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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').
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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"

11527 results found.

  1. GRB 241209C: Fermi GBM Observation
  2. Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
  3. GRB 241209D: AstroSat CZTI detection
  4. GRB 241209A: EP-FXT follow-up observations
  5. Fermi trigger No 755485387: Global MASTER-Net observations report
  6. GRB 241207B: Fermi GBM Observation
  7. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  8. GRB 241209D: Fermi GBM Observation
  9. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  10. GRB 241209D: COLIBRÍ detection of the afterglow
  11. GRB 241209A: COLIBRÍ Optical Upper Limit
  12. Fermi GRB 241209D: Global MASTER-Net observations report
  13. GRB 241209A: Fermi GBM Observation
  14. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  15. GRB 241209A: GRANDMA/TAROT upper limit
  16. Fermi GRB 241209C: Global MASTER-Net observations report
  17. Fermi GRB 241209E: Global MASTER-Net observations report
  18. GRB 241209E: Fermi GBM Final Real-time Localization
  19. GRB 241209A: REM optical/NIR observations
  20. GRB 241209C: AstroSat CZTI detection
  21. GRB 241209D: Fermi GBM Final Real-time Localization
  22. GRB 241209A: VLT/X-shooter spectroscopy
  23. GRB 241209A: VLT optical observations
  24. Fermi GRB 241209A: Global MASTER-Net observations report
  25. GRB 241209C: Fermi GBM Final Real-time Localization
  26. GRB 241209A: GOTO optical upper limits
  27. GRB 241209A: Swift detection of a short burst
  28. GRB 241209A: Fermi GBM Final Real-time Localization
  29. Fermi GRB 241207B: Global MASTER-Net observations report
  30. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  31. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  32. GRB 241201A: AstroSat CZTI detection
  33. GRB 241206A: DDOTI Upper Limit on the Afterglow
  34. Fermi trigger No 755225799: Global MASTER-Net observations report
  35. GRB 241207B: Fermi GBM Final Real-time Localization
  36. Fermi trigger No 755277791: Global MASTER-Net observations report
  37. Fermi GRB 241207A: Global MASTER-Net observations report
  38. GRB 241206A: Fermi GBM observation
  39. GRB 241207A: Fermi GBM Final Real-time Localization
  40. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  41. Fermi GRB 241206A: Global MASTER-Net observations report
  42. GRB 241206A: Fermi GBM Final Real-time Localization
  43. GRB 241204A: COLIBRÍ Optical Upper Limit
  44. GRB 241204A: DDOTI Upper Limits on the Afterglow
  45. GRB 241204A: Fermi GBM Observation
  46. Fermi GRB 241204A: Global MASTER-Net observations report
  47. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 241201A: GRBAlpha detection
  49. GRB 241204A: Fermi-LAT detection
  50. EP241202b: Upper limits from Fermi-GBM Observations
  51. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  52. Konus-Wind detection of GRB 241130A
  53. IPN triangulation of GRB 241130A
  54. GRB 241130A: EIRSAT-1 GMOD Detection
  55. GRB 241130A: Fermi GBM Detection
  56. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  57. GRB241201B: Fermi GBM Final Localization
  58. GRB241201B: Fermi GBM Final Localization
  59. Fermi GRB 241201A: Global MASTER-Net observations report
  60. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  61. GRB 241130A: Fermi GBM Final Real-time Localization
  62. GRB 241130A: Fermi GBM Final Real-time Localization
  63. GRB 241201A: Fermi GBM Final Real-time Localization
  64. Fermi trigger No 754701230: Global MASTER-Net observations report
  65. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  66. Fermi-LAT gamma-ray observations of IceCube-241127A
  67. GRB 241129A: Fermi GBM Final Real-time Localization
  68. Fermi trigger No 754492985: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  70. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 241026A: radio detection with the VLA
  72. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  73. GRB 241120A: GRBAlpha detection
  74. Konus-Wind detection of GRB 241117A
  75. GRB 241105A: ATCA radio detection
  76. IPN triangulation of GRB 241117A
  77. GRB 241026A: VIRT Optical Upper Limit
  78. GRB 241025A: VIRT Optical Upper Limit
  79. Konus-Wind detection of GRB 241120A
  80. GRB241120A: OHP/T193 optical observations
  81. GRB 241120A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 241120A: Mondy and AbAO optical observations
  83. GRB 241120A: Fermi GBM Observation
  84. GRB241120A: a long GRB detected by INTEGRAL
  85. GRB 241120A: Fermi GBM Final Real-time Localization
  86. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 241119A: Fermi GBM Final Real-time Localization
  88. GRB 241115a: PRIME near-infrared upper limits
  89. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  90. GRB 241115B: Fermi GBM Observation
  91. Fermi GRB 241118A: Global MASTER-Net observations report
  92. GRB 241118A: Fermi GBM Final Real-time Localization
  93. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  94. GRB 241117A: Fermi GBM Detection
  95. Fermi GRB 241117B: Global MASTER-Net observations report
  96. GRB 241117B: Fermi GBM Final Real-time Localization
  97. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  98. Fermi GRB 241117A: Global MASTER-Net observations report
  99. GRB 241117A: Fermi GBM Final Real-time Localization
  100. GRB 241115C: Fermi GBM Observation

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