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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"

32573 results found.

  1. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  2. EP260316a: Xinglong optical upper limit
  3. EP260316a: optical upper limit with Kinder observations
  4. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  5. GRB 260314A: Glowbug gamma-ray detection
  6. IceCube-260315A: COLIBRÍ optical observations
  7. EP260314a: Xinglong optical upper limit
  8. EP260314a: optical upper limit with Kinder observations
  9. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  10. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  11. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  12. GRB 260310A / AT 2026fgk: iTelescope optical observations
  13. EP260314a: COLIBRÍ optical upper limit
  14. GRID detection of GRB 260312B
  15. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  16. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  17. EP260314a: Global MASTER-Net observations report
  18. EP260314a: SVOM/VT optical candidate
  19. GRB 260314A: GECAM-B observation of a burst
  20. GRB 260310A / AT2026fgk: SAO RAS optical observations
  21. GRB 260310A/AT2026fgk: radio detection at 15GHz
  22. GRB 260310A / AT2026fgk: TNG NIR detection
  23. GRB 260310A / AT2026fgk: OASDG optical observations
  24. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  25. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  26. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  27. Fermi GRB 260314A: Global MASTER-Net observations report
  28. Fermi GRB 260313A: Global MASTER-Net observations report
  29. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  30. GRB 260313A: A Correction to the Fermi GBM Final Localization
  31. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  32. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  33. GRB 260310B: Insight-HXMT/HE detection
  34. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  35. GRB 260310A: NOT optical polarimetry
  36. GRB 260312B: AstroSat CZTI detection
  37. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  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. GRB 260310B: GECAM-B observation of a burst
  52. Retraction of GCN 43965: GRB is actually solar flare
  53. GRB 260131A/B: radio detection with the VLA
  54. EP260302a: MeerKAT radio counterpart
  55. GRB260307A: GECAM-B observation of a burst
  56. GRB 260308A: SVOM/GRM observation of a short GRB
  57. EP260306a: Mondy optical upper limit
  58. GRB 260310A: AstroSat CZTI detection of a long burst
  59. Fermi GRB 260310B: Global MASTER-Net observations report
  60. Fermi GRB 260310A: Global MASTER-Net observations report
  61. GRB 260307B: SVOM/ECLAIRs refined analysis
  62. GRB 260208A: radio detection with the VLA
  63. GRB 260307A: Glowbug gamma-ray detection
  64. Fermi GBM Sub-Threshold Detection of GRB 260307B
  65. GRB 260307B: Mephisto optical upper limits
  66. GRB 260307B: possible NOT optical counterpart
  67. GRB 260307B: SVOM/VT upper limit with X band data analysis
  68. Fermi GRB 260307A: Global MASTER-Net observations report
  69. GRB260307B: GROWTH-India Telescope optical upper limit
  70. GRB 260307B: SVOM/VT optical candidate
  71. GRB 260307B: SVOM/C-GFT upper limit
  72. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  73. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  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. EP260306a: Einstein Probe detection of an X-ray transient
  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 (duplicate submission)
  84. GRB 260303A: 1.3m DFOT optical upper limit
  85. EP260214b: ATCA 6 GHz observations
  86. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  87. GRB 260303A: SVOM/ECLAIRs refined analysis
  88. Fermi GRB 260305A: Global MASTER-Net observations report
  89. GRB 260303B: AstroSat CZTI detection
  90. GRB 260303A: SVOM/VT optical observations
  91. GRB 260303A: J-band observations with WINTER
  92. GRB 260303B: NuSTAR detection of prompt emission
  93. EP260302a: Global MASTER-Net observations report
  94. Fermi GRB 260303B: Global MASTER-Net observations report
  95. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  96. GRB 260228A: SVOM/ECLAIRs refined analysis
  97. GRB 260225A: SVOM/ECLAIRs refined analysis
  98. EP260302a: analysis of the follow-up EP-FXT observation
  99. EP260227a: Gemini-South optical observations
  100. EP260302a: LCO observations

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