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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"

26513 results found.

  1. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  2. EP260321a: SVOM/VT optical upper limit
  3. GRB 260310A: continued optical observation at Mondy
  4. Fermi GBM Sub-Threshold Detection of GRB 260321A
  5. GRB 260321A: SVOM detection of a burst
  6. EP260321a: Einstein Probe detection of an X-ray transient
  7. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  8. GRB 260318A: Glowbug gamma-ray detection
  9. GRB 260320A: NuSTAR detection of prompt emission
  10. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  11. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  12. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  13. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  14. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  15. GRB 260310A/AT2026fgk: LBT near-infrared observations
  16. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  17. GRB 260318A: SVOM/GRM observation
  18. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  19. GRB 260318A: GECAM-B observation
  20. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  21. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  22. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  23. GRB 260310A / AT 2026fgk: radio detection with the VLA
  24. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  25. GRB 260310A / AT2026fgk: LCO optical observations
  26. GRB 260316B: GECAM-B observation
  27. GRB 260316B: SVOM/GRM observation
  28. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  29. EP260316a: COLIBRÍ faint optical counterpart candidate
  30. GRB 260316B: AstroSat CZTI detection
  31. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  32. EP260316a: Xinglong optical upper limit
  33. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  34. GRB 260314A: Glowbug gamma-ray detection
  35. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  36. IceCube-260315A: COLIBRÍ optical observations
  37. EP260314a: Xinglong optical upper limit
  38. EP260314a: optical upper limit with Kinder observations
  39. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  40. GRB 260310A / AT 2026fgk: iTelescope optical observations
  41. EP260314a: COLIBRÍ optical upper limit
  42. GRID detection of GRB 260312B
  43. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  44. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP260314a: BOOTES-6/DPR optical upper limits at early times
  46. EP260314a: SVOM/VT optical candidate
  47. EP260314a: Einstein Probe detection of an X-ray transient
  48. GRB 260314A: GECAM-B observation of a burst
  49. GRB 260310A / AT2026fgk: SAO RAS optical observations
  50. GRB 260310A / AT2026fgk: TNG NIR detection
  51. GRB 260310A / AT2026fgk: OASDG optical observations
  52. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  53. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  54. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  55. GRB 260313A: A Correction to the Fermi GBM Final Localization
  56. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  57. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  58. GRB 260310B: Insight-HXMT/HE detection
  59. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  60. GRB 260312B: AstroSat CZTI detection
  61. Swift BAT trigger 1500295: A solar flare
  62. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  63. Swift BAT trigger 1500287: A solar flare
  64. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  65. GRB 260308A: Insight-HXMT/HE detection
  66. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  68. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  69. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  70. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  71. GRB260310A / AT2026fgk: P200 Spectroscopy
  72. GRB 260312B: Glowbug gamma-ray detection
  73. GRB 260310A: Fermi GBM Observation
  74. GRB 260310A: potential optical counterpart
  75. Swift BAT trigger 1500148: A solar flare
  76. GRB 260310B: GECAM-B observation of a burst
  77. GRB 260312A: Swift detection of a burst
  78. GRB 260131A/B: radio detection with the VLA
  79. EP260302a: MeerKAT radio counterpart
  80. GRB260307A: GECAM-B observation of a burst
  81. GRB 260308A: SVOM/GRM observation of a short GRB
  82. GRB 260310A: AstroSat CZTI detection of a long burst
  83. GRB 260307B: SVOM/ECLAIRs refined analysis
  84. GRB 260208A: radio detection with the VLA
  85. GRB 260307A: Glowbug gamma-ray detection
  86. Fermi GBM Sub-Threshold Detection of GRB 260307B
  87. GRB 260307B: Mephisto optical upper limits
  88. GRB 260307B: possible NOT optical counterpart
  89. GRB 260307B: SVOM/VT upper limit with X band data analysis
  90. GRB260307B: GROWTH-India Telescope optical upper limit
  91. GRB 260307B: SVOM/VT optical candidate
  92. GRB 260307B: SVOM/C-GFT upper limit
  93. GRB 260307B: SVOM detection of a burst
  94. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  95. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  96. GRB 260207A: TESS Detection and Possible VLA Counterpart
  97. EP260302a: SVOM/VT optical observation
  98. EP260306a: Gemini-North redshift z = 4.773
  99. EP260306a: SVOM/VT optical observation
  100. EP260306a: COLIBRÍ optical observations of the fading and red counterpart

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