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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"

42470 results found.

  1. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  2. GRB 260310A / AT 2026fgk: iTelescope optical observations
  3. EP260314a: COLIBRÍ optical upper limit
  4. GRID detection of GRB 260312B
  5. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  6. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  7. EP260314a: BOOTES-6/DPR optical upper limits at early times
  8. EP260314a: Global MASTER-Net observations report
  9. EP260314a: SVOM/VT optical candidate
  10. Fermi trigger No 795185313: Global MASTER-Net observations report
  11. IceCube Alert 260315A: Global MASTER-Net observations report
  12. EP260314a: Einstein Probe detection of an X-ray transient
  13. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  14. GRB 260314A: GECAM-B observation of a burst
  15. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  16. GRB 260310A / AT2026fgk: SAO RAS optical observations
  17. GRB 260310A/AT2026fgk: radio detection at 15GHz
  18. GRB 260310A / AT2026fgk: TNG NIR detection
  19. GRB 260310A / AT2026fgk: OASDG optical observations
  20. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  21. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  22. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  23. Fermi GRB 260314A: Global MASTER-Net observations report
  24. Fermi GRB 260313A: Global MASTER-Net observations report
  25. GRB 260314A: Fermi GBM Final Real-time Localization
  26. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  27. GRB 260313A: A Correction to the Fermi GBM Final Localization
  28. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  29. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  30. GRB 260310B: Insight-HXMT/HE detection
  31. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  32. GRB 260310A: NOT optical polarimetry
  33. GRB 260312B: AstroSat CZTI detection
  34. Swift BAT trigger 1500295: A solar flare
  35. GRB 260313A: Fermi GBM Final Real-time Localization
  36. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  37. Swift BAT trigger 1500287: A solar flare
  38. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  39. GRB 260308A: Insight-HXMT/HE detection
  40. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  41. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  42. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  43. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  44. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  45. GRB260310A / AT2026fgk: P200 Spectroscopy
  46. GRB 260312B: Glowbug gamma-ray detection
  47. GRB 260310A: Fermi GBM Observation
  48. GRB 260310A: potential optical counterpart
  49. Fermi GRB 260312B: Global MASTER-Net observations report
  50. Fermi GRB 260311B: Global MASTER-Net observations report
  51. Swift BAT trigger 1500148: A solar flare
  52. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  53. GRB 260312B: Fermi GBM Final Real-time Localization
  54. The EP-WXT trigger 01709258843 is not a real source
  55. GRB 260310B: GECAM-B observation of a burst
  56. Retraction of GCN 43965: GRB is actually solar flare
  57. GRB 260312A: Swift detection of a burst
  58. GRB 260311B: Fermi GBM Final Real-time Localization
  59. GRB 260131A/B: radio detection with the VLA
  60. EP260302a: MeerKAT radio counterpart
  61. GRB260307A: GECAM-B observation of a burst
  62. GRB 260308A: SVOM/GRM observation of a short GRB
  63. EP260306a: Mondy optical upper limit
  64. GRB 260310A: AstroSat CZTI detection of a long burst
  65. GRB 260311A: Fermi GBM Final Real-time Localization
  66. Fermi GRB 260310B: Global MASTER-Net observations report
  67. GRB 260310B: Fermi GBM Final Real-time Localization
  68. Fermi GRB 260310A: Global MASTER-Net observations report
  69. GRB 260307B: SVOM/ECLAIRs refined analysis
  70. GRB 260208A: radio detection with the VLA
  71. GRB 260310A: Fermi GBM Final Real-time Localization
  72. GRB 260307A: Glowbug gamma-ray detection
  73. GRB 260308A: Fermi GBM Final Real-time Localization
  74. Fermi GBM Sub-Threshold Detection of GRB 260307B
  75. GRB 260307B: Mephisto optical upper limits
  76. GRB 260307B: possible NOT optical counterpart
  77. GRB 260307B: SVOM/VT upper limit with X band data analysis
  78. Fermi GRB 260307A: Global MASTER-Net observations report
  79. GRB260307B: GROWTH-India Telescope optical upper limit
  80. GRB 260307B: SVOM/VT optical candidate
  81. GRB 260307B: SVOM/C-GFT upper limit
  82. GRB 260307B: SVOM detection of a burst
  83. GRB 260307A: Fermi GBM Final Localization
  84. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  85. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  86. GRB 260207A: TESS Detection and Possible VLA Counterpart
  87. EP260302a: SVOM/VT optical observation
  88. EP260306a: Gemini-North redshift z = 4.773
  89. EP260306a: SVOM/VT optical observation
  90. EP260302a: Gemini-South redshift z = 1.535
  91. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  92. EP260306a: Einstein Probe detection of an X-ray transient
  93. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  94. EP260302a: Optical afterglow rebrightening
  95. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  96. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  97. GRB 260303A: 1.3m DFOT optical upper limit
  98. EP260214b: ATCA 6 GHz observations
  99. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  100. GRB 260303A: SVOM/ECLAIRs refined analysis

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