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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"

5051 results found.

  1. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  2. EP260223a: COLIBRÍ optical upper limits
  3. GRB 260223A: SVOM/VT optical observation
  4. EP260221a: Optical upper limit with Kinder observations
  5. GRB 260223A: DDOTI Optical Candidate
  6. Fermi GRB 260223A: Global MASTER-Net observations report
  7. IceCube Alert 260217A: Global MASTER-Net observations report
  8. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  9. EP260214b: LCO optical counterpart detection
  10. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  11. GRB 260212A: GECAM-B observation
  12. GRB 260211A - SVOM/ECLAIRs refined analysis
  13. GRB 260210A: SVOM/GRM observation
  14. Fermi GBM Sub-Threshold Detection of GRB 260211A
  15. GRB 260211A: SVOM detection of a burst
  16. Konus-Wind detection of GRB 260209B
  17. Konus-Wind detection of GRB 260127B
  18. EP260210a: Global MASTER-Net observations report
  19. EP260210a: refined analysis of the EP-FXT observation
  20. GRB 260208B: AstroSat CZTI detection of a bright long burst
  21. Fermi GRB 260209A: Global MASTER-Net observations report
  22. Fermi GRB 260208D: Global MASTER-Net observations report
  23. Fermi GRB 260208A: Global MASTER-Net observations report
  24. GRB 260131A/B: Mondy and Terskol optical observations
  25. GRB 260206A: Swift-XRT observations
  26. Fermi trigger No 792135758: Global MASTER-Net observations report
  27. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  28. GRB 251230A: MeerLICHT afterglow detection
  29. GRB 260131A: NOT spectroscopic redshift z = 1.434
  30. EP260131a: COLIBRÍ observations of slow optical fading
  31. Fermi GRB 260130A: Global MASTER-Net observations report
  32. Fermi GRB 260129A: Global MASTER-Net observations report
  33. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 260127A: COLIBRÍ optical observations
  35. GRB 260125A: GOTO candidate optical counterpart
  36. GRB 260120A: AstroSat CZTI detection
  37. SVOM GRB260121.06: Global MASTER-Net observations report
  38. GRB 260120B: Swift detection of a burst
  39. EP260119a: Liverpool Telescope optical follow-up observations
  40. EP260119a: Global MASTER-Net observations report
  41. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  42. EP260116a: Einstein Probe detection of an X-ray transient
  43. Fermi GRB 260115A: Global MASTER-Net observations report
  44. GRB 251222A: radio detection with the VLA
  45. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  46. GRB 260114A: Swift-XRT refined Analysis
  47. GRB 260109A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 260107A: Global MASTER-Net observations report
  49. Fermi GRB 260105B: Global MASTER-Net observations report
  50. Fermi GRB 260104B: Global MASTER-Net observations report
  51. GRB 260104A: Swift-XRT refined Analysis
  52. GRB 260101A: Swift-XRT refined Analysis
  53. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  54. GRB 251230A: Swift-XRT refined Analysis
  55. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  56. EP251229a: Global MASTER-Net observations report
  57. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  58. Fermi GRB 251228A: Global MASTER-Net observations report
  59. SVOM GRB251227.07: Global MASTER-Net observations report
  60. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  61. IceCube Alert 251225.84: Global MASTER-Net observations report
  62. EP251222a: Optical upper limit with Kinder observations
  63. GRB 251222A/EP251222b: FTW optical and NIR observations
  64. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  65. EP251222a: Global MASTER-Net observations report
  66. GRB 251222A: Swift-XRT afterglow detection
  67. IPN triangulation of GRB 251220B (short)
  68. GRB 251221A: Swift-XRT refined Analysis
  69. GRB 251221A: Fermi GBM Observation
  70. GRB 251221A: Swift detection of a burst
  71. GRB 251221A: Fermi GBM Final Real-time Localization
  72. GRB 251220A: MAXI/GSC detection
  73. Fermi GRB 251217A: Global MASTER-Net observations report
  74. Fermi GRB 251215A: Global MASTER-Net observations report
  75. EP251214a: Optical upper limit with Kinder observations
  76. GRB 251209A: GECAM-B observation of a long burst
  77. GRB 251214D: GECAM-B observation of a long burst
  78. GRB 251209A: Insight-HXMT/HE detection
  79. GRB 251214B: Swift-XRT refined Analysis
  80. GRB 251214D: AstroSat CZTI detection of a long burst
  81. Fermi trigger No 787396657: Global MASTER-Net observations report
  82. GRB 251214B: SVOM/C-GFT optical observations
  83. Fermi GRB 251214A: Global MASTER-Net observations report
  84. EP251212a: Global MASTER-Net observations report
  85. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  86. GRB 251209A: NuSTAR detection of prompt emission
  87. GRB 251209A: Fermi GBM observation
  88. GRB 251209A: AstroSat CZTI detection
  89. EP251124a: Mondy optical upper limit
  90. GRB 251209A: Fermi GBM Final Real-time Localization
  91. GRB 251203A: SVOM/GRM observation
  92. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  93. GRB 251202A / EP251202a: SVOM/VT optical observation
  94. Fermi GRB 251202B: Global MASTER-Net observations report
  95. GRB 251202A: Swift-XRT afterglow detection
  96. GRB 251201B: Swift-XRT refined Analysis
  97. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  98. GRB 251201B: Fermi GBM Final Real-time Localization
  99. EP251130A: Optical observation from 1.3m DFOT
  100. GRB 251201A: MAXI/GSC detection

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