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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"

11509 results found.

  1. GRB 250207a: ATCA Radio Upper Limits
  2. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  3. GRB 250119B: VZLUSAT-2 detection
  4. GRB 250223C: Fermi GBM Final Real-time Localization
  5. GRB 250202B: VZLUSAT-2 detection
  6. GRB 250210A: VZLUSAT-2 detection
  7. GRB 250206A: VZLUSAT-2 detection
  8. GRB 250223B: Fermi GBM Final Localization
  9. Fermi GRB 250223A: Global MASTER-Net observations report
  10. Fermi trigger No 762020305: Global MASTER-Net observations report
  11. GRB 250223A: Fermi GBM Final Real-time Localization
  12. Fermi trigger No 761805304: Global MASTER-Net observations report
  13. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  14. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  15. GRB 250220B: Fermi GBM Final Real-time Localization
  16. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  17. GRB 250220A: Fermi GBM Final Real-time Localization
  18. Konus-Wind detection of GRB 250217C (short)
  19. Konus-Wind detection of GRB 250215A / EP250215a
  20. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  21. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  22. GRB 250217C: SVOM/GRM observation
  23. GRB 250217C: Fermi GBM Observation
  24. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  25. IPN triangulation of GRB 250217C (short)
  26. GRB 250216A: AstroSat CZTI detection
  27. GRB 250217C: AstroSat CZTI detection of a short burst
  28. Fermi GRB 250217C: Global MASTER-Net observations report
  29. GRB 250217C: Fermi GBM Final Real-time Localization
  30. Fermi GRB 250217A: Global MASTER-Net observations report
  31. GRANDMA/OPD observations of GRB250215A
  32. GRB 250217B: Fermi GBM Final Real-time Localization
  33. GRB 250217A: Fermi GBM Final Real-time Localization
  34. Fermi GRB 250216A: Global MASTER-Net observations report
  35. GRB 250215A / EP250215a: LCO detection of the afterglow
  36. GRB 250216A: Fermi GBM Final Real-time Localization
  37. GRB 250215A: Swift/UVOT Upper Limits
  38. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  39. EP250215a / GRB 250215A : GTC redshift z = 4.61
  40. GRB 250215A: Fermi GBM Observation
  41. EP250215a / GRB 250215A : NOT optical observations
  42. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  43. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  44. GRB 250215A: Swift-XRT refined Analysis
  45. GRB 250215A: SVOM/GRM observation
  46. EP250215a / GRB 250215A: AstroSat CZTI detection
  47. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  48. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  49. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  50. Fermi GRB 250215A: Global MASTER-Net observations report
  51. GRB 250215A: Fermi GBM Final Real-time Localization
  52. Fermi trigger No 761206993: Global MASTER-Net observations report
  53. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  54. Fermi GRB 250214A: Global MASTER-Net observations report
  55. GRB 250214A: Fermi GBM Final Real-time Localization
  56. GRB 250210A: GRBAlpha detection
  57. Fermi GRB 250212A: Global MASTER-Net observations report
  58. Fermi trigger No 760945500: Global MASTER-Net observations report
  59. GRB 250212A: Fermi GBM Final Real-time Localization
  60. GRB 250207A: Fermi GBM Observation
  61. GRB 250206A: Fermi GBM Observation
  62. GRB 250205A / EP250205A: radio detection with the VLA
  63. Konus-Wind detection of GRB 250207A
  64. Konus-Wind detection of GRB 250206A
  65. GRB 250210A: SVOM/GRM observation of a long burst
  66. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  67. GRB 250207A: Skynet optical afterglow observations
  68. EP250207A: Upper limits from Fermi-GBM Observations
  69. GRB 250210A: INTEGRAL SPI-ACS detection
  70. GRB 250210A: AstroSat CZTI detection
  71. Fermi GRB 250210A: Global MASTER-Net observations report
  72. GRB 250210A: Fermi GBM Final Real-time Localization
  73. GRB 250204B: GRBAlpha detection
  74. GRB 250204A: GRBAlpha detection
  75. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  76. GRB 250206A: Swift-XRT observations
  77. GRB 250206A: Tiled Swift observations
  78. GRB 250206A: EIRSAT-1 GMOD Detection
  79. GRB 250206A: Fermi-LAT detection
  80. GRB 250208A: Fermi GBM Final Real-time Localization
  81. GRB 250207A: REM IR afterglow detection
  82. GRB 250207A: FRAM-Auger optical detection
  83. Konus-Wind detection of GRB 250204B
  84. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 250207A: REM optical afterglow detection
  86. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  87. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  88. GRB 250207A: Fermi GBM Final Real-time Localization
  89. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  90. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  91. GRB 250206A: Fermi GBM Final Real-time Localization
  92. GRB 250205A: Fermi GBM Observation
  93. GRB 250204B: SVOM/GRM observation of a likely short burst
  94. Konus-Wind detection of GRB 250201A
  95. IPN triangulation of GRB 250201A
  96. Konus-Wind detection of GRB 250202B
  97. EP 250108A: Upper limits from Fermi-GBM Observations
  98. IPN triangulation of GRB 250204B (short/hard)
  99. IPN triangulation of GRB 250202B
  100. GRB 250204B: AstroSat CZTI detection of a short burst

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