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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"

34116 results found.

  1. GRB 221120A: Liverpool Telescope Upper Limits
  2. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  3. GRB 221120A: Fermi GBM observation
  4. GRB 221120A: Swift-XRT refined Analysis
  5. GRB 221120A: Enhanced Swift-XRT position
  6. GRB 221121A: Fermi GBM Final Real-time Localization
  7. GRB 221120A is a short burst
  8. GRB 221120A: Swift/UVOT Upper Limits
  9. GRB 221120A: LDT Optical Afterglow Candidate
  10. GRB 221120A: GIT upper limits on optical afterglow
  11. GRB 221120A: Swift detection of a likely short burst
  12. GRB 221119A: Fermi GBM detection
  13. GRB 221119A: Detection by GRBAlpha
  14. GRB 221119A: Fermi-LAT detection
  15. GRB 221119A: Fermi GBM Final Real-time Localization
  16. GRB 221009A: Japanese VLBI Network observation
  17. GRB 221115B: CALET Gamma-Ray Burst Monitor detection
  18. GRB 221114A: CALET Gamma-Ray Burst Monitor detection
  19. GRB 221118A: Fermi GBM Final Real-time Localization
  20. GRB 221115B: LCOGT Optical Upper Limits
  21. Correction to GCN 32646 (GRB 221009A (Swift J1913.1+1946): MeerLICHT observations)
  22. GRB 221115B : MeerLICHT upper limits
  23. GRB 221115A: Fermi GBM detection
  24. GRB 221115B: Swift/BAT-GUANO arcminute localization
  25. GRB 221115A: Swift/BAT-GUANO detection
  26. GRB 221110A: GRANDMA observations
  27. GRB 221112A: Detection by GRBAlpha
  28. GRB 221112A: Fermi GBM Final Real-time Localization
  29. GRB 221110A: COATLI Second-Epoch Upper Limits
  30. GRB 221009A: GRANDMA/Kilonova-Catcher observations
  31. GRB 221110A: GMG upper limit
  32. GRB 221110A: Swift/UVOT Detection and Corrected UVOT Position
  33. GRB 221110A: Swift-BAT refined analysis
  34. GRB 221110A: Swift-XRT refined Analysis
  35. GRB 221110A: Enhanced Swift-XRT position
  36. GRB 221110A: VLT/X-shooter redshift
  37. GRB 221110A: COATLI Afterglow detection
  38. GRB 221110A: LCOGT Optical Afterglow Detection
  39. GRB 221110A: Swift detection of a burst with an optical counterpart
  40. GRB 221009A: Hubble Space Telescope observations
  41. GRB 221104A: Fermi GBM Final Localization
  42. GRB 221108A: Fermi GBM Final Localization
  43. GRB 221107A: Fermi GBM Observation
  44. GRB 221107A: Detection by GRBAlpha
  45. GRB 221009A: Extended Bad Time Intervals for Fermi LAT data
  46. GRB 221107A: Swift/BAT-GUANO detection outside the coded FOV
  47. GRB 221107A: Fermi GBM Final Localization
  48. Correction to GCN 32852 (GRB 221009A: SARA-RM 1m Optical Afterglow Detection)
  49. GRB 221029A: CALET Gamma-Ray Burst Monitor detection
  50. High-precision position of the compact radio counterpart to GRB221009A
  51. GRB 221028A: GRANDMA observations
  52. GRB 221027B: GRANDMA observations
  53. GRB 221028A: Detection by VZLUSAT-2
  54. GRB 221029A: Fermi GBM observation
  55. GRB 221027C: AstroSat CZTI detection
  56. Konus-Wind detection of GRB 221022C
  57. GRB 221029A: Fermi GBM Final Localization
  58. GRB 221028A: Swift-XRT refined Analysis
  59. GRB 221028A: 1.3m DFOT Optical upper limit
  60. GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits
  61. GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits
  62. GRB 221028A: Correction to GCN 32893 - Fluence and flux are for 50-150 keV
  63. GRB 221028A: AKO Optical Upper Limit
  64. GRB 221028A, Swift-BAT refined analysis
  65. GRB 221027B: Swift-BAT refined analysis
  66. GRB 221029A: Swift/BAT-GUANO detection outside the coded FOV
  67. GRB 221029A: Detection by GRBAlpha
  68. GRB 221028A: CrAO/ZTSh optical upper limit
  69. GRB 221028A: COATLI Upper Limits
  70. GRB 221028A: HCT optical upper limit
  71. GRB 221028A: AGILE detection
  72. GRB 221027A: AGILE detection
  73. GRB 221028A: MITSuME Okayama optical upper limits
  74. GRB 221028B: MAXI/GSC detection
  75. GRB 221028A: LCOGT Optical Upper Limits
  76. GRB 221027B: COATLI Upper Limits
  77. Swift GRB 221028A: Global MASTER-Net observations report
  78. GRB 221028A: BOOTES-4/MET optical upper limit
  79. LIGO-Virgo-KAGRA and GEO600 statement on GRB 221009A
  80. GRB 221028A: GIT optical upper limit
  81. GRB 221027B: Swift/UVOT Upper Limits
  82. GRB 221028A: Swift detection of a burst
  83. GRB 221027B: FRAM-ORM and Ondrejov SBT optical limits
  84. Konus-Wind detection of GRB 221017A
  85. Swift GRB 221027B: Global MASTER-Net observations report
  86. GRB 221027B: Swift-XRT refined Analysis
  87. GRB 221027B: BOOTES-1 optical upper limit
  88. GRB 221027B: Enhanced Swift-XRT position
  89. GRB 221027B: Swift detection of a burst
  90. GRB 221027A: Fermi GBM detection
  91. IPN triangulation of GRB 221025A (short)
  92. Konus-Wind detection of GRB 221022B
  93. GRB 221024A: Mondy optical observations
  94. GRB 221027A: Fermi-LAT detection
  95. GRB 221027A: Fermi GBM Final Real-time Localization
  96. GRB 221009A: Further Gemini-South Infrared Observations
  97. GRB 221024A: GRANDMA observations
  98. Fermi Gamma-ray Burst Monitor trigger 688431261/221025954 is not a GRB
  99. IPN triangulation of GRB 221022C (short)
  100. GRB 221023A: AGILE/GRID analysis

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