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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 141028A: LCOGTN observations
  2. GRB 141029A Tiled Swift observations
  3. GRB 141028A: VLT/X-shooter redshift of z=2.33
  4. GRB141028A: Gemini-North redshift
  5. GRB 141029A: MAXI/GSC detection
  6. GRB 141028A: RATIR Optical and NIR Observations
  7. GRB 141028A: Swift/UVOT Detection
  8. GRB 141028A: Swift/XRT detection of the X-ray afterglow
  9. GRB 141028A: GROND Afterglow confirmation (MASTER source)
  10. GRB 141020A: Continued Mondy Observations, optical upper limit
  11. IPN triangulation of GRB 141028A
  12. GRB 141026A: IRAM 30m millimetre observations
  13. GRB 141028A Tiled Swift observations
  14. GRB 141028A: MASTER OT candidate detection
  15. GRB 141028A: Fermi GBM detection
  16. GRB 141026A: Continued RATIR Optical and NIR Observations
  17. GRB 141028A: Fermi-LAT detection
  18. GRB 141026A: GTC spectroscopy
  19. GRB 141026A: Skynet PROMPT-CTIO/Yerkes-41 Observations
  20. GRB 141026A: SAO RAS Zeiss-1000 observations
  21. GRB 141026A: Continued RATIR Optical and NIR Observations
  22. GRB 141026A: Swift/UVOT Upper Limits
  23. GRB 141004A: Continued RATIR Late Time Optical and NIR Observations
  24. GRB 141026A: Continued RATIR Optical and NIR Observations, Afterglow Detection
  25. GRB 141026A: Swift-XRT refined Analysis
  26. GRB 141026A: Swift-BAT refined analysis
  27. Fermi Gamma-ray Burst Monitor trigger 141026452 is not a GRB
  28. GRB 141026A: MASTER early optical observations
  29. GRB 141026A: Enhanced Swift-XRT position
  30. GRB141026A: Deep P200 optical imaging
  31. GRB 141026A: 1.23m CAHA I-band observations
  32. GRB 141026A: GROND observations
  33. GRB 141026A: RATIR Optical Observations
  34. GRB 141026A: P60 early observations
  35. GRB 141026A: Swift detection of a burst
  36. Fermi Gamma-ray Burst Monitor trigger 141025734 is not a GRB
  37. GRB 141020A: AAO optical upper limit
  38. GRB 141020A: Khureltogot optical upper limit
  39. GRB141022A: Fermi GBM Detection
  40. GRB141022B: Fermi GBM Detection
  41. GRB 141022A: Swift/UVOT Upper Limits
  42. GRB 141020A: Mondy optical observations
  43. GRB 141022A: Swift-BAT refined analysis
  44. GRB 141022A: Swift-XRT refined Analysis
  45. GRB141015A iTelescope observation
  46. GRB 141022A: GROND Detection of a possible Optical Afterglow Candidate
  47. GRB 141022A: Swift detection of a burst
  48. GRB 141004A: RATIR Late Time Optical and NIR Observations
  49. GRB 141004A: La Palma late-time observations and possible brightening
  50. GRB 141020A: Swift-BAT refined analysis
  51. GRB 141020A: Swift-XRT refined Analysis
  52. GRB 141020A: 1.4 GHZ observation
  53. GRB 141020A: Swift/UVOT Detection
  54. GRB 141020A: Enhanced Swift-XRT position
  55. GRB 141020B: MAXI/GSC detection
  56. Konus-Wind observation of GRB 141017A
  57. GRB 141020A: Swift detection of a burst with an optical counterpart
  58. GRB 141017A, Swift-BAT refined analysis
  59. GRB 141017A: GROND Afterglow Confirmation
  60. GRB 141015A: Swift-XRT afterglow confirmation and refined Analysis
  61. GRB 141017A: Swift/UVOT Detection
  62. GRB 141015A: MITSuME Akeno upper limits
  63. GRB 141017A: Swift-XRT refined Analysis
  64. GRB 141017A: Enhanced Swift-XRT position
  65. GRB 141017A: Zadko observatory - Gingin optical observations
  66. GRB 141017A: Swift detection of a burst
  67. GRB 141015A: Swift/UVOT Upper Limits
  68. GRB 141015A: MITSuME Okayama upper limits
  69. GRB 141015A: Swift-BAT refined analysis
  70. GRB 141015A: LCO-McDonald observations
  71. GRB 141015A: RATIR Optical Upper Limits
  72. GRB 141015A: Enhanced Swift-XRT position
  73. GRB 141015A: Super-LOTIS early observations
  74. GRB 141015A: ISON-NM early optical observations
  75. GRB 141015A: Swift/XRT localization
  76. GRB 141015A: Swift detection of a burst
  77. Fermi Gamma-ray Burst Monitor trigger 141014781 is not a GRB
  78. Konus-Wind observation of GRB 141011A
  79. IPN Triangulation of GRB 141011A (short/hard)
  80. GRB 141011A: Fermi GBM detection
  81. Trigger 614903: Swift detection of IGR J17544-2619
  82. GRB 141005A: iTelescope.Net T21 Optical Observation
  83. GRB141004A: Host galaxy redshift form GTC
  84. GRB 141005A: Additional P60 imaging and afterglow confirmation
  85. GRB 141004A: Fermi GBM observation
  86. GRB 141004A: GROND observations
  87. GRB 141005A: GROND observations
  88. Konus-Wind observation of GRB 141005A
  89. GRB 141004A: Swift-XRT refined Analysis
  90. GRB 141005A: Swift-XRT refined Analysis
  91. GRB 141005A: Swift/UVOT Upper Limits
  92. GRB 141005A: Swift-BAT refined analysis
  93. GRB 141004A: Swift-BAT refined analysis
  94. GRB141004A: NOT imaging and spectroscopy
  95. GRB 141004A: Swift/UVOT Detection
  96. GRB 141005A: Fermi GBM Detection
  97. GRB 141005A: Enhanced Swift-XRT position
  98. GRB 141004A: RATIR Optical Observations
  99. GRB 141004A: Monte Agliale Observatory optical observations
  100. GRB 141005A: RATIR Optical Observations

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