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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"

32687 results found.

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

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