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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"

26151 results found.

  1. GRB 251111A: LCO optical observation
  2. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  3. GRB 251111A: SVOM detection of a soft burst
  4. GRB 251103B: Swift-BAT refined analysis
  5. GRB 251106A: Swift/UVOT Upper Limits
  6. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  7. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  8. GRB 251108A: Fermi GBM Final Localization Correction
  9. Fermi trigger No 784329591: Global MASTER-Net observations report
  10. Fermi trigger No 784279167: Global MASTER-Net observations report
  11. SVOM GRB251108.54: Global MASTER-Net observations report
  12. GRB 251102B: SVOM/GRM observation
  13. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  14. The EP-WXT trigger 01709248051 is likely a flaring star
  15. SVOM GRB251106.83: Global MASTER-Net observations report
  16. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  17. GRB 251106B: SVOM/GRM observation of a short burst
  18. GRB 251106A: Kilonova-Catcher optical upper limit
  19. Fermi GBM Sub-Threshold Detection of GRB 251106A
  20. GRB 251106A: Swift/BAT arcminute localization of a burst
  21. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  22. GRB 251106A: MASTER optical observations
  23. GRB 251106A: SVOM detection of a burst
  24. Fermi trigger No 784034269: Global MASTER-Net observations report
  25. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  26. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  27. GRB 251105A: Fermi GBM Observation
  28. GRB 251105C: Fermi GBM Final Localization Correction
  29. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  30. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  31. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  33. Fermi GBM Sub-Threshold Detection of GRB 251105B
  34. GRB 251103B: Swift/UVOT Upper Limits
  35. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  36. Fermi GRB 251105A: Global MASTER-Net observations report
  37. GRB 251105A: Fermi GBM Final Real-time Localization
  38. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  39. GRB 251103B: Fermi GBM observation
  40. GRB 251104A: SVOM detection of a burst
  41. EP251102a: FTW optical and NIR observations
  42. GRB 251103A: WFST optical observations
  43. EP251102a: update of EP-FXT follow-up observation
  44. GRB 251103A: Xinglong 2.16m optical detection
  45. GRB 251103B: Nanshan/HMT optical upper limit
  46. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  47. GRB 251103B: MITSuME Akeno optical upper limits
  48. GRB 251103B: Swift-XRT refined Analysis
  49. Fermi GRB 251103A: Global MASTER-Net observations report
  50. EP251102a: NIR observations with WINTER
  51. GRB 251103A: J-band detection with WINTER
  52. Swift GRB 251103B: Global MASTER-Net observations report
  53. GRB 251103B: GROWTH-India Telescope optical upper limits
  54. GRB 251103A: Kilonova-Catcher optical afterglow detection
  55. GRB 251103B: Swift detection of a burst
  56. GRB 251103B: Fermi GBM Final Real-time Localization
  57. GRB 251103A: Swift/UVOT Detection
  58. GRB 251103A: Fermi GBM Observation
  59. GRB 251103A: SVOM/GRM observation
  60. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  61. EP251102a: Einstein Probe detection of a fast X-ray transient
  62. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  63. GRB 251103A: LCO optical observation
  64. EP251102.890: COLIBRÍ optical counterpart candidate
  65. GRB 251103A: GOTO optical afterglow detection
  66. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  67. GRB 251103A: BOOTES-2/TELMA optical afterglow
  68. GRB 251103A: LCO optical afterglow detection
  69. GRB 251103A: Fermi GBM Final Localization
  70. GRB 251103A: NOT optical afterglow candidate
  71. GRB 251103A: SVOM detection of a bright burst
  72. GRB 251102B: Fermi GBM Final Real-time Localization
  73. Fermi GRB 251102A: Global MASTER-Net observations report
  74. GRB 251102A: Fermi GBM Final Real-time Localization
  75. GRB 251031A: Fermi GBM Observation
  76. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  77. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  78. GRB 251031A: Fermi GBM Final Real-time Localization
  79. GRB 251025C: SVOM/GRM observation
  80. GRB 251028A: GECAM-B detection
  81. GRB 251028A: SVOM/GRM observation
  82. GRB 251028A: Fermi GBM Observation
  83. GRB 251026B: LBT near-infrared observations
  84. GRB 250926A: VZLUSAT-2 detection
  85. GRB 251026B: Fermi GBM Observation
  86. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  87. GRB 251026A/EP251026a: EP-FXT follow-up observation
  88. The EP-WXT trigger 01709247588 is likely a flaring star
  89. GRB 251028B: Fermi/GBM observation
  90. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  92. Fermi GRB 251028B: Global MASTER-Net observations report
  93. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  94. GRB 251028B: Fermi GBM Final Localization Correction
  95. GRB251026B: PRIME H-band upper limit
  96. GRB251025B: 3.6m DOT Optical Observations
  97. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  98. GRB 251028A: Fermi GBM Final Real-time Localization
  99. The EP-WXT trigger 01709247525 is not a real source
  100. SVOM trigger sb25102702/GRB 251027A is not a GRB

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