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

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