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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 221029A: Detection by GRBAlpha
  2. GRB 221028A: CrAO/ZTSh optical upper limit
  3. GRB 221028A: COATLI Upper Limits
  4. Trigger 1132968: Swift trigger is the Crab
  5. GRB 221028A: HCT optical upper limit
  6. GRB 221028A: AGILE detection
  7. GRB 221027A: AGILE detection
  8. GRB 221028A: MITSuME Okayama optical upper limits
  9. GRB 221028B: MAXI/GSC detection
  10. GRB 221028A: LCOGT Optical Upper Limits
  11. GRB 221027B: COATLI Upper Limits
  12. Swift GRB 221028A: Global MASTER-Net observations report
  13. GRB 221028A: BOOTES-4/MET optical upper limit
  14. LIGO-Virgo-KAGRA and GEO600 statement on GRB 221009A
  15. GRB 221028A: GIT optical upper limit
  16. GRB 221027B: Swift/UVOT Upper Limits
  17. GRB 221028A: Swift detection of a burst
  18. GRB 221027B: FRAM-ORM and Ondrejov SBT optical limits
  19. Konus-Wind detection of GRB 221017A
  20. Swift GRB 221027B: Global MASTER-Net observations report
  21. GRB 221027B: Swift-XRT refined Analysis
  22. GRB 221027B: BOOTES-1 optical upper limit
  23. GRB 221027B: Enhanced Swift-XRT position
  24. GRB 221027B: Swift detection of a burst
  25. GRB 221027A: Fermi GBM detection
  26. IPN triangulation of GRB 221025A (short)
  27. Konus-Wind detection of GRB 221022B
  28. GRB 221024A: Mondy optical observations
  29. GRB 221027A: Fermi-LAT detection
  30. GRB 221027A: Fermi GBM Final Real-time Localization
  31. GRB 221009A: Further Gemini-South Infrared Observations
  32. GRB 221024A: GRANDMA observations
  33. Fermi Gamma-ray Burst Monitor trigger 688431261/221025954 is not a GRB
  34. IPN triangulation of GRB 221022C (short)
  35. GRB 221023A: AGILE/GRID analysis
  36. SGR 1935+2154: AstroSat CZTI Detections
  37. GRB 221024A: Swift-BAT refined analysis
  38. GRB 221025A: AstroSat CZTI detection
  39. GRB 221009A: SARA-RM 1m Optical Afterglow Detection
  40. GRB 221025A: Fermi GBM Observation
  41. GRB 221009A: spectroscopic confirmation of SN in LBT spectra
  42. Konus-Wind detection of GRB 221023A
  43. GRB 221024A: Swift/UVOT UV upper limits
  44. GRB 221022A: Swift-XRT observations
  45. GRB 221024A: Swift-XRT refined Analysis
  46. GRB 221023A: Fermi GBM Observation
  47. GRB 221022B: Detection by GRBAlpha
  48. GRB 221025A: Fermi-LAT detection
  49. IPN triangulation of GRB 221022B (long)
  50. GRB 221024A: GIT confirmation of the optical afterglow
  51. LAT GRB221025.04: Global MASTER-Net observations report
  52. GRB 221024A: Enhanced Swift-XRT position
  53. GRB 221024A: D50 candidate afterglow
  54. GRB 221022B: AstroSat CZTI detection
  55. GRB 221022A: Fermi GBM detection
  56. GRB 221022A: Swift ToO observations
  57. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  58. GRB 221023A: Fermi-LAT detection
  59. GRB 221022B: Fermi GBM detection
  60. GRB 221021A: Fermi GBM observation
  61. GRB 221009A: Determination of the black holes mass and spin
  62. GRB 221024A: Swift detection of a burst
  63. GRB 221023A: Fermi GBM Final Localization
  64. GRB 221023A: AGILE detection of a burst
  65. GRB 221022A: Swift/BAT-GUANO detection
  66. GRB 221022B: Swift/BAT-GUANO detection outside the coded FOV
  67. GRB 221022B: AGILE detection
  68. GRB 221009A: James Webb Space Telescope Observations
  69. GRB 221022B: Fermi GBM Final Real-time Localization
  70. GRB 221009A: Analysis of the initial episode using data of GBM/Fermi and SPI-ACS/INTEGRAL
  71. GRB 221009A: optical observations, SN photometric evidence
  72. GRB 221021A: Swift/BAT-GUANO detection outside the coded FOV
  73. GRB 221022A: Fermi GBM Final Real-time Localization
  74. GRB 221020A: Detection by GRBAlpha
  75. SGR 1935+21542: VZLUSAT-2 and GRBAlpha joint detection
  76. GRB 221017A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 221021A: Fermi GBM Final Real-time Localization
  78. GRB 221009A: 1.3m DFOT Optical Observations
  79. Fermi GBM trigger 687320613 / 221013100 (GRB 221013B) is not a GRB
  80. GRB221009A: LBT optical imaging
  81. GRB 221009A: Peak luminosity of the supernova vs. synchrotron afterglow
  82. GRB 221017A: Swift-XRT observations
  83. GRB 221020A: Fermi GBM Final Real-time Localization
  84. Improved IPN localization for GRB 221009A (BepiColombo-MGNS light curve)
  85. GRB 221009A: TNG NIR detection
  86. GRB 221009A: BOAO NIR detections
  87. GRB 221009A X-ray light-curve and the indication of TeV light-curve
  88. AGILE detection of a burst from SGR J1935+2154 reported by VZLUSAT-2
  89. GRB 221009A: Spectroscopic detection of emerging SN features
  90. GRB 221009A: Continued LDT Afterglow Monitoring
  91. GRB 221013B: Swift/BAT-GUANO detection
  92. SGR 1935+2154: Bursting activity detected by VZLUSAT-2
  93. AGILE detection of the 2022 October 17 burst from SGR J1935+2154 reported by Konus-Wind
  94. GRB 221009A: GRANDMA observations
  95. SGR 1935+2154: Detection by GRBAlpha
  96. The probability of observing GRB 221009A at z = 0.151
  97. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 October 17
  98. GRB 221009A: Medicina Radio Telescope observations
  99. GRB 221017A: Swift ToO observations
  100. AGILE detection of short X-ray flaring activity contemporary to SGR J1935+2154 reported bursts

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