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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"

5117 results found.

  1. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  3. MAXI GRB260827.40: Global MASTER-Net observations report
  4. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  5. EP260822a: Global MASTER-Net observations report
  6. GRB 260809A: SVOM/ECLAIRs refined analysis
  7. IceCube Alert 260825A: Global MASTER-Net observations report
  8. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  10. GRB 260820A: Insight-HXMT/HE detection
  11. GRB260820A: Fermi GBM Final Real-Time Localization
  12. GRB 260818B: NOT optical upper limits
  13. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 260808B: SVOM/VT optical afterglow confirmation
  15. GRB 260808C: Fermi GBM Final Real-time Localization
  16. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  17. SN 2026stf / GRB 260708A: ATLAS forced photometry
  18. Fermi GRB 260802B: Global MASTER-Net observations report
  19. EP260731a: Einstein Probe detection of an X-ray transient
  20. GRB260730A: Fermi GBM Final Localization
  21. EP260728a: COLIBRÍ optical upper limit
  22. Fermi GRB 260726A: Global MASTER-Net observations report
  23. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  24. GRB 260602B: cubesat Avion detection
  25. EP260723a: EP-FXT follow-up observation
  26. IPN triangulation of GRB 260706B
  27. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  28. EP260723a: Liverpool Telescope likely optical counterpart
  29. Fermi trigger No 806104130: Global MASTER-Net observations report
  30. IceCube Alert 260709A: Global MASTER-Net observations report
  31. GRB 260705B: SVOM/GRM observation
  32. EP260707a: Einstein Probe detection of an X-ray transient
  33. GRB 260706A: SVOM/ECLAIRs refined analysis
  34. GRB 260704A: SVOM detection of a possible GRB
  35. Fermi GRB 260703A: Global MASTER-Net observations report
  36. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  37. Fermi trigger No 804552016: Global MASTER-Net observations report
  38. GRB 260628A: Fermi GBM Final Real-time Localization
  39. EP260626a: Liverpool Telescope upper limits
  40. EP260623a: Liverpool Telescope optical observations
  41. Fermi GBM trigger 804010507/260624677 is not a GRB
  42. GRB 260624A: Fermi GBM Final Real-time Localization
  43. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  44. GRB 260623A: Fermi GBM Final Real-time Localization
  45. The EP-WXT trigger 01709271197 is likely a flaring star
  46. GRB 260604A: 239Alferov CubeSat detection
  47. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  48. GRB 260429A: cubesat Avion detection
  49. GRB260616C: MAXI/GSC detection
  50. EP260610b: MAO/AZT-22 optical observations
  51. GRB 260610A: Fermi GBM Final Real-time Localization
  52. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  53. GRB 260604A: SVOM/GRM detection
  54. GRB 260604C: 6 GHz VLA observations
  55. GRB 260604A: Glowbug gamma-ray detection
  56. Fermi GRB 260604C: Global MASTER-Net observations report
  57. Fermi GRB 260604C: Global MASTER-Net observations report
  58. GRB 260604A: Fermi GBM Final Real-time Localization
  59. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  60. Fermi GRB 260602B: Global MASTER-Net observations report
  61. Fermi GRB 260602B: Global MASTER-Net observations report
  62. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  63. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  64. Fermi GRB 260601A: Global MASTER-Net observations report
  65. Fermi trigger No 801900520: Global MASTER-Net observations report
  66. GRB 260531B: Fermi GBM Final Real-time Localization
  67. IPN triangulation of GRB 260527A / EP260527a
  68. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  69. Fermi trigger No 801580882: Global MASTER-Net observations report
  70. Fermi GRB 260526A: Global MASTER-Net observations report
  71. Fermi GRB 260522A: Global MASTER-Net observations report
  72. GRB 260511A: iTelescope T-75 optical detection
  73. GRB 260520A: Fermi GBM Final Localization
  74. Konus-Wind detection of GRB 260518A
  75. GRB 260421B: radio detection with the VLA
  76. Fermi GRB 260516C: Global MASTER-Net observations report
  77. Fermi GRB 260516B: Global MASTER-Net observations report
  78. SVOM GRB 260515A: Global MASTER-Net observations report
  79. EP260514a: Global MASTER-Net observations report
  80. GRB 260513A: Fermi GBM Final Real-time Localization
  81. Konus-Wind detection of GRB 260511B
  82. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  83. GRB 260511B: SAO RAS optical observations
  84. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  85. GRB 260510C: AstroSat CZTI detection
  86. Fermi GRB 260511A: Global MASTER-Net observations report
  87. GRB 260511A: LCO optical afterglow detection
  88. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  89. GRB 260510C: MAXI/GSC detection
  90. SVOM GRB 260509A: MASTER-OAFA optical observation
  91. Fermi GRB 260510A: Global MASTER-Net observations report
  92. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  93. EP260502a is likely a flaring star
  94. GRB 260421B: radio observation with the VLA
  95. IPN triangulation of GRB 260429A
  96. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  97. GRB 260429A: SVOM/GRM observation of a short burst
  98. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  99. GRB 260424B: AstroSat CZTI detection
  100. GRB 260429A: Fermi GBM Detection

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