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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"

32688 results found.

  1. Fermi GRB 260318A: Global MASTER-Net observations report
  2. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  3. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  4. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  5. GRB 260310A / AT 2026fgk: radio detection with the VLA
  6. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  7. GRB 260310A / AT2026fgk: LCO optical observations
  8. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  9. GRB 260316B: GECAM-B observation
  10. GRB 260316B: SVOM/GRM observation
  11. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  12. EP260316a: COLIBRÍ faint optical counterpart candidate
  13. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  14. GRB 260316B: AstroSat CZTI detection
  15. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  16. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  17. EP260316a: Xinglong optical upper limit
  18. EP260316a: optical upper limit with Kinder observations
  19. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  20. GRB 260314A: Glowbug gamma-ray detection
  21. IceCube-260315A: COLIBRÍ optical observations
  22. EP260314a: Xinglong optical upper limit
  23. EP260314a: optical upper limit with Kinder observations
  24. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  25. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  26. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  27. GRB 260310A / AT 2026fgk: iTelescope optical observations
  28. EP260314a: COLIBRÍ optical upper limit
  29. GRID detection of GRB 260312B
  30. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  31. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  32. EP260314a: Global MASTER-Net observations report
  33. EP260314a: SVOM/VT optical candidate
  34. GRB 260314A: GECAM-B observation of a burst
  35. GRB 260310A / AT2026fgk: SAO RAS optical observations
  36. GRB 260310A/AT2026fgk: radio detection at 15GHz
  37. GRB 260310A / AT2026fgk: TNG NIR detection
  38. GRB 260310A / AT2026fgk: OASDG optical observations
  39. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  40. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  41. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  42. Fermi GRB 260314A: Global MASTER-Net observations report
  43. Fermi GRB 260313A: Global MASTER-Net observations report
  44. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  45. GRB 260313A: A Correction to the Fermi GBM Final Localization
  46. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  47. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  48. GRB 260310B: Insight-HXMT/HE detection
  49. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  50. GRB 260310A: NOT optical polarimetry
  51. GRB 260312B: AstroSat CZTI detection
  52. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  53. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  54. GRB 260308A: Insight-HXMT/HE detection
  55. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  56. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  57. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  58. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  59. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  60. GRB260310A / AT2026fgk: P200 Spectroscopy
  61. GRB 260312B: Glowbug gamma-ray detection
  62. GRB 260310A: Fermi GBM Observation
  63. GRB 260310A: potential optical counterpart
  64. Fermi GRB 260312B: Global MASTER-Net observations report
  65. Fermi GRB 260311B: Global MASTER-Net observations report
  66. GRB 260310B: GECAM-B observation of a burst
  67. Retraction of GCN 43965: GRB is actually solar flare
  68. GRB 260131A/B: radio detection with the VLA
  69. EP260302a: MeerKAT radio counterpart
  70. GRB260307A: GECAM-B observation of a burst
  71. GRB 260308A: SVOM/GRM observation of a short GRB
  72. EP260306a: Mondy optical upper limit
  73. GRB 260310A: AstroSat CZTI detection of a long burst
  74. Fermi GRB 260310B: Global MASTER-Net observations report
  75. Fermi GRB 260310A: Global MASTER-Net observations report
  76. GRB 260307B: SVOM/ECLAIRs refined analysis
  77. GRB 260208A: radio detection with the VLA
  78. GRB 260307A: Glowbug gamma-ray detection
  79. Fermi GBM Sub-Threshold Detection of GRB 260307B
  80. GRB 260307B: Mephisto optical upper limits
  81. GRB 260307B: possible NOT optical counterpart
  82. GRB 260307B: SVOM/VT upper limit with X band data analysis
  83. Fermi GRB 260307A: Global MASTER-Net observations report
  84. GRB260307B: GROWTH-India Telescope optical upper limit
  85. GRB 260307B: SVOM/VT optical candidate
  86. GRB 260307B: SVOM/C-GFT upper limit
  87. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  88. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  89. GRB 260207A: TESS Detection and Possible VLA Counterpart
  90. EP260302a: SVOM/VT optical observation
  91. EP260306a: Gemini-North redshift z = 4.773
  92. EP260306a: SVOM/VT optical observation
  93. EP260302a: Gemini-South redshift z = 1.535
  94. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  95. EP260306a: Einstein Probe detection of an X-ray transient
  96. EP260302a: Optical afterglow rebrightening
  97. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  98. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  99. GRB 260303A: 1.3m DFOT optical upper limit
  100. EP260214b: ATCA 6 GHz observations

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