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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"

26130 results found.

  1. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  2. GRB 251023A: SVOM/GRM observation
  3. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  4. GRB 251025C: Fermi GBM Final Real-time Localization
  5. GRB 251025B: GROWTH-India Telescope optical observations
  6. GRB 251024A: Swift/UVOT Upper Limits
  7. GRB 251024A: Swift-BAT refined analysis
  8. IceCube Alert 251025.57: Global MASTER-Net observations report
  9. GRB 251024A: Swift-XRT refined Analysis
  10. GRB 251025A (sb25102501): stellar flare confirmed
  11. GRB 251025B: SVOM/VT optical observations with VHF data
  12. GRB 251025B: SVOM/C-GFT optical counterpart detection
  13. GRB 251025B: SVOM detection of a burst
  14. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  15. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 251025A: SVOM/VT VHF optical upper limit
  17. GRB 251025A: SVOM detection of a faint burst
  18. GRB 251024A: LCOGT Optical Afterglow Detection
  19. GRB 251024A: Swift detection of a burst
  20. Swift GRB 251024A: Global MASTER-Net observations report
  21. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  22. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  23. EP251023a: MAO/AZT-22 optical observations
  24. EP251023b/GRB 251023B: JinShan optical observation
  25. EP251023b: Global MASTER-Net observations report
  26. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  27. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  28. GRB 251022A: GROWTH-India Telescope optical observations
  29. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  30. EP251023a: GROWTH-India Telescope optical observations
  31. GRB 251022A: Fermi GBM Observation
  32. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  33. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  34. EP251023a: Global MASTER-Net observations report
  35. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  36. IPN triangulation of GRB 251016B
  37. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  38. EP#01709247298: Swift-XRT counterpart detection
  39. EP251023a: COLIBRÍ optical observations
  40. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  41. GRB 251022A: COLIBRÍ optical observations
  42. GRB 251013C: ISON-Castelgrande observatory optical observations
  43. GRB 251022A: MASTER OT detection
  44. GRB 251022A: DDOTI Optical Detection
  45. EP251021b/GRB 251021A: SVOM/VT optical candidate
  46. EP251023a: NOT optical counterpart detection
  47. Fermi GRB 251023A: Global MASTER-Net observations report
  48. EP251023a: GSP Optical Counterpart Detection
  49. EP251023a: Einstein Probe detection of an X-ray transient
  50. EP/WXT 01709247295: GOTO optical afterglow candidate.
  51. GRB 251022A: GOTO optical counterpart detection
  52. GRB 251023A: Fermi GBM Final Localization Correction
  53. GRB 251022A: Fermi-LAT detection
  54. GRB 251016B: Fermi GBM Detection
  55. LAT GRB251022A: Global MASTER-Net observations report
  56. GRB 251022A: Fermi GBM Final Real-time Localization
  57. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  58. EP251021b: BOOTES-7 optical upper limit
  59. EP251021b: Einstein Probe detection of a fast X-ray transient
  60. GRB 251016A: SVOM/ECLAIRs refined analysis
  61. GRB 251017A: COLIBRÍ optical observations of a late plateau
  62. IceCube-251018A: DDOTI Optical Upper Limit
  63. GRB 251017A: Swift-BAT refined analysis
  64. GRB 251016A: Fermi GBM Observation
  65. GRB 251018A: Fermi GBM Observation
  66. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  67. GRB 251018A: Swift-XRT refined Analysis
  68. Fermi trigger No 782500909: Global MASTER-Net observations report
  69. IceCube-251018A: Global MASTER-Net observations report
  70. GRB 251017A: Swift/UVOT Detection
  71. GRB 251016A: Swift/UVOT Detection
  72. GRB 251018A: Swift/UVOT Detection
  73. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  74. GRB 251016A: VLT/FORS2 Optical Observation
  75. GRB 251017A: COLIBRÍ photometric redshift
  76. GRB 251017A: Swift-XRT refined Analysis
  77. GRB 251018A: MASTER OT detection
  78. GRB 251018A: TRT optical afterglow detection
  79. Swift GRB 251018A: Global MASTER-Net observations report
  80. GRB 251018A: Swift detection of a burst with an optical counterpart
  81. GRB 251018A: Fermi GBM Final Real-time Localization
  82. GRB 251017A: SVOM/VT optical observation
  83. GRB 251011A: Fermi GBM Observation
  84. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  85. GRB 251017A: J-band detection with WINTER
  86. GRB 251013C: Liverpool Telescope observations
  87. GRB 251013C: Leavitt Observatory optical photometry
  88. Fermi GRB 251016B: Global MASTER-Net observations report
  89. GRB 251017A: JinShan observations of the optical afterglow
  90. Swift GRB 251017A: Global MASTER-Net observations report
  91. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  92. Swift Trigger 1404295 is not a GRB
  93. GRB 251017A: COLIBRÍ Early Afterglow Detection
  94. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  95. GRB 251017A: Swift detection of a burst with an optical counterpart
  96. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  97. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  98. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  99. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  100. GRB 251007B: Swift-BAT refined analysis

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