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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 100816A: TAROT Calern observatory optical detection
  2. GRB 100816A: MASTER Optical Limits
  3. GRB100816A: TNG optical afterglow confirmation.
  4. GRB 100816A: ROTSE-III Optical Limits
  5. GRB 100816A: Swift detection of a possibly short burst with optical afterglow
  6. Swift-BAT trigger 431756 is not a burst
  7. Swift/UVOT observations of GRB100814A - title correction to GCN 11097
  8. GRB 100814A: Fermi GBM observation
  9. GRB 100814A: Submm observations from APEX
  10. Swift/UVOT Observations of GRB100814A - a clearer table.
  11. GRB 100814A: Swift-XRT refined analysis
  12. Swift/UVOT observations of GRB100814A
  13. GRB 100814A, Swift-BAT refined analysis
  14. GRB 100814A: CQUEAN r- and i-band Observation
  15. GRB 100814A: Enhanced Swift-XRT position
  16. GRB 100814A: GROND Detection of the Optical/NIR Afterglow
  17. GRB 100814A: IAC80 R-band observations
  18. GRB100814A: Magellan Echellette Observations
  19. GRB 100814A: Swift UVOT observations of the optical afterglow
  20. GRB 100814A: Swift detection of a burst with an optical afterglow
  21. GRB 100814A: ROTSE-III Detection of Optical Counterpart
  22. Swift-BAT trigger 431582 likely is IGR J17464-2811
  23. GRB 100805A: the 4-th epoch of SAO RAS optical observations
  24. GRB 100805A: optical observation in CrAO (correction to the GCN 11077 and second epoch)
  25. GRB 100802A: further NOT observation
  26. GRB 100805A: Swift/UVOT Observations of a Possible Late-Time Brightening
  27. GRB 100807A: P200 Infrared Observations
  28. GRB 100805A: the 3-rd epoch of SAO RAS optical observations
  29. GRB100807A: optical observation in CrAO
  30. GRB 100805A: optical observation in CrAO
  31. GRB 100805A: 2-nd epoch of SAO RAS optical observations
  32. GRB100807A: MITSuME optical upper limits
  33. GRB 100807A: Swift XRT refined analysis
  34. GRB 100807A: P60 Optical Afterglow Discovery
  35. GRB 100807A: Swift/UVOT Upper Limits
  36. GRB 100805A: SAO RAS optical observations
  37. GRB 100807A: Enhanced Swift-XRT position
  38. GRB 100807A: Swift-BAT refined analysis
  39. GRB 100807A: ROTSE-III Optical Limits
  40. GRB 100807A: Swift detection of a burst
  41. GRB 100805A: IAC80 and 1.5m OSN optical observations
  42. GRB 100805A: Xinglong TNT optical observation
  43. GRB 100805A: Early RAPTOR Observations
  44. GRB 100805A: ROTSE-III Optical detection
  45. GRB 100805A: Swift/UVOT Observations of the Optical Afterglow
  46. GRB 100802A: WIYN observations
  47. GRB 100805A: IAC80 BVR-band observations
  48. Swift-BAT trigger 430975 is not a burst
  49. GRB 100805A: Swift-BAT refined analysis
  50. GRB 100805A: Swift-XRT Refined Analysis
  51. GRB 100805A: GRAS 002 optical observations
  52. Trigger 430975: Swift detection of a possible burst
  53. GRB 100805A: I-band detection from 1.23m CAHA telescope.
  54. GRB 100805A: Enhanced Swift-XRT position
  55. GRB 100805A: Liverpool Telescope afterglow observations
  56. GRB 100805A: Further P60 Monitoring
  57. GRB 100805A: P60 Optical Afterglow Candidate
  58. GRB 100805A: Enhanced Swift-XRT position
  59. GRB 100805A: ROTSE-III Optical Limits
  60. GRB 100805A: Swift detection of a burst with an optical counterpart
  61. GRB 100802A: Fermi GBM observation
  62. GRB 100728B: optical photometry of ISON-NM
  63. GRB 100713A: second epoch Maidanak optical observation
  64. GRB 100713A: CrAO optical limits
  65. GRB 100802A: NOT optical observation
  66. GRB100802A: MITSuME optical upper limits
  67. GRB 100802A: P60 Observations
  68. GRB 100802A: XRT refined analysis
  69. GRB 100802A: Swift/UVOT Possible Optical Afterglow
  70. GRB 100728A: Suzaku WAM observation of the prompt emission
  71. GRB 100802A: Enhanced Swift-XRT position
  72. GRB 100802A: Swift-BAT refined analysis
  73. GRB 100802A: Liverpool Telescope observations
  74. GRB 100802A: ROTSE-III Optical Limits
  75. GRB 100802A: Possible Swift/UVOT Detection of Optical Afterglow
  76. GRB 100802A: Swift detection of a burst
  77. GRB 100725B: TELMA optical observation
  78. GRB 100728B: Swift/UVOT Observations (correction to GCN 11028)
  79. GRB 100728B: Swift/UVOT Observations (correction)
  80. GRB 100728B - NOT optical observation
  81. GRB 100728B: Swift/UVOT Observations
  82. GRB 100728B: Lick Observations
  83. GRB 100728B: Continued KAIT observations
  84. GRB 100728B, Swift-BAT refined analysis
  85. GRB 100728B: Swift-XRT Refined Analysis
  86. Konus-Wind observation of GRB 100728A
  87. GRB 100728A: GROND Detection of the NIR Afterglow Candidate
  88. GRB 100727A: Swift/UVOT Upper Limits
  89. GRB 100728A, Swift-BAT refined analysis
  90. GRB 100728B: Enhanced Swift-XRT position
  91. GRB 100728A: Swift/UVOT Upper Limits
  92. GRB 100728B: Fermi GBM observation
  93. GRB 100728A: Swift-XRT refined analysis
  94. GRB 100728B: GROND Detection of the NIR Afterglow
  95. GRB 100728B: optical detection
  96. GRB 100728B: Skynet/PROMPT Detections (correction)
  97. GRB 100728B: KAIT optical afterglow detection (correction)
  98. GRB 100728B: Swift detection of a burst with an optical counterpart
  99. GRB 100728A: Skynet/PROMPT Detections
  100. GRB 100728A: KAIT optical afterglow detection

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