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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 100805A: Xinglong TNT optical observation
  2. GRB 100805A: Early RAPTOR Observations
  3. GRB 100805A: ROTSE-III Optical detection
  4. GRB 100805A: Swift/UVOT Observations of the Optical Afterglow
  5. GRB 100802A: WIYN observations
  6. GRB 100805A: IAC80 BVR-band observations
  7. Swift-BAT trigger 430975 is not a burst
  8. GRB 100805A: Swift-BAT refined analysis
  9. GRB 100805A: Swift-XRT Refined Analysis
  10. GRB 100805A: GRAS 002 optical observations
  11. Trigger 430975: Swift detection of a possible burst
  12. GRB 100805A: I-band detection from 1.23m CAHA telescope.
  13. GRB 100805A: Enhanced Swift-XRT position
  14. GRB 100805A: Liverpool Telescope afterglow observations
  15. GRB 100805A: Further P60 Monitoring
  16. GRB 100805A: P60 Optical Afterglow Candidate
  17. GRB 100805A: Enhanced Swift-XRT position
  18. GRB 100805A: ROTSE-III Optical Limits
  19. GRB 100805A: Swift detection of a burst with an optical counterpart
  20. GRB 100802A: Fermi GBM observation
  21. GRB 100728B: optical photometry of ISON-NM
  22. GRB 100713A: second epoch Maidanak optical observation
  23. GRB 100713A: CrAO optical limits
  24. GRB 100802A: NOT optical observation
  25. GRB100802A: MITSuME optical upper limits
  26. GRB 100802A: P60 Observations
  27. GRB 100802A: XRT refined analysis
  28. GRB 100802A: Swift/UVOT Possible Optical Afterglow
  29. GRB 100728A: Suzaku WAM observation of the prompt emission
  30. GRB 100802A: Enhanced Swift-XRT position
  31. GRB 100802A: Swift-BAT refined analysis
  32. GRB 100802A: Liverpool Telescope observations
  33. GRB 100802A: ROTSE-III Optical Limits
  34. GRB 100802A: Possible Swift/UVOT Detection of Optical Afterglow
  35. GRB 100802A: Swift detection of a burst
  36. GRB 100725B: TELMA optical observation
  37. GRB 100728B: Swift/UVOT Observations (correction to GCN 11028)
  38. GRB 100728B: Swift/UVOT Observations (correction)
  39. GRB 100728B - NOT optical observation
  40. GRB 100728B: Swift/UVOT Observations
  41. GRB 100728B: Lick Observations
  42. GRB 100728B: Continued KAIT observations
  43. GRB 100728B, Swift-BAT refined analysis
  44. GRB 100728B: Swift-XRT Refined Analysis
  45. Konus-Wind observation of GRB 100728A
  46. GRB 100728A: GROND Detection of the NIR Afterglow Candidate
  47. GRB 100727A: Swift/UVOT Upper Limits
  48. GRB 100728A, Swift-BAT refined analysis
  49. GRB 100728B: Enhanced Swift-XRT position
  50. GRB 100728A: Swift/UVOT Upper Limits
  51. GRB 100728B: Fermi GBM observation
  52. GRB 100728A: Swift-XRT refined analysis
  53. GRB 100728B: GROND Detection of the NIR Afterglow
  54. GRB 100728B: optical detection
  55. GRB 100728B: Skynet/PROMPT Detections (correction)
  56. GRB 100728B: KAIT optical afterglow detection (correction)
  57. GRB 100728B: Swift detection of a burst with an optical counterpart
  58. GRB 100728A: Skynet/PROMPT Detections
  59. GRB 100728A: KAIT optical afterglow detection
  60. GRB 100728A: Fermi GBM observation
  61. GRB 100728A: Enhanced Swift-XRT position
  62. GRB 100728A: Swift detection of a burst
  63. GRB 100727A: Swift XRT refined analysis
  64. GRB 100727A: Fermi GBM observation
  65. GRB 100727A, Swift-BAT refined analysis
  66. GRB 100727A: Enhanced Swift-XRT position
  67. GRB100727A: MOA optical upper limit
  68. GRB 100727A: Swift detection of a burst
  69. GRB100725B: MITSuME optical upper limits
  70. GRB 100724B: AGILE/GRID analysis
  71. GRB 100724B: Suzaku WAM observation of the prompt emission
  72. GRB 100724B: gamma-ray detection by AGILE
  73. GRB 100725B: Swift-BAT refined analysis
  74. GRB 100725B: refined XRT analysis
  75. GRB 100725A: GROND upper limits
  76. GRB 100725B: Swift/UVOT Upper Limits
  77. GRB 100725A: Swift/UVOT Upper Limits
  78. GRB 100725A: Swift-BAT refined analysis
  79. GRB 100725A: Swift XRT refined analysis
  80. GRB 100725B: Enhanced Swift-XRT position
  81. GRB 100725A: Enhanced Swift-XRT position
  82. GRB100725B: Faulkes Telescope North observations
  83. GRB 100725B: Swift detection of a burst
  84. GRB100725A Faulkes Telescope South observations
  85. Konus-Wind observation of GRB 100724B
  86. GRB 100725A: Prompt enhanced Swift-XRT position
  87. GRB 100725A: Swift detection of a burst
  88. GRB 100724B: Fermi LAT and GBM analysis
  89. GRB 100724B: Fermi GBM detection
  90. GRB 100724A: Swift/BAT spectral lag results
  91. GRB 100724A: Swift XRT refined analysis
  92. GRB 100724A: Enhanced Swift-XRT position
  93. GRB 100724A: Swift/UVOT observations
  94. GRB 100724A: Swift-BAT refined analysis
  95. GRB 100724A: X-shooter redshift
  96. GRB 100724A: fading afterglow seen with GROND
  97. GRB 100724A, GROND detection of an afterglow candidate
  98. GRB 100724A: Swift detection of a burst
  99. GRB 100614A: 10.4-m GTC deep-optical limit
  100. GRB 100722A: Fermi GBM detection

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