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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 090530: Early RAPTOR Optical Observations
  2. GRB090529B: ROVOR Upper Limits
  3. GRB 090531A: SARA upper limit
  4. GRB 090531B: Swift/BAT spectral lag results
  5. GRB 090529C: Fermi GBM detection
  6. GRB 090529B: Fermi GBM detection
  7. GRB 090530B: Fermi GBM detection
  8. Corrections to GRB 090531B Swift/UVOT Upper Limits
  9. GRB 090531B, RIMOTS optical upper limits
  10. GRB 090531B: Swift/UVOT Upper Limits
  11. GRB 090528B: MASTER-II Kourovka optical limit
  12. GRB 090529: MITSuME optical observation
  13. GRB 090530: GRT Optical Observation
  14. GRB 090531B: Swift-BAT refined analysis
  15. Initial Swift/UVOT observations of GRB 090531B
  16. GRB 090531B: Swift-XRT candidate afterglow position
  17. GRB 090531B: ROTSE-III Optical Limits
  18. GRB 090531B: Swift detection of a burst
  19. GRB 090531: Swift-BAT refined analysis
  20. GRB090530: R-band Observation
  21. GRB 090530: break in light curve
  22. GRB 090529: VLT spectroscopic redshift
  23. GRB 090531: GROND upper limits
  24. GRB 090531: P60 Observations
  25. GRB 090531: Swift detection of a burst
  26. GRB 090529: NOT optical observations
  27. GRB 090530: NOT optical observations
  28. GRB090530: Swift XRT refined analysis
  29. GRB090530: Swift/UVOT afterglow detection
  30. GRB 090529: Swift-XRT refined analysis
  31. GRB 090529: OSN optical observations
  32. GRB 090528B: Fermi GBM detection
  33. GRB 090528: Fermi GBM detection
  34. GRB 090530: Enhanced Swift-XRT position
  35. Strong radio emission from SN 2007bg one year after the explosion - detection of spreading, off-axis GRB jet?
  36. GRB 090530: Swift-BAT refined analysis
  37. GRB 090530: GRAS002 refined OA analysis
  38. GRB 090530: GRAS002 optical observations
  39. GRB 090530: PAIRITEL NIR Detections
  40. GRB 090530A: ROTSE-III Detection of Optical Counterpart
  41. GRB 090530: Swift detection of a burst with an optical counterpart
  42. GRB 090529: optical observations
  43. GRB 090529: TLS Afterglow Observations
  44. GRB090529: UVOT/Swift detection of a brightening optical afterglow
  45. GRB 090529: Swift-BAT refined analysis
  46. GRB 090529: Enhanced Swift-XRT position
  47. GRB 090529: Preliminary Swift/UVOT Upper Limit
  48. GRB 090529: Xinglong TNT optical observation
  49. GRB 090529: Swift detection of a burst
  50. GRB 090520D: Fermi GBM detection
  51. GRB 090520C: Fermi GBM detection
  52. GRB 090520B: Fermi GBM detection
  53. GRB090518B optical limit by "Pi of the Sky"
  54. GRB 090522 : Fermi GBM detection
  55. GRB 090524: Fermi GBM detection
  56. GRB 090518 - NOT upper limit
  57. GRB 090516A: Konus-Wind and Swift/BAT joint spectral analysis
  58. GRB 090513B: Fermi GBM detection
  59. GRB 090520: GROND upper limits
  60. GRB 090518: Fermi GBM detection
  61. GRB 090516C: Fermi GBM detection
  62. GRB 090520 Swift-BAT detection of a burst in ground analysis
  63. GRB 090423: Fermi GBM T90 follow-up analysis results
  64. GRB 090516: Fermi GBM observation
  65. GRB 090516B: Fermi GBM detection
  66. GRB 090519B: Fermi GBM detection
  67. GRB 090519: Swift-XRT refined analysis
  68. GRB 090519: NOT refined analysis
  69. GRB 090519: VLT spectroscopic redshift
  70. GRB 090519: GROND observation
  71. GRB 090519: Swift/UVOT Upper Limits
  72. GRB 090519, Swift-BAT refined analysis
  73. GRB 090519: Enhanced Swift-XRT position
  74. GRB 090519: Limits from BOOTES-1B
  75. GRB 090519: NOT afterglow candidate
  76. GRB 090519: FARO Chante Perdrix Observatory optical observations
  77. GRB 090519: TAROT Calern observatory optical observations
  78. GRB 090519: Swift detection of a burst
  79. GRB 090511: Fermi GBM Detection
  80. GRB 090514: Fermi GBM detection
  81. GRB 090518: Swift/UVOT Upper Limits
  82. GRB 090516: Observations from Stardome Observatory
  83. GRB090518: GROND upper limits
  84. GRB 090518: P60 Observations
  85. GRB 090518, Swift-BAT refined analysis
  86. GRB 090518B: Fermi GBM detection
  87. GRB 090516, RIMOTS optical upper limits
  88. GRB090513: Fermi GBM detection
  89. GRB090518 : Optical upper limit by MOA-II telescope
  90. GRB 090518: Swift-XRT refined analysis
  91. GRB 090518: Enhanced Swift-XRT position
  92. GRB 090518: Swift detection of a burst
  93. GRB 090515: Swift/BAT spectral lag results
  94. GRB 090516: Swift-BAT refined analysis
  95. GRB 090516: VLT spectrum (correction & update)
  96. GRB 090516: GROND OBSERVATIONS
  97. GRB 090516: VLT redshift
  98. GRB 090516 - Zadko Telescope observations
  99. GRB 090516: NOT optical observations
  100. GRB 090516: Swift XRT refined analysis

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