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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. Initial Swift/UVOT observations of GRB 090531B
  2. GRB 090531B: Swift-XRT candidate afterglow position
  3. GRB 090531B: ROTSE-III Optical Limits
  4. GRB 090531B: Swift detection of a burst
  5. GRB 090531: Swift-BAT refined analysis
  6. GRB090530: R-band Observation
  7. GRB 090530: break in light curve
  8. GRB 090529: VLT spectroscopic redshift
  9. GRB 090531: GROND upper limits
  10. GRB 090531: P60 Observations
  11. GRB 090531: Swift detection of a burst
  12. GRB 090529: NOT optical observations
  13. GRB 090530: NOT optical observations
  14. GRB090530: Swift XRT refined analysis
  15. GRB090530: Swift/UVOT afterglow detection
  16. GRB 090529: Swift-XRT refined analysis
  17. GRB 090529: OSN optical observations
  18. GRB 090528B: Fermi GBM detection
  19. GRB 090528: Fermi GBM detection
  20. GRB 090530: Enhanced Swift-XRT position
  21. Strong radio emission from SN 2007bg one year after the explosion - detection of spreading, off-axis GRB jet?
  22. GRB 090530: Swift-BAT refined analysis
  23. GRB 090530: GRAS002 refined OA analysis
  24. GRB 090530: GRAS002 optical observations
  25. GRB 090530: PAIRITEL NIR Detections
  26. GRB 090530A: ROTSE-III Detection of Optical Counterpart
  27. GRB 090530: Swift detection of a burst with an optical counterpart
  28. GRB 090529: optical observations
  29. GRB 090529: TLS Afterglow Observations
  30. GRB090529: UVOT/Swift detection of a brightening optical afterglow
  31. GRB 090529: Swift-BAT refined analysis
  32. GRB 090529: Enhanced Swift-XRT position
  33. GRB 090529: Preliminary Swift/UVOT Upper Limit
  34. GRB 090529: Xinglong TNT optical observation
  35. GRB 090529: Swift detection of a burst
  36. GRB 090520D: Fermi GBM detection
  37. GRB 090520C: Fermi GBM detection
  38. GRB 090520B: Fermi GBM detection
  39. GRB090518B optical limit by "Pi of the Sky"
  40. GRB 090522 : Fermi GBM detection
  41. GRB 090524: Fermi GBM detection
  42. GRB 090518 - NOT upper limit
  43. GRB 090516A: Konus-Wind and Swift/BAT joint spectral analysis
  44. GRB 090513B: Fermi GBM detection
  45. GRB 090520: GROND upper limits
  46. GRB 090518: Fermi GBM detection
  47. GRB 090516C: Fermi GBM detection
  48. GRB 090520 Swift-BAT detection of a burst in ground analysis
  49. GRB 090423: Fermi GBM T90 follow-up analysis results
  50. GRB 090516: Fermi GBM observation
  51. GRB 090516B: Fermi GBM detection
  52. GRB 090519B: Fermi GBM detection
  53. GRB 090519: Swift-XRT refined analysis
  54. GRB 090519: NOT refined analysis
  55. GRB 090519: VLT spectroscopic redshift
  56. GRB 090519: GROND observation
  57. GRB 090519: Swift/UVOT Upper Limits
  58. GRB 090519, Swift-BAT refined analysis
  59. GRB 090519: Enhanced Swift-XRT position
  60. GRB 090519: Limits from BOOTES-1B
  61. GRB 090519: NOT afterglow candidate
  62. GRB 090519: FARO Chante Perdrix Observatory optical observations
  63. GRB 090519: TAROT Calern observatory optical observations
  64. GRB 090519: Swift detection of a burst
  65. GRB 090511: Fermi GBM Detection
  66. GRB 090514: Fermi GBM detection
  67. GRB 090518: Swift/UVOT Upper Limits
  68. GRB 090516: Observations from Stardome Observatory
  69. GRB090518: GROND upper limits
  70. GRB 090518: P60 Observations
  71. GRB 090518, Swift-BAT refined analysis
  72. GRB 090518B: Fermi GBM detection
  73. GRB 090516, RIMOTS optical upper limits
  74. GRB090513: Fermi GBM detection
  75. GRB090518 : Optical upper limit by MOA-II telescope
  76. GRB 090518: Swift-XRT refined analysis
  77. GRB 090518: Enhanced Swift-XRT position
  78. GRB 090518: Swift detection of a burst
  79. GRB 090515: Swift/BAT spectral lag results
  80. GRB 090516: Swift-BAT refined analysis
  81. GRB 090516: VLT spectrum (correction & update)
  82. GRB 090516: GROND OBSERVATIONS
  83. GRB 090516: VLT redshift
  84. GRB 090516 - Zadko Telescope observations
  85. GRB 090516: NOT optical observations
  86. GRB 090516: Swift XRT refined analysis
  87. GRB 090516: Swift/UVOT Observations
  88. GRB 090516: Enhanced Swift-XRT position
  89. GRB 090516: Faulkes Telescope South optical afterglow
  90. GRB 090516: Swift detection of a burst
  91. GRB 090515: VLA observations
  92. GRB 090515: Lick Upper Limits
  93. GRB 090515: ROVOR Upper Limit
  94. GRB 090515: MMT/MMIRS NIR Upper Limit
  95. GRB 090515: Swift/UVOT Observations
  96. GRB 090515: Swift-XRT refined analysis
  97. GRB 090515: Enhanced Swift-XRT position
  98. GRB 090509: Fermi GBM observation
  99. GRB 090515: Swift-BAT refined spectral analysis
  100. GRB 090515: Swift-BAT refined analysis

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