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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"

19305 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  2. GRB 260310A / AT2026fgk: SAO RAS optical observations
  3. GRB 260310A/AT2026fgk: radio detection at 15GHz
  4. GRB 260310A / AT2026fgk: TNG NIR detection
  5. GRB 260310A / AT2026fgk: OASDG optical observations
  6. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  7. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  8. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  9. Fermi GRB 260314A: Global MASTER-Net observations report
  10. Fermi GRB 260313A: Global MASTER-Net observations report
  11. GRB 260314A: Fermi GBM Final Real-time Localization
  12. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  13. GRB 260313A: A Correction to the Fermi GBM Final Localization
  14. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  15. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  16. GRB 260310B: Insight-HXMT/HE detection
  17. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  18. GRB 260310A: NOT optical polarimetry
  19. GRB 260312B: AstroSat CZTI detection
  20. GRB 260313A: Fermi GBM Final Real-time Localization
  21. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  22. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  23. GRB 260308A: Insight-HXMT/HE detection
  24. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  25. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  26. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  27. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  28. GRB260310A / AT2026fgk: P200 Spectroscopy
  29. GRB 260312B: Glowbug gamma-ray detection
  30. GRB 260310A: Fermi GBM Observation
  31. GRB 260310A: potential optical counterpart
  32. Fermi GRB 260312B: Global MASTER-Net observations report
  33. Fermi GRB 260311B: Global MASTER-Net observations report
  34. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  35. GRB 260312B: Fermi GBM Final Real-time Localization
  36. The EP-WXT trigger 01709258843 is not a real source
  37. GRB 260310B: GECAM-B observation of a burst
  38. GRB 260311B: Fermi GBM Final Real-time Localization
  39. GRB 260131A/B: radio detection with the VLA
  40. EP260302a: MeerKAT radio counterpart
  41. GRB260307A: GECAM-B observation of a burst
  42. GRB 260308A: SVOM/GRM observation of a short GRB
  43. EP260306a: Mondy optical upper limit
  44. GRB 260310A: AstroSat CZTI detection of a long burst
  45. GRB 260311A: Fermi GBM Final Real-time Localization
  46. Fermi GRB 260310B: Global MASTER-Net observations report
  47. GRB 260310B: Fermi GBM Final Real-time Localization
  48. Fermi GRB 260310A: Global MASTER-Net observations report
  49. GRB 260307B: SVOM/ECLAIRs refined analysis
  50. GRB 260208A: radio detection with the VLA
  51. GRB 260310A: Fermi GBM Final Real-time Localization
  52. GRB 260307A: Glowbug gamma-ray detection
  53. GRB 260308A: Fermi GBM Final Real-time Localization
  54. Fermi GBM Sub-Threshold Detection of GRB 260307B
  55. GRB 260307B: Mephisto optical upper limits
  56. GRB 260307B: possible NOT optical counterpart
  57. GRB 260307B: SVOM/VT upper limit with X band data analysis
  58. Fermi GRB 260307A: Global MASTER-Net observations report
  59. GRB260307B: GROWTH-India Telescope optical upper limit
  60. GRB 260307B: SVOM/VT optical candidate
  61. GRB 260307B: SVOM/C-GFT upper limit
  62. GRB 260307B: SVOM detection of a burst
  63. GRB 260307A: Fermi GBM Final Localization
  64. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  65. GRB 260207A: TESS Detection and Possible VLA Counterpart
  66. EP260302a: SVOM/VT optical observation
  67. EP260306a: Gemini-North redshift z = 4.773
  68. EP260306a: SVOM/VT optical observation
  69. EP260302a: Gemini-South redshift z = 1.535
  70. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  71. EP260306a: Einstein Probe detection of an X-ray transient
  72. EP260302a: Optical afterglow rebrightening
  73. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  74. GRB 260303A: 1.3m DFOT optical upper limit
  75. EP260214b: ATCA 6 GHz observations
  76. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  77. GRB 260303A: SVOM/ECLAIRs refined analysis
  78. Fermi GRB 260305A: Global MASTER-Net observations report
  79. GRB 260305A: Fermi GBM Final Real-time Localization
  80. GRB 260303B: AstroSat CZTI detection
  81. GRB 260304A: AstroSat CZTI detection of a long burst
  82. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  83. GRB 260303A: SVOM/VT optical observations
  84. GRB 260303A: J-band observations with WINTER
  85. GRB 260303B: NuSTAR detection of prompt emission
  86. EP260302a: Global MASTER-Net observations report
  87. Fermi GRB 260303B: Global MASTER-Net observations report
  88. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  89. GRB 260228A: SVOM/ECLAIRs refined analysis
  90. GRB 260225A: SVOM/ECLAIRs refined analysis
  91. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  92. GRB 260303B: Fermi GBM Final Real-time Localization
  93. EP260302a: analysis of the follow-up EP-FXT observation
  94. EP260227a: Gemini-South optical observations
  95. EP260302a: LCO observations
  96. EP260302a: BOOTES-7 optical counterpart detection at early times
  97. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  98. GRB 260303A: SVOM detection of a burst
  99. GRB 260228A: EP-FXT follow-up observation
  100. EP260302a: Einstein Probe detection of an X-ray transient

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