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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 221115B: CALET Gamma-Ray Burst Monitor detection
  2. GRB 221114A: CALET Gamma-Ray Burst Monitor detection
  3. GRB 221118A: Fermi GBM Final Real-time Localization
  4. GRB 221115B: LCOGT Optical Upper Limits
  5. Correction to GCN 32646 (GRB 221009A (Swift J1913.1+1946): MeerLICHT observations)
  6. GRB 221115B : MeerLICHT upper limits
  7. GRB 221115A: Fermi GBM detection
  8. GRB 221115B: Swift/BAT-GUANO arcminute localization
  9. GRB 221115A: Swift/BAT-GUANO detection
  10. GRB 221110A: GRANDMA observations
  11. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 November 9
  12. GRB 221112A: Detection by GRBAlpha
  13. GRB 221112A: Fermi GBM Final Real-time Localization
  14. GRB 221110A: COATLI Second-Epoch Upper Limits
  15. GRB 221009A: GRANDMA/Kilonova-Catcher observations
  16. GRB 221110A: GMG upper limit
  17. GRB 221110A: Swift/UVOT Detection and Corrected UVOT Position
  18. GRB 221110A: Swift-BAT refined analysis
  19. GRB 221110A: Swift-XRT refined Analysis
  20. GRB 221110A: Enhanced Swift-XRT position
  21. GRB 221110A: VLT/X-shooter redshift
  22. GRB 221110A: COATLI Afterglow detection
  23. GRB 221110A: LCOGT Optical Afterglow Detection
  24. GRB 221110A: Swift detection of a burst with an optical counterpart
  25. Swift GRB221110.10: Global MASTER-Net OT detection
  26. Swift GRB221110.10: Global MASTER-Net observations report
  27. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  28. GRB 221009A: Hubble Space Telescope observations
  29. GRB 221104A: Fermi GBM Final Localization
  30. GRB 221108A: Fermi GBM Final Localization
  31. GRB 221107A: Fermi GBM Observation
  32. GRB 221107A: Detection by GRBAlpha
  33. GRB 221009A: Extended Bad Time Intervals for Fermi LAT data
  34. GRB 221107A: Swift/BAT-GUANO detection outside the coded FOV
  35. IceCube-221104A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 221107A: Fermi GBM Final Localization
  37. Correction to GCN 32852 (GRB 221009A: SARA-RM 1m Optical Afterglow Detection)
  38. IceCube Alert 221104.26: Global MASTER-Net observations report
  39. Fermi-LAT gamma-ray observations of IceCube-221104A
  40. IceCube-221104A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 221029A: CALET Gamma-Ray Burst Monitor detection
  42. High-precision position of the compact radio counterpart to GRB221009A
  43. GRB 221028A: GRANDMA observations
  44. GRB 221027B: GRANDMA observations
  45. GRB 221028A: Detection by VZLUSAT-2
  46. GRB 221029A: Fermi GBM observation
  47. GRB 221027C: AstroSat CZTI detection
  48. Konus-Wind detection of GRB 221022C
  49. GRB 221029A: Fermi GBM Final Localization
  50. GRB 221028A: Swift-XRT refined Analysis
  51. GRB 221028A: 1.3m DFOT Optical upper limit
  52. GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits
  53. GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits
  54. GRB 221028A: Correction to GCN 32893 - Fluence and flux are for 50-150 keV
  55. GRB 221028A: AKO Optical Upper Limit
  56. GRB 221028A, Swift-BAT refined analysis
  57. GRB 221027B: Swift-BAT refined analysis
  58. GRB 221029A: Swift/BAT-GUANO detection outside the coded FOV
  59. GRB 221029A: Detection by GRBAlpha
  60. GRB 221028A: CrAO/ZTSh optical upper limit
  61. GRB 221028A: COATLI Upper Limits
  62. Trigger 1132968: Swift trigger is the Crab
  63. GRB 221028A: HCT optical upper limit
  64. GRB 221028A: AGILE detection
  65. GRB 221027A: AGILE detection
  66. GRB 221028A: MITSuME Okayama optical upper limits
  67. GRB 221028B: MAXI/GSC detection
  68. GRB 221028A: LCOGT Optical Upper Limits
  69. GRB 221027B: COATLI Upper Limits
  70. Swift GRB 221028A: Global MASTER-Net observations report
  71. GRB 221028A: BOOTES-4/MET optical upper limit
  72. LIGO-Virgo-KAGRA and GEO600 statement on GRB 221009A
  73. GRB 221028A: GIT optical upper limit
  74. GRB 221027B: Swift/UVOT Upper Limits
  75. GRB 221028A: Swift detection of a burst
  76. GRB 221027B: FRAM-ORM and Ondrejov SBT optical limits
  77. Konus-Wind detection of GRB 221017A
  78. Swift GRB 221027B: Global MASTER-Net observations report
  79. GRB 221027B: Swift-XRT refined Analysis
  80. GRB 221027B: BOOTES-1 optical upper limit
  81. GRB 221027B: Enhanced Swift-XRT position
  82. GRB 221027B: Swift detection of a burst
  83. GRB 221027A: Fermi GBM detection
  84. IPN triangulation of GRB 221025A (short)
  85. Konus-Wind detection of GRB 221022B
  86. GRB 221024A: Mondy optical observations
  87. GRB 221027A: Fermi-LAT detection
  88. GRB 221027A: Fermi GBM Final Real-time Localization
  89. GRB 221009A: Further Gemini-South Infrared Observations
  90. GRB 221024A: GRANDMA observations
  91. Fermi Gamma-ray Burst Monitor trigger 688431261/221025954 is not a GRB
  92. IPN triangulation of GRB 221022C (short)
  93. GRB 221023A: AGILE/GRID analysis
  94. SGR 1935+2154: AstroSat CZTI Detections
  95. GRB 221024A: Swift-BAT refined analysis
  96. GRB 221025A: AstroSat CZTI detection
  97. GRB 221009A: SARA-RM 1m Optical Afterglow Detection
  98. GRB 221025A: Fermi GBM Observation
  99. GRB 221009A: spectroscopic confirmation of SN in LBT spectra
  100. Konus-Wind detection of GRB 221023A

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