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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 100526A: Swift XRT refined analysis
  2. GRB 100526B: Swift-BAT refined analysis
  3. GRB 100526B: Swift XRT/UVOT observations
  4. GRB 100526A: Swift-BAT refined analysis
  5. GRB 100526A: Enhanced Swift-XRT position
  6. GRB 100526B: Swift detection of a probable GRB
  7. GRB 100526A: MASTER-Net optical alert observations
  8. GRB 100526A: Swift detection of a burst
  9. Konus-Wind observation of GRB 100522A
  10. GRB100522A: Suzaku WAM observation of the prompt emission
  11. GRB 100418A: Subaru late-time optical imaging and spectroscopy
  12. GRB 100522A: GROND observations, upper limits
  13. Swift/UVOT observations of GRB100522A.
  14. GRB 100522A: Fermi GBM observation
  15. GRB 100522A: Swift XRT refined analysis
  16. GRB 100522A, Swift-BAT refined analysis
  17. GRB 100522A: Enhanced Swift-XRT position
  18. GRB 100522A: NIR observations from CAHA
  19. GRB 100522A: BOOTES-2 optical limit
  20. GRB 100522A: Swift detection of a burst
  21. GRB 100418A: CrAO optical observations
  22. GRB 100518A: GROND afterglow observation and photo-z
  23. GRB 100518A: Swift/UVOT Upper Limits
  24. GRB 100518A: Swift-XRT refined analysis
  25. GRB 100518A: optical afterglow decay
  26. GRB 100518A: BOOTES-3 optical observations
  27. Update to the configuration of the Fermi-LAT onboard GRB search
  28. GRB 100518A: Faulkes Telescope North Afterglow Candidate
  29. GRB 100518A: Swift target of opportunity observation of the INTEGRAL burst
  30. GRB 100513A: MITSuME Akeno Optical Observation
  31. Swift-BAT trigger 422437 is not anything astrophysical
  32. GRB 100518A: a long GRB detected with INTEGRAL
  33. Swift Trigger 422437 is probably not a GRB
  34. Fermi/GBM trigger 295791986 - unreliable location
  35. GRB 100517A: MASTER-Net wide field camera prompt optical observations
  36. GRB 100513A: EVLA radio observation
  37. GRB 100514A: optical afterglow confirmation
  38. GRB 100514A: Swift/UVOT Observations
  39. GRB 100514A: YNAO-GMG observations
  40. GRB 100514A: Swift XRT refined analysis
  41. GRB 100514A: MASTER-Net optical observations
  42. GRB 100514A: Enhanced Swift-XRT position
  43. GRB 100514A: Swift-BAT refined analysis
  44. GRB 100514A: Faulkes Telescope South observations
  45. GRB 100514A: Swift detection of a burst
  46. GRB 100513A: Faulkes Telescope South observations
  47. GRB 100513A: Swift/UVOT upper limits
  48. GRB 100513A, RIMOTS optical upper limits
  49. GRB 100513A: Swift XRT refined analysis
  50. GRB 100513A: Swift-BAT refined analysis
  51. GRB 100513A: Gemini/GMOS Spectroscopic Redshift
  52. GRB 100513A: Enhanced Swift-XRT position
  53. GRB 100513A: Lick observations and R-band dropout
  54. GRB 100513A: PAIRITEL continued observations and confirmation of fading
  55. GRB 100513A: SARA-N Upper Limit
  56. GRB 100513A: PAIRITEL NIR afterglow candidate
  57. GRB 100513A: Swift detection of a burst
  58. GRB 100510A: Fermi GBM detection/observation
  59. GRB 100511A: Fermi GBM detection/observation
  60. GRB 100511A: Super-LOTIS early observations
  61. Swift-BAT trigger 421695 is likely not astrophysical
  62. GRB100504A: Optical upper limits at IAO
  63. GRB 100510A: MAXI/GSC detection
  64. GRB 100511A, RIMOTS optical upper limits
  65. Trigger 421695: Swift detection of a possible burst
  66. GRB100508A: Further Swift/UVOT Observations
  67. GRB100503A: Suzaku WAM observation of the prompt emission
  68. GRB 100508A: GROND Detection of the optical afterglow
  69. GRB 100508A: Swift-XRT Refined analysis
  70. GRB 100508A: Swift-BAT refined analysis
  71. GRB 100508A: Enhanced Swift-XRT position
  72. GRB100508A: Swift/UVOT Detection of the Afterglow
  73. GRB 100508A: ROTSE-III Optical Limits
  74. GRB 100508A: Swift detection of a burst
  75. GRB 100418A: Keck imaging
  76. GRB 100418A: RTT150 optical observations
  77. Fermi Gamma-ray Burst Monitor trigger 294712621 is not a GRB
  78. Swift-BAT refined analysis of trigger 421262
  79. GRB 100504A: Fermi GBM observation
  80. An SGR-like burst from the magnetar 1E 1841-04.5 in Kes 73
  81. GRB 100504A: Swift/UVOT Observations
  82. GRB 100418A: Flattening of the Swift/UVOT Optical Light Curve
  83. GRB 100504A: Swift-XRT refined analysis
  84. GRB 100504A: Enhanced Swift-XRT position
  85. GRB 100504A: GROND Upper limits
  86. GRB 100504A: Swift-BAT refined analysis
  87. GRB 100504A: SARA-South Upper Limit
  88. GRB 100503A: Fermi GBM detection
  89. GRB 100504A: UVOT-enhanced XRT position
  90. GRB 100504A: Swift detection of a burst
  91. Swift-BAT trigger 421072 is not astrophyical
  92. INTEGRAL observations of Swift GRB trigger 421072
  93. GRB100423A : Suzaku WAM observation of the prompt emission
  94. Trigger 421072: Possible Swift detection of a GRB or transient
  95. GRB 100420A: EVLA radio observations
  96. GRB 100420A: Gemini discovery of infrared afterglow
  97. GRB 100423A: xinglong TNT optical upper limit
  98. GRB 100420A: Terskol optical upper limit
  99. GRB 100427A: Swift XRT and UVOT Upper Limits
  100. GRB 100427A: Fermi GBM detection

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