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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"

27039 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  2. The EP-WXT trigger 01709248051 is likely a flaring star
  3. SVOM GRB251106.83: Global MASTER-Net observations report
  4. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  5. GRB 251106B: SVOM/GRM observation of a short burst
  6. GRB 251106A: Kilonova-Catcher optical upper limit
  7. Fermi GBM Sub-Threshold Detection of GRB 251106A
  8. GRB 251106A: Swift/BAT arcminute localization of a burst
  9. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  10. GRB 251106A: MASTER optical observations
  11. GRB 251106A: SVOM detection of a burst
  12. Fermi trigger No 784034269: Global MASTER-Net observations report
  13. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  14. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  15. GRB 251105A: Fermi GBM Observation
  16. GRB 251105C: Fermi GBM Final Localization Correction
  17. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  18. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  21. Fermi GBM Sub-Threshold Detection of GRB 251105B
  22. GRB 251103B: Swift/UVOT Upper Limits
  23. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  24. Fermi GRB 251105A: Global MASTER-Net observations report
  25. GRB 251105A: Fermi GBM Final Real-time Localization
  26. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  27. GRB 251103B: Fermi GBM observation
  28. GRB 251104A: SVOM detection of a burst
  29. EP251102a: FTW optical and NIR observations
  30. GRB 251103A: WFST optical observations
  31. EP251102a: update of EP-FXT follow-up observation
  32. GRB 251103A: Xinglong 2.16m optical detection
  33. GRB 251103B: Nanshan/HMT optical upper limit
  34. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  35. GRB 251103B: MITSuME Akeno optical upper limits
  36. GRB 251103B: Swift-XRT refined Analysis
  37. Fermi GRB 251103A: Global MASTER-Net observations report
  38. EP251102a: NIR observations with WINTER
  39. GRB 251103A: J-band detection with WINTER
  40. Swift GRB 251103B: Global MASTER-Net observations report
  41. GRB 251103B: GROWTH-India Telescope optical upper limits
  42. GRB 251103A: Kilonova-Catcher optical afterglow detection
  43. GRB 251103B: Swift detection of a burst
  44. GRB 251103B: Fermi GBM Final Real-time Localization
  45. GRB 251103A: Swift/UVOT Detection
  46. GRB 251103A: Fermi GBM Observation
  47. GRB 251103A: SVOM/GRM observation
  48. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. EP251102a: Einstein Probe detection of a fast X-ray transient
  50. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  51. GRB 251103A: LCO optical observation
  52. EP251102.890: COLIBRÍ optical counterpart candidate
  53. GRB 251103A: GOTO optical afterglow detection
  54. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  55. GRB 251103A: BOOTES-2/TELMA optical afterglow
  56. GRB 251103A: LCO optical afterglow detection
  57. GRB 251103A: Fermi GBM Final Localization
  58. GRB 251103A: NOT optical afterglow candidate
  59. GRB 251103A: SVOM detection of a bright burst
  60. GRB 251102B: Fermi GBM Final Real-time Localization
  61. Fermi GRB 251102A: Global MASTER-Net observations report
  62. GRB 251102A: Fermi GBM Final Real-time Localization
  63. GRB 251031A: Fermi GBM Observation
  64. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  65. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  66. GRB 251031A: Fermi GBM Final Real-time Localization
  67. GRB 251025C: SVOM/GRM observation
  68. GRB 251028A: GECAM-B detection
  69. GRB 251028A: SVOM/GRM observation
  70. GRB 251028A: Fermi GBM Observation
  71. GRB 251026B: LBT near-infrared observations
  72. GRB 250926A: VZLUSAT-2 detection
  73. GRB 251026B: Fermi GBM Observation
  74. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  75. GRB 251026A/EP251026a: EP-FXT follow-up observation
  76. The EP-WXT trigger 01709247588 is likely a flaring star
  77. GRB 251028B: Fermi/GBM observation
  78. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  79. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  80. Fermi GRB 251028B: Global MASTER-Net observations report
  81. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  82. GRB 251028B: Fermi GBM Final Localization Correction
  83. GRB251026B: PRIME H-band upper limit
  84. GRB251025B: 3.6m DOT Optical Observations
  85. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  86. GRB 251028A: Fermi GBM Final Real-time Localization
  87. The EP-WXT trigger 01709247525 is not a real source
  88. SVOM trigger sb25102702/GRB 251027A is not a GRB
  89. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  90. GRB 251027A: Swift-XRT observations
  91. EP251027.145: COLIBRÍ optical upper limits
  92. GRB 251022A: SVOM/GRM observation
  93. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  94. GRB 251027A: LCO optical upper limit
  95. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 251025B: Kilonova-Catcher optical afterglow detection
  97. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  98. GRB 251027A: SVOM detection of a faint burst
  99. GRB 251026B: Tentative GOTO optical counterpart candidate
  100. GRB 251025C: CALET Gamma-Ray Burst Monitor detection

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