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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. Swift GRB240221.92: Global MASTER-Net observations report
  2. GRB 240218A: MeerLICHT upper limits
  3. GRB 240216A: Glowbug gamma-ray detection
  4. GRB 240215B: Fermi GBM Observation
  5. GRB 240218A: LBT H-band detection
  6. GRB 240218A: Swift-BAT refined analysis
  7. Fermi GRB 240220A: Global MASTER-Net observations report
  8. GRB 240220A: Fermi GBM Final Real-time Localization
  9. Konus-Wind detection of GRB 240218A
  10. GRB 240218A: Swift-XRT refined Analysis
  11. GRB 240218A: VLT/X-shooter redshift of z = 6.782
  12. GRB 240218A: Fermi GBM Detection
  13. GRB 240215A: Fermi GBM Observation
  14. GRB 240216A: GRBAlpha detection
  15. GRB 240215B: GRBAlpha detection
  16. IPN triangulation of GRB 240209A
  17. Fermi trigger No 729914426: Global MASTER-Net observations report
  18. GRB 240218A: VLT/FORS2 z-band detection
  19. GRB 240218A: Enhanced Swift-XRT position
  20. GRB 240218A: REM detection of a NIR afterglow candidate
  21. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  22. GRB 240213A: GRBAlpha detection
  23. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  24. GRB240218A: VLT/X-shooter upper limits
  25. GRB 240218A: Swift detection of a burst
  26. Swift GRB240218.08: Global MASTER-Net observations report
  27. GRB 240215C: Fermi GBM Final Real-time Localization
  28. GRB 240215B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  29. Fermi GRB 240216A: Global MASTER-Net observations report
  30. Swift Triggers 12156887-1215690 are not astrophysical events.
  31. GRB 240216A: Fermi GBM Final Real-time Localization
  32. Fermi trigger No 729719508: Global MASTER-Net observations report
  33. GRB 240215A: Tiled Swift observations
  34. GRB 240215A: Swift/BAT-GUANO localization of a burst
  35. Fermi trigger No 729703985: Global MASTER-Net observations report
  36. Fermi trigger No 729650855: Global MASTER-Net observations report
  37. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  38. GRB 240209A: Fermi GBM observation
  39. GRB 240213A: Glowbug gamma-ray detection
  40. The AGILE satellite ceased operations and re-entered today into the atmosphere
  41. The AGILE satellite ceased operations and re-entered today into the atmosphere
  42. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  43. GRB 240209A: Wendelstein Optical Observations
  44. GRB 240128A: Further Swift-XRT observations
  45. GRB 240214A: Tiled Swift observations
  46. GRB 240214A/1H 0451-560: MAXI/GSC detection
  47. GRB 240213A: BALROG localization (Fermi Trigger / GRB 240213841)
  48. Fermi GRB 240213A: Global MASTER-Net observations report
  49. GRB 240213A: Fermi GBM Final Real-time Localization
  50. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  51. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  52. GRB 240209A: GOTO optical counterpart candidate
  53. Konus-Wind detection of GRB 240204A
  54. Konus-Wind detection of GRB 240205A (short)
  55. GRB 240209A: Fermi GBM Final Localization
  56. Fermi trigger No 729152364: Global MASTER-Net observations report
  57. IPN triangulation of GRB 240205A (short)
  58. Fermi-LAT gamma-ray observations of IceCube-240204A
  59. GRB 240205B: PRIME near infrared detection
  60. GRB 240205A (short): Glowbug gamma-ray detection
  61. Swift Trigger 1213872 is not an astrophysical event
  62. GRB240204A: Swift/UVOT Upper Limits
  63. GRB 240205B: AstroSat CZTI detection
  64. Fermi trigger No 729012023: Global MASTER-Net observations report
  65. GRB 240205B: Swift-BAT refined analysis
  66. Konus-Wind detection of GRB 240205B (long / very soft)
  67. GRB 240207A: Fermi GBM Final Real-time Localization
  68. Konus-Wind detection of GRB 240125A
  69. GRB 240205B: VLT/X-shooter redshift
  70. GRB 240205B: CALET Gamma-Ray Burst Monitor detection
  71. GRB 240205B: BOOTES-6 optical afterglow follow-up
  72. GRB 240205B: ATCA detection of radio counterpart
  73. GRB 240205B: REM detection of the optical/NIR afterglow
  74. GRB 240205B: Fermi GBM Observation
  75. GRB 240204A: AstroSat CZTI detection
  76. GRB 240204A: Mondy optical afterglow observations
  77. GRB 240204A : OHP/T193/T120 optical afterglow fading detection
  78. GRB 240205B: GECAM detection of a long burst
  79. GRB 240204A: Swift-BAT refined analysis
  80. GRB 240205B: Skynet Optical Afterglow Observations
  81. GRB 240205B: BOOTES-7 optical afterglow follow-up
  82. Fermi trigger No 728749569: Global MASTER-Net observations report
  83. GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
  84. GRB 240205B: Swift detection of a burst
  85. GRB 240205B: Fermi GBM Final Real-time Localization
  86. Swift GRB240205.93: Global MASTER-Net observations report
  87. GRB 240204A: Fermi GBM Observation
  88. GRB 240205A: Fermi GBM Final Real-time Localization
  89. GRB 240204a: Liverpool Telescope optical afterglow detection
  90. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  91. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  92. Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
  93. Fermi trigger No 728796365: Global MASTER-Net observations report
  94. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  95. GRB 240204A: Montarrenti Observatory optical observations
  96. GRB 240204A: Enhanced Swift-XRT position
  97. GRB 240204A: Mondy optical afterglow candidate
  98. Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  99. Fermi GRB 240204A: Global MASTER-Net observations report
  100. Fermi trigger No 728706420: Global MASTER-Net observations report

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