A: Swift-XRT afterglow confirmation

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