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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32763 results found.

  1. GRB 251102A: AstroSat CZTI detection
  2. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  3. GRB 251103A: NOT spectroscopic redshift z = 0.76
  4. GRB 251103A: LCO optical afterglow detection
  5. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  6. GRB 251103A: NOT optical afterglow candidate
  7. Fermi GRB 251102A: Global MASTER-Net observations report
  8. GRB 251031A: Fermi GBM Observation
  9. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  10. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  11. Konus-Wind detection of GRB 251028A
  12. GRB 251025C: SVOM/GRM observation
  13. GRB 251028A: GECAM-B detection
  14. GRB 251028A: SVOM/GRM observation
  15. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  16. GRB 251028A: Fermi GBM Observation
  17. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  18. GRB 251022A: Swift-XRT confirmation of fading
  19. GRB 251026B: LBT near-infrared observations
  20. GRB 250926B: VZLUSAT-2 detection
  21. GRB 250926A: VZLUSAT-2 detection
  22. GRB 250925A: VZLUSAT-2 detection
  23. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  24. GRB 251026A/EP251026a: EP-FXT follow-up observation
  25. GRB 251028B: Fermi/GBM observation
  26. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  27. GRB 251028B: Glowbug gamma-ray detection
  28. GRB 251028A: Glowbug gamma-ray detection
  29. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  30. Fermi GRB 251028B: Global MASTER-Net observations report
  31. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  32. GRB251026B: PRIME H-band upper limit
  33. GRB251025B: 3.6m DOT Optical Observations
  34. SVOM trigger sb25102702/GRB 251027A is not a GRB
  35. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 251025B: Swift-XRT confirmation of fading
  37. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  38. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  39. GRB 251025C: Glowbug gamma-ray detection
  40. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  41. GRB 251023B: Swift-UVOT Upper Limits
  42. Konus-Wind detection of GRB 251022A
  43. GRB 251022A: SVOM/GRM observation
  44. GRB 251026B: Swift ToO observations
  45. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  46. GRB 251027A: LCO optical upper limit
  47. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  49. GRB 251023B / EP251023b: Mondy optical upper limit
  50. GRB 251017A: INASAN-Kislovodsk optical observations
  51. GRB 251026A: Mondy optical upper limit
  52. GRB 251025B: Mondy optical observations
  53. GRB 251025B: Kilonova-Catcher optical afterglow detection
  54. Konus-Wind detection of GRB 251016A (short/hard)
  55. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  56. GRB 251026B: Tentative GOTO optical counterpart candidate
  57. GRB 251025C: AstroSat CZTI detection
  58. EP251023a: Mondy optical observations
  59. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  60. GRB 251025B: MAO/AZT-22 optical observations
  61. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  62. Fermi GRB 251026B: Global MASTER-Net observations report
  63. Fermi GRB 251025C: Global MASTER-Net observations report
  64. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  65. GRB 251026A: Swift-XRT observations
  66. GRB 251025B: OHP/T193 optical detection
  67. GRB 251025B: J-band detection with WINTER
  68. GRB 251026A: SVOM/C-GFT upper limit
  69. IceCube-251025A: DDOTI Optical Upper Limit
  70. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. GRB 251025B: SVOM/VT optical bump
  72. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  73. GRB 251023A: SVOM/GRM observation
  74. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  75. Konus-Wind detection of GRB 251016B
  76. GRB 251025B: GROWTH-India Telescope optical observations
  77. GRB 251024A: Swift/UVOT Upper Limits
  78. GRB 251025B: Swift-XRT afterglow detection
  79. GRB 251024A: Swift-BAT refined analysis
  80. GRB 251025A (sb25102501): stellar flare confirmed
  81. GRB 251025B: SVOM/VT optical observations with VHF data
  82. GRB 251025B: MASTER OT detection
  83. GRB 251025B: SVOM/C-GFT optical counterpart detection
  84. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  85. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB 251025A: SVOM/VT VHF optical upper limit
  87. GRB 251003A: VLA Detection
  88. GRB 251023C: Glowbug gamma-ray detection
  89. GRB 251024A: LCOGT Optical Afterglow Detection
  90. GRB 251022A: KAIT optical observations
  91. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  92. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  93. EP251023a: MAO/AZT-22 optical observations
  94. GRB 251023B: OHP/T193 optical observations
  95. EP251023a: OHP/T193 optical observations
  96. GRB 251023C: AstroSat CZTI detection
  97. EP251023b/GRB 251023B: JinShan optical observation
  98. GRB 251022A: Swift-XRT detection of GOTO25iym
  99. EP251023b: Global MASTER-Net observations report
  100. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient

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