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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"

29076 results found.

  1. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  2. EP260314a: BOOTES-6/DPR optical upper limits at early times
  3. EP260314a: Global MASTER-Net observations report
  4. EP260314a: SVOM/VT optical candidate
  5. Fermi trigger No 795185313: Global MASTER-Net observations report
  6. IceCube Alert 260315A: Global MASTER-Net observations report
  7. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  8. GRB 260314A: GECAM-B observation of a burst
  9. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  10. GRB 260310A / AT2026fgk: SAO RAS optical observations
  11. GRB 260310A/AT2026fgk: radio detection at 15GHz
  12. GRB 260310A / AT2026fgk: TNG NIR detection
  13. GRB 260310A / AT2026fgk: OASDG optical observations
  14. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  15. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  16. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  17. Fermi GRB 260314A: Global MASTER-Net observations report
  18. Fermi GRB 260313A: Global MASTER-Net observations report
  19. GRB 260314A: Fermi GBM Final Real-time Localization
  20. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  21. GRB 260313A: A Correction to the Fermi GBM Final Localization
  22. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  23. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  24. GRB 260310B: Insight-HXMT/HE detection
  25. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  26. GRB 260310A: NOT optical polarimetry
  27. GRB 260312B: AstroSat CZTI detection
  28. Swift BAT trigger 1500295: A solar flare
  29. GRB 260313A: Fermi GBM Final Real-time Localization
  30. Swift BAT trigger 1500287: A solar flare
  31. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  32. GRB 260308A: Insight-HXMT/HE detection
  33. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  34. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  35. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  36. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  37. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  38. GRB260310A / AT2026fgk: P200 Spectroscopy
  39. GRB 260312B: Glowbug gamma-ray detection
  40. GRB 260310A: Fermi GBM Observation
  41. GRB 260310A: potential optical counterpart
  42. Fermi GRB 260312B: Global MASTER-Net observations report
  43. Fermi GRB 260311B: Global MASTER-Net observations report
  44. Swift BAT trigger 1500148: A solar flare
  45. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  46. GRB 260312B: Fermi GBM Final Real-time Localization
  47. The EP-WXT trigger 01709258843 is not a real source
  48. GRB 260310B: GECAM-B observation of a burst
  49. GRB 260312A: Swift detection of a burst
  50. GRB 260311B: Fermi GBM Final Real-time Localization
  51. GRB 260131A/B: radio detection with the VLA
  52. GRB260307A: GECAM-B observation of a burst
  53. GRB 260308A: SVOM/GRM observation of a short GRB
  54. GRB 260310A: AstroSat CZTI detection of a long burst
  55. GRB 260311A: Fermi GBM Final Real-time Localization
  56. Fermi GRB 260310B: Global MASTER-Net observations report
  57. GRB 260310B: Fermi GBM Final Real-time Localization
  58. Fermi GRB 260310A: Global MASTER-Net observations report
  59. GRB 260307B: SVOM/ECLAIRs refined analysis
  60. GRB 260208A: radio detection with the VLA
  61. GRB 260310A: Fermi GBM Final Real-time Localization
  62. GRB 260307A: Glowbug gamma-ray detection
  63. GRB 260308A: Fermi GBM Final Real-time Localization
  64. Fermi GBM Sub-Threshold Detection of GRB 260307B
  65. GRB 260307B: Mephisto optical upper limits
  66. GRB 260307B: possible NOT optical counterpart
  67. Fermi GRB 260307A: Global MASTER-Net observations report
  68. GRB260307B: GROWTH-India Telescope optical upper limit
  69. GRB 260307B: SVOM/VT optical candidate
  70. GRB 260307B: SVOM/C-GFT upper limit
  71. GRB 260307B: SVOM detection of a burst
  72. GRB 260307A: Fermi GBM Final Localization
  73. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  74. GRB 260207A: TESS Detection and Possible VLA Counterpart
  75. EP260302a: SVOM/VT optical observation
  76. EP260306a: Gemini-North redshift z = 4.773
  77. EP260306a: SVOM/VT optical observation
  78. EP260302a: Gemini-South redshift z = 1.535
  79. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  80. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  81. EP260302a: Optical afterglow rebrightening
  82. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  83. GRB 260303A: 1.3m DFOT optical upper limit
  84. EP260214b: ATCA 6 GHz observations
  85. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  86. GRB 260303A: SVOM/ECLAIRs refined analysis
  87. Fermi GRB 260305A: Global MASTER-Net observations report
  88. GRB 260305A: Fermi GBM Final Real-time Localization
  89. GRB 260303B: AstroSat CZTI detection
  90. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  91. GRB 260303A: SVOM/VT optical observations
  92. GRB 260303A: J-band observations with WINTER
  93. GRB 260303B: NuSTAR detection of prompt emission
  94. EP260302a: Global MASTER-Net observations report
  95. Fermi GRB 260303B: Global MASTER-Net observations report
  96. GRB 260225A: SVOM/ECLAIRs refined analysis
  97. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  98. GRB 260303B: Fermi GBM Final Real-time Localization
  99. EP260302a: analysis of the follow-up EP-FXT observation
  100. EP260302a: LCO observations

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