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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"

2722 results found.

  1. GRB 250129A: REM optical/NIR afterglow detection
  2. GRB 250129A: GOTO optical observations show brightening afterglow
  3. Fermi GRB 250128B: Global MASTER-Net observations report
  4. GRB 250129A: Swift detection of a burst with an optical counterpart
  5. GRB 250117A: Fermi GBM Observation
  6. Fermi GRB 250127B: Global MASTER-Net observations report
  7. IPN triangulation of GRB 250119C
  8. GECAM-A detection of a bright burst from SGR 1E1841-045
  9. EP250125a: Optical upper limit with Kinder observations
  10. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  11. IPN triangulation of a bright burst from SGR 1E1841-045
  12. GRB 250119B: Fermi GBM Observation
  13. GRB 250118A: Fermi GBM Final Real-time Localization
  14. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  15. Integral GRB250114.55: Global MASTER-Net observations report
  16. EP250108a / AT 2025kg: SAO RAS optical observations
  17. GRB 250101B: Fermi GBM Observation
  18. Fermi GRB 250107B: Global MASTER-Net observations report
  19. GRB 250103B: REM optical/NIR upper limits
  20. GRB 250101A: REM optical/NIR counterpart detection
  21. GRB 250106A: Swift-XRT observations
  22. GRB 250101A: Swift-BAT refined analysis
  23. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  24. GRB 241229B: SAO RAS optical upper limit
  25. GRB 241229A: SAO RAS optical observations
  26. GRB 240606B: 7DT Optical upper limits
  27. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  28. Fermi GRB 241228B: Global MASTER-Net observations report
  29. GRB 241228B: GOTO possible optical counterpart candidate
  30. GRB 241212A: VZLUSAT-2 detection
  31. GRB 241223A: Fermi GBM Detection
  32. Fermi trigger No 756678579: Global MASTER-Net observations report
  33. IceCube Alert 241224.30: Global MASTER-Net observations report
  34. GRB241113A: 7DT Optical upper limits
  35. GRB 241105A: JWST photometric observations of the host galaxy
  36. GRB 241223A: Fermi GBM Final Real-time Localization
  37. EP241217a : Leavitt Observatory optical upper limit
  38. EP241119a: 7DT Optical upper limits
  39. GRB 241213B: MAXI/GSC detection
  40. GRB 241209A: Chandra X-ray Detection
  41. Fermi GRB 241209E: Global MASTER-Net observations report
  42. Fermi GRB 241209A: Global MASTER-Net observations report
  43. GRB 241207C: MASTER optical observations
  44. Fermi trigger No 755225799: Global MASTER-Net observations report
  45. GRB 241207C: MAXI/GSC detection
  46. Fermi GRB 241207A: Global MASTER-Net observations report
  47. EP241206a: EP detection of a fast X-ray transient
  48. Fermi GRB 241204A: Global MASTER-Net observations report
  49. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  50. GRB 241130A: Fermi GBM Detection
  51. Fermi GRB 241201A: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  53. GRB 241128A: AbAO optical upper limit
  54. EP241126a: WFST Observations
  55. Swift GRB241127.91: Global MASTER-Net observations report
  56. Fermi GRB 241118A: Global MASTER-Net observations report
  57. GRB 241117A: Fermi GBM Detection
  58. EP241113a: Swift XRT weak detection
  59. EP241115a: EP detection of a fast X-ray transient
  60. EP 241113a: LBT possible optical counterpart
  61. GRB 241113B: KAIT Optical Afterglow Candidate
  62. EP241113a: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  64. Fermi trigger No 753166198: Global MASTER-Net observations report
  65. EP241107a: EP-FXT follow-up observations
  66. Fermi trigger No 752990530: Global MASTER-Net observations report
  67. Fermi trigger No 752878030: Global MASTER-Net observations report
  68. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  69. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  70. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  71. Fermi GRB 241105A: Global MASTER-Net observations report
  72. Fermi GRB 241104A: Global MASTER-Net observations report
  73. EP241101a: Optical upper limits with Kinder observations
  74. S241102cy: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  76. GRB 241026A: SAO RAS optical observations
  77. Fermi trigger No 752006065: Global MASTER-Net observations report
  78. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  79. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  80. GRB 241030A: Fermi GBM Final Real-time Localization
  81. GRB 241029A: Mephisto observations
  82. GRB 241026A: BTA and Zeiss-1000 optical observations
  83. EP241021a: further SAO RAS optical observations
  84. EP EP241026b: Global MASTER-Net observations report
  85. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  86. GRB 241025A: Fermi GBM Observation
  87. IPN triangulation of GRB 241022A (short/hard)
  88. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  89. GRB 241018A: EP-FXT afterglow detection
  90. GRB 240727A: VIRT Optical Upper Limit
  91. Fermi trigger No 750788395: Global MASTER-Net observations report
  92. Fermi GRB 241016A: Global MASTER-Net observations report
  93. Fermi trigger No 750211959: Global MASTER-Net observations report
  94. GRB 241010A: LCO optical observations
  95. Fermi GRB 241008A: Global MASTER-Net observations report
  96. IceCube-241006A: No candidates from the Zwicky Transient Facility
  97. IceCube Alert 241006.94: Global MASTER-Net observations report
  98. GRB 241006A: Swift detection of a burst
  99. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  100. Fermi trigger No 749693019: Global MASTER-Net observations report

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