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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"

32543 results found.

  1. GRB 250926B: VZLUSAT-2 detection
  2. GRB 250926A: VZLUSAT-2 detection
  3. GRB 250925A: VZLUSAT-2 detection
  4. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  5. GRB 251026A/EP251026a: EP-FXT follow-up observation
  6. GRB 251028B: Fermi/GBM observation
  7. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  8. GRB 251028B: Glowbug gamma-ray detection
  9. GRB 251028A: Glowbug gamma-ray detection
  10. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  11. Fermi GRB 251028B: Global MASTER-Net observations report
  12. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  13. GRB251026B: PRIME H-band upper limit
  14. GRB251025B: 3.6m DOT Optical Observations
  15. SVOM trigger sb25102702/GRB 251027A is not a GRB
  16. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 251025B: Swift-XRT confirmation of fading
  18. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  19. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  20. GRB 251025C: Glowbug gamma-ray detection
  21. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  22. GRB 251023B: Swift-UVOT Upper Limits
  23. Konus-Wind detection of GRB 251022A
  24. GRB 251022A: SVOM/GRM observation
  25. GRB 251026B: Swift ToO observations
  26. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  27. GRB 251027A: LCO optical upper limit
  28. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  30. GRB 251023B / EP251023b: Mondy optical upper limit
  31. GRB 251017A: INASAN-Kislovodsk optical observations
  32. GRB 251026A: Mondy optical upper limit
  33. GRB 251025B: Mondy optical observations
  34. GRB 251025B: Kilonova-Catcher optical afterglow detection
  35. Konus-Wind detection of GRB 251016A (short/hard)
  36. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  37. GRB 251026B: Tentative GOTO optical counterpart candidate
  38. GRB 251025C: AstroSat CZTI detection
  39. EP251023a: Mondy optical observations
  40. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  41. GRB 251025B: MAO/AZT-22 optical observations
  42. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  43. Fermi GRB 251026B: Global MASTER-Net observations report
  44. Fermi GRB 251025C: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  46. GRB 251026A: Swift-XRT observations
  47. GRB 251025B: OHP/T193 optical detection
  48. GRB 251025B: J-band detection with WINTER
  49. GRB 251026A: SVOM/C-GFT upper limit
  50. IceCube-251025A: DDOTI Optical Upper Limit
  51. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB 251025B: SVOM/VT optical bump
  53. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  54. GRB 251023A: SVOM/GRM observation
  55. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  56. Konus-Wind detection of GRB 251016B
  57. GRB 251025B: GROWTH-India Telescope optical observations
  58. GRB 251024A: Swift/UVOT Upper Limits
  59. GRB 251025B: Swift-XRT afterglow detection
  60. GRB 251024A: Swift-BAT refined analysis
  61. GRB 251025A (sb25102501): stellar flare confirmed
  62. GRB 251025B: SVOM/VT optical observations with VHF data
  63. GRB 251025B: MASTER OT detection
  64. GRB 251025B: SVOM/C-GFT optical counterpart detection
  65. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  66. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB 251025A: SVOM/VT VHF optical upper limit
  68. GRB 251003A: VLA Detection
  69. GRB 251023C: Glowbug gamma-ray detection
  70. GRB 251024A: LCOGT Optical Afterglow Detection
  71. GRB 251022A: KAIT optical observations
  72. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  73. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  74. EP251023a: MAO/AZT-22 optical observations
  75. GRB 251023B: OHP/T193 optical observations
  76. EP251023a: OHP/T193 optical observations
  77. GRB 251023C: AstroSat CZTI detection
  78. EP251023b/GRB 251023B: JinShan optical observation
  79. GRB 251022A: Swift-XRT detection of GOTO25iym
  80. EP251023b: Global MASTER-Net observations report
  81. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  82. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  83. GRB 251022A: GROWTH-India Telescope optical observations
  84. EP251023a: GROWTH-India Telescope optical observations
  85. GRB 251022A: Fermi GBM Observation
  86. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  87. GRB 251023A: Glowbug gamma-ray detection
  88. GRB 251023B: Glowbug gamma-ray detection
  89. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  90. EP251023a: Global MASTER-Net observations report
  91. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  92. IPN triangulation of GRB 251016B
  93. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  94. EP#01709247298: Swift-XRT counterpart detection
  95. EP251023a: COLIBRÍ optical observations
  96. GRB 251013C: further SAO RAS optical observations
  97. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  98. GRB 251022A: COLIBRÍ optical observations
  99. GRB 251013C: ISON-Castelgrande observatory optical observations
  100. GRB 251022A: MASTER OT detection

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