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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 100513A: Swift XRT refined analysis
  2. GRB 100513A: Swift-BAT refined analysis
  3. GRB 100513A: Gemini/GMOS Spectroscopic Redshift
  4. GRB 100513A: Enhanced Swift-XRT position
  5. GRB 100513A: Lick observations and R-band dropout
  6. GRB 100513A: PAIRITEL continued observations and confirmation of fading
  7. GRB 100513A: SARA-N Upper Limit
  8. GRB 100513A: PAIRITEL NIR afterglow candidate
  9. GRB 100513A: Swift detection of a burst
  10. GRB 100510A: Fermi GBM detection/observation
  11. GRB 100511A: Fermi GBM detection/observation
  12. GRB 100511A: Super-LOTIS early observations
  13. Swift-BAT trigger 421695 is likely not astrophysical
  14. GRB100504A: Optical upper limits at IAO
  15. GRB 100510A: MAXI/GSC detection
  16. GRB 100511A, RIMOTS optical upper limits
  17. Trigger 421695: Swift detection of a possible burst
  18. GRB100508A: Further Swift/UVOT Observations
  19. GRB100503A: Suzaku WAM observation of the prompt emission
  20. GRB 100508A: GROND Detection of the optical afterglow
  21. GRB 100508A: Swift-XRT Refined analysis
  22. GRB 100508A: Swift-BAT refined analysis
  23. GRB 100508A: Enhanced Swift-XRT position
  24. GRB100508A: Swift/UVOT Detection of the Afterglow
  25. GRB 100508A: ROTSE-III Optical Limits
  26. GRB 100508A: Swift detection of a burst
  27. GRB 100418A: Keck imaging
  28. GRB 100418A: RTT150 optical observations
  29. Fermi Gamma-ray Burst Monitor trigger 294712621 is not a GRB
  30. Swift-BAT refined analysis of trigger 421262
  31. GRB 100504A: Fermi GBM observation
  32. An SGR-like burst from the magnetar 1E 1841-04.5 in Kes 73
  33. GRB 100504A: Swift/UVOT Observations
  34. GRB 100418A: Flattening of the Swift/UVOT Optical Light Curve
  35. GRB 100504A: Swift-XRT refined analysis
  36. GRB 100504A: Enhanced Swift-XRT position
  37. GRB 100504A: GROND Upper limits
  38. GRB 100504A: Swift-BAT refined analysis
  39. GRB 100504A: SARA-South Upper Limit
  40. GRB 100503A: Fermi GBM detection
  41. GRB 100504A: UVOT-enhanced XRT position
  42. GRB 100504A: Swift detection of a burst
  43. Swift-BAT trigger 421072 is not astrophyical
  44. INTEGRAL observations of Swift GRB trigger 421072
  45. GRB100423A : Suzaku WAM observation of the prompt emission
  46. Trigger 421072: Possible Swift detection of a GRB or transient
  47. GRB 100420A: EVLA radio observations
  48. GRB 100420A: Gemini discovery of infrared afterglow
  49. GRB 100423A: xinglong TNT optical upper limit
  50. GRB 100420A: Terskol optical upper limit
  51. GRB 100427A: Swift XRT and UVOT Upper Limits
  52. GRB 100427A: Fermi GBM detection
  53. GRB 100424a. Radio observations
  54. GRB 100418A: RTT150 optical observations
  55. GRB 100427A detected in ground analysis of Swift BAT data
  56. GRB 100414A : EVLA Radio Detection
  57. GRB 100414A : WSRT Radio Detection
  58. Konus-Wind observation of GRB 100423A
  59. GRB 100423A: CrAO optical observations
  60. GRB 100418A: Terskol optical observations
  61. GRB 100424A: CrAO optical observations
  62. GRB 100424A: NIR Afterglow Confirmation
  63. GRB 100425A: Swift XRT refined analysis
  64. GRB 100424A: Gemini/NIRI H-band observations
  65. GRB100425A: Swift/UVOT Upper Limits
  66. GRB 100424A: Swift/UVOT Upper Limits
  67. GRB 100424A: Liverpool Telescope Upper Limits
  68. GRB 100425A: Enhanced Swift-XRT position
  69. GRB 100425A: Swift-BAT refined analysis
  70. GRB 100425A: VLT/X-shooter redshift
  71. GRB 100425A: GROND afterglow observation
  72. GRB 100424A: Gemini/NIRI Candidate Afterglow
  73. GRB 100424A: D50 optical limits
  74. GRB 100425A: candidate optical afterglow from the VLT
  75. GRB100424A: MITSuME optical upper limits
  76. GRB100423A: MITSuME optical upper limits
  77. GRB 100424A : Lulin early z'-band upper limit
  78. GRB 100424A: GROND Upper Limits
  79. GRB 100424A: PAIRITEL NIR Upper Limits
  80. GRB 100424A: Swift-XRT refined analysis
  81. GRB 100425A: Swift detection of a burst
  82. GRB 100424A: WHT z-band observations
  83. GRB 100424A: NOT optical observations
  84. GRB 100424A, Swift-BAT refined analysis
  85. GRB 100424A: Enhanced Swift-XRT position
  86. GRB 100424A: Prompt enhanced Swift-XRT position.
  87. GRB 100424A: Swift detection of a burst
  88. GRB 100420A: GRT Optical Observation
  89. GRB 100418A: ROVOR optical measurements at 35 hours
  90. Swift-BAT refined analysis of trigger 420256
  91. Swift Trigger 420256: D50 optical limits
  92. GRB 100418A: Possible Evidence for a Supernova
  93. GRB 100420A: Swift-BAT refined analysis
  94. GRB 100423B: Fermi GBM detection
  95. GRB 100423A: Swift-BAT refined analysis
  96. Swift Trigger 420256: IAC80 R-band observations
  97. Swift Trigger 420256: BOOTES-2 observations
  98. Swift Trigger 420256: ROTSE-III Optical Limits
  99. Trigger 420256: Swift detection of a possible GRB
  100. GRB 100423A: Skynet/PROMPT Detections

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