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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 100420A: Terskol optical upper limit
  2. GRB 100427A: Swift XRT and UVOT Upper Limits
  3. GRB 100427A: Fermi GBM detection
  4. GRB 100424a. Radio observations
  5. GRB 100418A: RTT150 optical observations
  6. GRB 100427A detected in ground analysis of Swift BAT data
  7. GRB 100414A : EVLA Radio Detection
  8. GRB 100414A : WSRT Radio Detection
  9. Konus-Wind observation of GRB 100423A
  10. GRB 100423A: CrAO optical observations
  11. GRB 100418A: Terskol optical observations
  12. GRB 100424A: CrAO optical observations
  13. GRB 100424A: NIR Afterglow Confirmation
  14. GRB 100425A: Swift XRT refined analysis
  15. GRB 100424A: Gemini/NIRI H-band observations
  16. GRB100425A: Swift/UVOT Upper Limits
  17. GRB 100424A: Swift/UVOT Upper Limits
  18. GRB 100424A: Liverpool Telescope Upper Limits
  19. GRB 100425A: Enhanced Swift-XRT position
  20. GRB 100425A: Swift-BAT refined analysis
  21. GRB 100425A: VLT/X-shooter redshift
  22. GRB 100425A: GROND afterglow observation
  23. GRB 100424A: Gemini/NIRI Candidate Afterglow
  24. GRB 100424A: D50 optical limits
  25. GRB 100425A: candidate optical afterglow from the VLT
  26. GRB100424A: MITSuME optical upper limits
  27. GRB100423A: MITSuME optical upper limits
  28. GRB 100424A : Lulin early z'-band upper limit
  29. GRB 100424A: GROND Upper Limits
  30. GRB 100424A: PAIRITEL NIR Upper Limits
  31. GRB 100424A: Swift-XRT refined analysis
  32. GRB 100425A: Swift detection of a burst
  33. GRB 100424A: WHT z-band observations
  34. GRB 100424A: NOT optical observations
  35. GRB 100424A, Swift-BAT refined analysis
  36. GRB 100424A: Enhanced Swift-XRT position
  37. GRB 100424A: Prompt enhanced Swift-XRT position.
  38. GRB 100424A: Swift detection of a burst
  39. GRB 100420A: GRT Optical Observation
  40. GRB 100418A: ROVOR optical measurements at 35 hours
  41. Swift-BAT refined analysis of trigger 420256
  42. Swift Trigger 420256: D50 optical limits
  43. GRB 100418A: Possible Evidence for a Supernova
  44. GRB 100420A: Swift-BAT refined analysis
  45. GRB 100423B: Fermi GBM detection
  46. GRB 100423A: Swift-BAT refined analysis
  47. Swift Trigger 420256: IAC80 R-band observations
  48. Swift Trigger 420256: BOOTES-2 observations
  49. Swift Trigger 420256: ROTSE-III Optical Limits
  50. Trigger 420256: Swift detection of a possible GRB
  51. GRB 100423A: Skynet/PROMPT Detections
  52. GRB 100423A: GROND discovery of afterglow
  53. GRB 100423A: Swift detection of a burst
  54. Radio afterglow detection of GRB 100418A with the EVLA
  55. GRB 100414A: Radio Afterglow Detection with the Expanded VLA
  56. GRB 100418A: Continued PAIRITEL NIR Observations
  57. GRB 100418A: WSRT Radio Detection
  58. GRB100418A: REM possible afterglow detection
  59. GRB 100418A: Continuing Swift/UVOT Observations
  60. GRB 100418A: further GROND observations and light curve fit
  61. GRB 100418A: RTT150 optical observations
  62. GRB100420A: MITSuME optical upper limits
  63. GRB 100414A: CFHT optical observations
  64. GRB 100420A: Swift/UVOT Upper Limits
  65. GRB 100420A: XRT refined analysis
  66. GRB 100420A: Enhanced Swift-XRT position
  67. GRB 100418A: SARA second epoch
  68. GRB 100420A: SARA Upper Limits
  69. GRB 100418A: RTT150 observations during the optical afterglow maximum
  70. GRB 100418A: optical observations
  71. GRB 100418A: MASTER-Net optical observations
  72. GRB 100414A: Confirmation of the X-ray afterglow
  73. GRB 100418A: VLT optical observations
  74. GRB 100418A: SMA submm detection
  75. GRB 100420A: ROTSE-III Optical Limits
  76. GRB 100420A: Swift detection of a burst
  77. GRB 100418A PAIRITEL NIR Observations
  78. GRB 100418A: ROVOR optical afterglow detection
  79. GRB 100418A: Swift/UVOT Observations
  80. GRB 100418A: Gemini-N redshift confirmation
  81. GRB 100413A: GMRT observation of radio afterglow
  82. GRB 100418A: Swift-XRT Refined Analysis
  83. GRB 100418A: host galaxy detection in the SDSS
  84. GRB100418A: VLT/X-shooter redshift and photometry
  85. GRB 100418A: SARA observations
  86. GRB100414A: SAO RAS optical observations
  87. GRB 100418A: GROND observations; missing author list added
  88. GRB 100418A: GROND observations
  89. GRB 100418A: Swift-BAT refined analysis
  90. GRB 100418A: Enhanced Swift-XRT position
  91. GRB 100418A: ROTSE-III Optical Limits
  92. GRB 100418A: Swift detection of a burst with a possible optical afterglow
  93. GRB 100413A: Radio Afterglow Detection with the EVLA
  94. GRB 100414A: Suzaku WAM observation of the prompt emission
  95. GRB 100414A: Swift/UVOT Observations
  96. GRB 100414A: Gemini-N observation (correction)
  97. GRB 100414A: GROND Detection of the Optical Afterglow
  98. GRB 100414A: Gemini-N candidate and redshift
  99. GRB 100414A: Enhanced Swift-XRT position of candidate afterglow
  100. GRB 100413A: Suzaku WAM observation of the prompt emission

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