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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"

12170 results found.

  1. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  2. GRB 260320A: Glowbug gamma-ray detection
  3. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  4. EP260214b: ATCA 6 GHz detection
  5. EP260321a: further Kinder optical observations
  6. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  7. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  8. EP260321a: Einstein Probe detection of an X-ray transient
  9. GRB 260310A / AT 2026fgk: KAIT optical observations
  10. GRB 260320A: NuSTAR detection of prompt emission
  11. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  12. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  13. NOEMA Detection of GRB 260310A / AT 2026fgk
  14. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  15. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  16. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  17. GRB 260317A: Fermi GBM Final Localization
  18. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  19. GRB 260316B: AstroSat CZTI detection
  20. EP260316a: optical upper limit with Kinder observations
  21. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  22. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  23. EP260314a: optical upper limit with Kinder observations
  24. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  25. EP260314a: Global MASTER-Net observations report
  26. Fermi trigger No 795185313: Global MASTER-Net observations report
  27. EP260314a: Einstein Probe detection of an X-ray transient
  28. GRB 260310A/AT2026fgk: radio detection at 15GHz
  29. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  30. Fermi GRB 260314A: Global MASTER-Net observations report
  31. Fermi GRB 260313A: Global MASTER-Net observations report
  32. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  33. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  34. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  35. GRB 260312B: AstroSat CZTI detection
  36. Fermi GRB 260311B: Global MASTER-Net observations report
  37. GRB 260310A: AstroSat CZTI detection of a long burst
  38. Fermi GRB 260310B: Global MASTER-Net observations report
  39. Fermi GRB 260310A: Global MASTER-Net observations report
  40. GRB 260308A: Fermi GBM Final Real-time Localization
  41. Fermi GRB 260307A: Global MASTER-Net observations report
  42. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  43. EP260306a: Einstein Probe detection of an X-ray transient
  44. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  45. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  46. Fermi GRB 260305A: Global MASTER-Net observations report
  47. GRB 260303B: AstroSat CZTI detection
  48. GRB 260304A: AstroSat CZTI detection of a long burst
  49. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  50. GRB 260303B: NuSTAR detection of prompt emission
  51. GRB 260228A: SVOM/ECLAIRs refined analysis
  52. GRB 260225A: SVOM/ECLAIRs refined analysis
  53. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  54. GRB 260303B: Fermi GBM Final Real-time Localization
  55. EP260302a: analysis of the follow-up EP-FXT observation
  56. EP260302a: LCO observations
  57. EP260302a: BOOTES-7 optical counterpart detection at early times
  58. GRB 260303A: SVOM detection of a burst
  59. EP260302a: Einstein Probe detection of an X-ray transient
  60. EP260227a: Mondy optical observations
  61. EP260227a: Mephisto optical detection
  62. EP260227a: SVOM/VT optical observation
  63. GRB 260228A: SVOM detection of a burst
  64. EP260227a: NOT optical observations
  65. EP260227a: Global MASTER-Net observations report
  66. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  67. Konus-Wind detection of GRB 260226A
  68. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  69. GRB 260226A: COLIBRÍ optical upper limits
  70. GRB 260226A: NuSTAR detection of bright prompt emission
  71. GRB 260226A: Fermi-LAT refined analysis
  72. The EP-WXT trigger 01709258652 is likely a flaring star
  73. LAT GRB260226.44: Global MASTER-Net observations report
  74. GRB 260226A: AstroSat CZTI detection of bright long burst
  75. GRB 260226A: Fermi-LAT detection of a bright burst
  76. EP260223a: Xinglong optical upper limit
  77. sb26021801: SVOM/C-GFT upper limit
  78. EP260223a: Einstein Probe detection of an X-ray transient
  79. EP260221a: Optical upper limit with Kinder observations
  80. Fermi GRB 260223A: Global MASTER-Net observations report
  81. EP260221a: COLIBRÍ optical counterpart candidate
  82. EP260221a: Gemini South z-band upper limit
  83. EP260221a: EP-FXT follow-up observation
  84. EP260221a: Xinglong optical upper limit
  85. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  86. EP260221a: Einstein Probe detection of an X-ray transient
  87. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  88. sb26021801: SVOM detection of a long faint X-ray transient
  89. EP260210a: Mondy optical upper limits
  90. Konus-Wind detection of GRB 260212A
  91. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  92. EP260214b: Optical upper limit with Kinder observations
  93. EP260214a: Optical upper limits with Kinder observations
  94. EP260214b: EP-FXT follow-up observation
  95. EP260214a: COLIBRÍ optical upper limits
  96. EP260214a: refined analysis of the EP-FXT observation
  97. EP260214b: Einstein Probe detection of a fast X-ray transient
  98. EP260214a: Einstein Probe detection of an X-ray transient
  99. GRB 260212A: AstroSat CZTI detection
  100. EP260213a: Optical upper limits with Kinder observations

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