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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. GRB100807A: R band observations
  2. GRB100823A : MOA optical observation
  3. GRB 100823A: Candidate IR afterglow
  4. GRB 100823A: Swift XRT refined analysis
  5. GRB 100823A: VLT/X-Shooter spectroscopy
  6. GRB 100823A - second epoch WHT observations
  7. GRB 100823A: TNG NIR observations
  8. GRB 100823: 1.5m OSN I-band observations
  9. GRB 100823A: Swift/UVOT Upper Limits
  10. GRB 100823A: WHT observations
  11. GRB 100823A: Swift-BAT refined analysis
  12. GRB 100823A: Enhanced Swift-XRT position
  13. GRB 100823A: Swift detection of a burst
  14. GRB 100814A: Suzaku WAM observation of the prompt emission
  15. GRB 100814A: ISON-NM optical observations
  16. IBAS Alert n. 6057 is not due to a GRB
  17. EVLA radio afterglow detection of GRB 100814A
  18. GRB 100814B: Fermi GBM detection
  19. GRB 100814A: optical observations
  20. GRB 100816A: Fermi GBM observation (correction to GCN 11124)
  21. Konus-Wind observation of GRB 100816A
  22. GRB100816A: MITSuME optical upper limits
  23. GRB 100816A: 10.4-m GTC redshift confirmation
  24. GRB 100816A: Fermi GBM observation
  25. GRB 100816A: VLT and Gemini-N revised redshift
  26. GRB 100814A : Liverpool Telescope Observations
  27. GRB 100814A: NOT optical observations
  28. GRB 100816A: NOT optical observations
  29. Konus-Wind observation of GRB 100814A
  30. GRB 100814A : Lulin optical observation
  31. GRB 100816A : Lulin r'-band observation
  32. GRB 100816A: Gemini-N spectroscopy
  33. GRB 100816A: Swift UVOT Observations
  34. GRB100816A Swift-XRT refined analysis
  35. GRB 100816A: Swift-BAT spectral lag results
  36. GRB 100816A: 1.23m CAHA optical observations
  37. GRB 100816A, Swift-BAT refined analysis
  38. GRB 100816A: Enhanced Swift-XRT position
  39. GRB 100816A: Gemini-N imaging
  40. GRB 100816A: CQUEAN riz-band Detection, Host Galaxy?
  41. GRB100814A - interesting UVOT lightcurve.
  42. GRB 100816A: TAROT Calern observatory optical detection
  43. GRB 100816A: MASTER Optical Limits
  44. GRB100816A: TNG optical afterglow confirmation.
  45. GRB 100816A: ROTSE-III Optical Limits
  46. GRB 100816A: Swift detection of a possibly short burst with optical afterglow
  47. Swift-BAT trigger 431756 is not a burst
  48. Swift/UVOT observations of GRB100814A - title correction to GCN 11097
  49. GRB 100814A: Fermi GBM observation
  50. GRB 100814A: Submm observations from APEX
  51. Swift/UVOT Observations of GRB100814A - a clearer table.
  52. GRB 100814A: Swift-XRT refined analysis
  53. Swift/UVOT observations of GRB100814A
  54. GRB 100814A, Swift-BAT refined analysis
  55. GRB 100814A: CQUEAN r- and i-band Observation
  56. GRB 100814A: Enhanced Swift-XRT position
  57. GRB 100814A: GROND Detection of the Optical/NIR Afterglow
  58. GRB 100814A: IAC80 R-band observations
  59. GRB100814A: Magellan Echellette Observations
  60. GRB 100814A: Swift UVOT observations of the optical afterglow
  61. GRB 100814A: Swift detection of a burst with an optical afterglow
  62. GRB 100814A: ROTSE-III Detection of Optical Counterpart
  63. Swift-BAT trigger 431582 likely is IGR J17464-2811
  64. GRB 100805A: the 4-th epoch of SAO RAS optical observations
  65. GRB 100805A: optical observation in CrAO (correction to the GCN 11077 and second epoch)
  66. GRB 100802A: further NOT observation
  67. GRB 100805A: Swift/UVOT Observations of a Possible Late-Time Brightening
  68. GRB 100807A: P200 Infrared Observations
  69. GRB 100805A: the 3-rd epoch of SAO RAS optical observations
  70. GRB100807A: optical observation in CrAO
  71. GRB 100805A: optical observation in CrAO
  72. GRB 100805A: 2-nd epoch of SAO RAS optical observations
  73. GRB100807A: MITSuME optical upper limits
  74. GRB 100807A: Swift XRT refined analysis
  75. GRB 100807A: P60 Optical Afterglow Discovery
  76. GRB 100807A: Swift/UVOT Upper Limits
  77. GRB 100805A: SAO RAS optical observations
  78. GRB 100807A: Enhanced Swift-XRT position
  79. GRB 100807A: Swift-BAT refined analysis
  80. GRB 100807A: ROTSE-III Optical Limits
  81. GRB 100807A: Swift detection of a burst
  82. GRB 100805A: IAC80 and 1.5m OSN optical observations
  83. GRB 100805A: Xinglong TNT optical observation
  84. GRB 100805A: Early RAPTOR Observations
  85. GRB 100805A: ROTSE-III Optical detection
  86. GRB 100805A: Swift/UVOT Observations of the Optical Afterglow
  87. GRB 100802A: WIYN observations
  88. GRB 100805A: IAC80 BVR-band observations
  89. Swift-BAT trigger 430975 is not a burst
  90. GRB 100805A: Swift-BAT refined analysis
  91. GRB 100805A: Swift-XRT Refined Analysis
  92. GRB 100805A: GRAS 002 optical observations
  93. Trigger 430975: Swift detection of a possible burst
  94. GRB 100805A: I-band detection from 1.23m CAHA telescope.
  95. GRB 100805A: Enhanced Swift-XRT position
  96. GRB 100805A: Liverpool Telescope afterglow observations
  97. GRB 100805A: Further P60 Monitoring
  98. GRB 100805A: P60 Optical Afterglow Candidate
  99. GRB 100805A: Enhanced Swift-XRT position
  100. GRB 100805A: ROTSE-III Optical Limits

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