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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"

32535 results found.

  1. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  2. Fermi GRB 251028B: Global MASTER-Net observations report
  3. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  4. GRB251026B: PRIME H-band upper limit
  5. GRB251025B: 3.6m DOT Optical Observations
  6. SVOM trigger sb25102702/GRB 251027A is not a GRB
  7. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 251025B: Swift-XRT confirmation of fading
  9. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  10. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  11. GRB 251025C: Glowbug gamma-ray detection
  12. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  13. GRB 251023B: Swift-UVOT Upper Limits
  14. Konus-Wind detection of GRB 251022A
  15. GRB 251022A: SVOM/GRM observation
  16. GRB 251026B: Swift ToO observations
  17. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  18. GRB 251027A: LCO optical upper limit
  19. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  21. GRB 251023B / EP251023b: Mondy optical upper limit
  22. GRB 251017A: INASAN-Kislovodsk optical observations
  23. GRB 251026A: Mondy optical upper limit
  24. GRB 251025B: Mondy optical observations
  25. GRB 251025B: Kilonova-Catcher optical afterglow detection
  26. Konus-Wind detection of GRB 251016A (short/hard)
  27. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  28. GRB 251026B: Tentative GOTO optical counterpart candidate
  29. GRB 251025C: AstroSat CZTI detection
  30. EP251023a: Mondy optical observations
  31. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  32. GRB 251025B: MAO/AZT-22 optical observations
  33. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  34. Fermi GRB 251026B: Global MASTER-Net observations report
  35. Fermi GRB 251025C: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  37. GRB 251026A: Swift-XRT observations
  38. GRB 251025B: OHP/T193 optical detection
  39. GRB 251025B: J-band detection with WINTER
  40. GRB 251026A: SVOM/C-GFT upper limit
  41. IceCube-251025A: DDOTI Optical Upper Limit
  42. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 251025B: SVOM/VT optical bump
  44. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  45. GRB 251023A: SVOM/GRM observation
  46. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  47. Konus-Wind detection of GRB 251016B
  48. GRB 251025B: GROWTH-India Telescope optical observations
  49. GRB 251024A: Swift/UVOT Upper Limits
  50. GRB 251025B: Swift-XRT afterglow detection
  51. GRB 251024A: Swift-BAT refined analysis
  52. GRB 251025A (sb25102501): stellar flare confirmed
  53. GRB 251025B: SVOM/VT optical observations with VHF data
  54. GRB 251025B: MASTER OT detection
  55. GRB 251025B: SVOM/C-GFT optical counterpart detection
  56. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  57. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 251025A: SVOM/VT VHF optical upper limit
  59. GRB 251003A: VLA Detection
  60. GRB 251023C: Glowbug gamma-ray detection
  61. GRB 251024A: LCOGT Optical Afterglow Detection
  62. GRB 251022A: KAIT optical observations
  63. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  64. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  65. EP251023a: MAO/AZT-22 optical observations
  66. GRB 251023B: OHP/T193 optical observations
  67. EP251023a: OHP/T193 optical observations
  68. GRB 251023C: AstroSat CZTI detection
  69. EP251023b/GRB 251023B: JinShan optical observation
  70. GRB 251022A: Swift-XRT detection of GOTO25iym
  71. EP251023b: Global MASTER-Net observations report
  72. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  73. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  74. GRB 251022A: GROWTH-India Telescope optical observations
  75. EP251023a: GROWTH-India Telescope optical observations
  76. GRB 251022A: Fermi GBM Observation
  77. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  78. GRB 251023A: Glowbug gamma-ray detection
  79. GRB 251023B: Glowbug gamma-ray detection
  80. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  81. EP251023a: Global MASTER-Net observations report
  82. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  83. IPN triangulation of GRB 251016B
  84. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  85. EP#01709247298: Swift-XRT counterpart detection
  86. EP251023a: COLIBRÍ optical observations
  87. GRB 251013C: further SAO RAS optical observations
  88. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  89. GRB 251022A: COLIBRÍ optical observations
  90. GRB 251013C: ISON-Castelgrande observatory optical observations
  91. GRB 251022A: MASTER OT detection
  92. GRB 251022A: DDOTI Optical Detection
  93. EP251021b/GRB 251021A: SVOM/VT optical candidate
  94. EP251023a: NOT optical counterpart detection
  95. Fermi GRB 251023A: Global MASTER-Net observations report
  96. EP251023a: GSP Optical Counterpart Detection
  97. EP251023a: Einstein Probe detection of an X-ray transient
  98. GRB 251022A: GOTO optical counterpart detection
  99. GRB 251022A: Fermi-LAT detection
  100. GRB 251022A: Tiled Swift observations

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