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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"

32707 results found.

  1. GRB 260208C: AstroSat CZTI detection
  2. EP260210a: COLIBRÍ optical upper limit
  3. EP260210a: SVOM/C-GFT upper limit
  4. GRB 260208B: refined analysis of the EP-FXT observation
  5. GRB 260207B: AstroSat CZTI detection
  6. GRB 260208C: SVOM/GRM observation
  7. GRB 260204A: Swift-XRT afterglow detection
  8. GRB 260208B: AstroSat CZTI detection of a bright long burst
  9. GRB260208A: Liverpool Telescope optical follow-up observations
  10. GRB 260208A: Glowbug gamma-ray detection
  11. GRB 260208A: NuSTAR detection of prompt emission
  12. GRB 260208A: Fermi GBM Observation
  13. Fermi GRB 260209A: Global MASTER-Net observations report
  14. GRB 260208B: Swift-XRT observations
  15. GRB 260131A/B: continued Mondy optical observations
  16. GRB 260204A: Swift/UVOT Upper Limits
  17. GRB 260208B: COLIBRÍ optical observations
  18. GRB 260208A: Mondy optical observations (duplicate submission)
  19. GRB 260208A: Mondy optical observations
  20. GRB 260208A: 1.3m DFOT optical detection
  21. GRB 260208A: COLIBRÍ optical observations
  22. GRB 260208B: EP-FXT observation
  23. GRB 260208A: NOT spectroscopic redshift z = 2.36
  24. GRB 260208A: Liverpool Telescope optical detection
  25. Fermi GRB 260208C: Global MASTER-Net observations report
  26. GRB 260208B: SVOM/VT optical candidate
  27. GRB 260208A: GECAM-B observation of a bright burst
  28. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  29. GRB 260208A: SVOM/VT optical observation
  30. Fermi GRB 260208D: Global MASTER-Net observations report
  31. GRB 260208A: Swift-XRT observations
  32. GRB 260208B: Swift ToO observations
  33. GRB 260208B: SVOM/GRM observation of a bright burst
  34. GRB 260208B: Fermi GBM Detection
  35. GRB 260208B: Fermi-LAT detection
  36. GRB 260208A: Fermi-LAT detection
  37. GRB 260207B: GECAM-B observation
  38. GRB 260208A: Swift ToO observations
  39. GRB 260208A: Fermi GBM Classification Correction
  40. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  41. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  42. Fermi GRB 260208A: Global MASTER-Net observations report
  43. GRB 260207A : MASTER optical counterpart discovery
  44. GRB 260131A/B: Mondy and Terskol optical observations
  45. Fermi GRB 260207B: Global MASTER-Net observations report
  46. GRB 260206A: Swift-XRT observations
  47. EP260131a: VLA detection
  48. GRB 260206A: Tiled Swift observations
  49. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  50. GRB 260204A: Swift-XRT observations
  51. GRB 260204A: LCO optical afterglow detection
  52. GRB 260204A: SVOM/VT optical candidate
  53. GRB 260204A : MASTER Global robotic net optical observations
  54. Fermi GBM Sub-Threshold Detection of GRB 260204A
  55. GRB 260204A: GOTO optical upper limit
  56. GRB 260204A: LCO optical upper limits
  57. EP260110a: Late GTC/EMIR near-infrared observations
  58. GRB 260121A: 239Alferov CubeSat detection
  59. Konus-Wind detection of GRB 260121A
  60. GRB 260131A/B: OHP/T193 optical observations
  61. GRB 260131A: KAIT optical observations
  62. GRB 251230A: MeerLICHT afterglow detection
  63. GRB 260131A: FTW optical and NIR observations
  64. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  65. GRID detection of GRB 260131A/B
  66. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  67. GRB 260130A: Insight-HXMT/HE detection
  68. GRB 260130A: GECAM-B observation of a short burst
  69. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  70. GRB 260131A/B: EP/FXT X-ray afterglow detection
  71. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  72. GRB 260127B: Insight-HXMT/HE detection
  73. GRB 260127B: GECAM-B observation of a short burst
  74. GRB 260127A: GECAM-B observation
  75. GRB 260131A: NOT spectroscopic redshift z = 1.434
  76. EP260131a: Liverpool Telescope optical upper limits
  77. EP260131a: COLIBRÍ further observations
  78. Konus-Wind detection of GRB 260128A / EP260128a
  79. GRB 260131A: Insight-HXMT/HE detection
  80. Konus-Wind detection of GRB 260131A/B
  81. EP260131a: SVOM/VT optical observation
  82. EP260131a: Xinglong optical upper limit
  83. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  84. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  85. GRB 260131A/B: Fermi GBM Observation
  86. EP260131a: COLIBRÍ observations of slow optical fading
  87. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  89. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  90. EP260131a: COLIBRÍ optical observations of the counterpart
  91. GRB 260127B: AstroSat CZTI detection
  92. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  93. Fermi GRB 260130A: Global MASTER-Net observations report
  94. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  95. Fermi GRB 260129A: Global MASTER-Net observations report
  96. GRB 260128B: LCO optical upper limits
  97. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  98. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  99. IPN triangulation of GRB 260121A
  100. GRB 260127A: Swift-BAT refined analysis

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