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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"

4295 results found.

  1. EP261030a: GROWTH-India Telescope Upper Limit
  2. The EP-WXT trigger 01709321980: KAIT confirmation of a stellar flare
  3. GRB 261029A: Glowbug gamma-ray detection
  4. GRB 261026A: Mondy, SAO RAS and Terskol optical observations
  5. EP Alert 261030.22: Global MASTER-Net observations report
  6. GRB 261029A: ULL-ASTRO-MASTER observations with LCO 1-m telescope at Siding Spring Observatory
  7. GRB 261029A: Ondrejov D50 optical observations, possible rebrightening
  8. GRB 261029A: Liverpool Telescope observations
  9. GRB 261029A: Fermi GBM Observation
  10. GRB 261029A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 261029B : AstroSat CZTI detection
  12. GRB 261029A / AT2026ahaw: r- and i-band optical follow-up with the PKU 60cm Telescope
  13. GRB 261029A : AstroSat CZTI detection
  14. GRB 261029A: EP-FXT follow-up observation
  15. GRB 261029A: LCO optical observations (correction to GCN 46082)
  16. GRB 261029A: SVOM/COLIBRÍ (FM-GFT) optical observations
  17. GRB 261029A: LCO optical observations
  18. GRB 261029A: NOT imaging and spectroscopic redshift z = 3.27
  19. GRB 261029A: KAIT optical observations
  20. GRB 261029B: Fermi GBM Final Real-time Localization
  21. GRB 261029A: GOTO optical counterpart candidate
  22. GRB 261029A: Fermi GBM Final Real-time Localization
  23. GRB 261026A: SVOM/VT optical observations
  24. Fermi GRB 261026B: Global MASTER-Net observations report
  25. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  26. EP 261025a: COLIBRÍ optical upper limit
  27. EP261015a: VLA non-detection
  28. EP261015a: GSP multiband optical follow-up observations
  29. EP261015a: Follow-up with the 1.3m DFOT
  30. GRB 261020A: MAXI GSC detection
  31. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  32. EP261015c: Einstein Probe detection of a fast X-ray transient
  33. GRB 261011A: Swift-BAT refined analysis
  34. MAXI GRB261012.23: Global MASTER-Net observations report
  35. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  36. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  37. EP261010a: Global MASTER-Net observations report
  38. EP261003a: J-band upper limit with WINTER
  39. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  40. IceCube Alert 260930A: Global MASTER-Net observations report
  41. EP260927a: Global MASTER-Net observations report
  42. EP260924a: Global MASTER-Net observations report
  43. Fermi GRB 260926C: Global MASTER-Net observations report
  44. GRB 260921A: NuSTAR detection of prompt emission
  45. GRB 260921A: SVOM/GRM observation
  46. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  47. Konus-Wind detection of GRB 260921A (possible merger-origin)
  48. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  49. GRB 260921A: AstroSat CZTI detection
  50. GRB 260921A: Fermi GBM Observation
  51. GRB 260921A: Swift detection of a burst
  52. GRB 260921A: Fermi GBM Final Real-time Localization
  53. EP260920b: COLIBRÍ optical observations
  54. EP Alert 260921.01: Global MASTER-Net observations report
  55. The EP-WXT trigger 01709318491 is likely a flaring star
  56. IPN triangulation of GRB 260810A
  57. EP Alert 260917.32: Global MASTER-Net observations report
  58. Fermi trigger No 811264269: Global MASTER-Net observations report
  59. EP Alert 260914.53: Global MASTER-Net observations report
  60. GRB 260914A: SVOM/C-GFT optical observations
  61. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  62. SVOM GRB260914.47: Global MASTER-Net observations report
  63. Fermi trigger No 810554827: Global MASTER-Net observations report
  64. The EP-WXT trigger 01709302592 is likely a flaring star
  65. NuSTAR Transient 260828: SOAR Optical Upper Limits
  66. GRB 260829A: AstroSat CZTI detection
  67. EP260830a: Global MASTER-Net observations report
  68. GRB 260829A: Fermi GBM Detection
  69. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  70. GRB 260829A: Fermi GBM Final Real-time Localization
  71. Fermi GBM trigger 809666623/260829141 is not a GRB
  72. MAXI GRB260827.40: Global MASTER-Net observations report
  73. IceCube Alert 260825A: Global MASTER-Net observations report
  74. GRB 260818B: VLA radio observations
  75. GRB 260818B: SVOM/GRM observation
  76. EP260812a: AZT-22 optical upper limit
  77. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  78. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  79. GRB 260809A: NOT optical observations
  80. EP260809a: J-band upper limit with WINTER
  81. GRB 260808B: LCO optical observations
  82. Fermi GRB 260808A: Global MASTER-Net observations report
  83. SN 2026stf / GRB 260708A: ATLAS forced photometry
  84. Fermi GRB 260802B: Global MASTER-Net observations report
  85. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  86. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  87. EP260723a: SVOM/VT optical observation
  88. Fermi GRB 260718A: Global MASTER-Net observations report
  89. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  90. EP260711a: EP-FXT follow-up observation
  91. GRB 260629A: AstroSat CZTI detection
  92. GRB 260703A: Fermi GBM Final Localization
  93. Fermi trigger No 804552016: Global MASTER-Net observations report
  94. GRB 260629A: Fermi GBM Final Real-time Localization
  95. Fermi GRB 260628A: Global MASTER-Net observations report
  96. EP260623a: TNG NIR afterglow detection
  97. EP260623a: WINTER J-band observations
  98. GRB 260619A: SVOM possible detection of a faint burst
  99. GRB 260506B: cubesat Avion detection
  100. GRB 260429A: cubesat Avion detection

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