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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"

26518 results found.

  1. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  2. GRB 260321A: SVOM/VT optical upper limits
  3. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  4. GRB 260320A: Insight-HXMT/HE detection
  5. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  6. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  7. EP260321a: SVOM/VT optical upper limit
  8. GRB 260310A: continued optical observation at Mondy
  9. Fermi GBM Sub-Threshold Detection of GRB 260321A
  10. GRB 260321A: SVOM detection of a burst
  11. EP260321a: Einstein Probe detection of an X-ray transient
  12. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  13. GRB 260318A: Glowbug gamma-ray detection
  14. GRB 260320A: NuSTAR detection of prompt emission
  15. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  16. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  17. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  18. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  19. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  20. GRB 260310A/AT2026fgk: LBT near-infrared observations
  21. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  22. GRB 260318A: SVOM/GRM observation
  23. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  24. GRB 260318A: GECAM-B observation
  25. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  26. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  27. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  28. GRB 260310A / AT 2026fgk: radio detection with the VLA
  29. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  30. GRB 260310A / AT2026fgk: LCO optical observations
  31. GRB 260316B: GECAM-B observation
  32. GRB 260316B: SVOM/GRM observation
  33. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  34. EP260316a: COLIBRÍ faint optical counterpart candidate
  35. GRB 260316B: AstroSat CZTI detection
  36. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP260316a: Xinglong optical upper limit
  38. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  39. GRB 260314A: Glowbug gamma-ray detection
  40. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  41. IceCube-260315A: COLIBRÍ optical observations
  42. EP260314a: Xinglong optical upper limit
  43. EP260314a: optical upper limit with Kinder observations
  44. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  45. GRB 260310A / AT 2026fgk: iTelescope optical observations
  46. EP260314a: COLIBRÍ optical upper limit
  47. GRID detection of GRB 260312B
  48. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  49. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  50. EP260314a: BOOTES-6/DPR optical upper limits at early times
  51. EP260314a: SVOM/VT optical candidate
  52. EP260314a: Einstein Probe detection of an X-ray transient
  53. GRB 260314A: GECAM-B observation of a burst
  54. GRB 260310A / AT2026fgk: SAO RAS optical observations
  55. GRB 260310A / AT2026fgk: TNG NIR detection
  56. GRB 260310A / AT2026fgk: OASDG optical observations
  57. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  58. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  59. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  60. GRB 260313A: A Correction to the Fermi GBM Final Localization
  61. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  62. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  63. GRB 260310B: Insight-HXMT/HE detection
  64. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  65. GRB 260312B: AstroSat CZTI detection
  66. Swift BAT trigger 1500295: A solar flare
  67. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  68. Swift BAT trigger 1500287: A solar flare
  69. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  70. GRB 260308A: Insight-HXMT/HE detection
  71. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  72. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  73. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  74. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  75. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  76. GRB260310A / AT2026fgk: P200 Spectroscopy
  77. GRB 260312B: Glowbug gamma-ray detection
  78. GRB 260310A: Fermi GBM Observation
  79. GRB 260310A: potential optical counterpart
  80. Swift BAT trigger 1500148: A solar flare
  81. GRB 260310B: GECAM-B observation of a burst
  82. GRB 260312A: Swift detection of a burst
  83. GRB 260131A/B: radio detection with the VLA
  84. EP260302a: MeerKAT radio counterpart
  85. GRB260307A: GECAM-B observation of a burst
  86. GRB 260308A: SVOM/GRM observation of a short GRB
  87. GRB 260310A: AstroSat CZTI detection of a long burst
  88. GRB 260307B: SVOM/ECLAIRs refined analysis
  89. GRB 260208A: radio detection with the VLA
  90. GRB 260307A: Glowbug gamma-ray detection
  91. Fermi GBM Sub-Threshold Detection of GRB 260307B
  92. GRB 260307B: Mephisto optical upper limits
  93. GRB 260307B: possible NOT optical counterpart
  94. GRB 260307B: SVOM/VT upper limit with X band data analysis
  95. GRB260307B: GROWTH-India Telescope optical upper limit
  96. GRB 260307B: SVOM/VT optical candidate
  97. GRB 260307B: SVOM/C-GFT upper limit
  98. GRB 260307B: SVOM detection of a burst
  99. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  100. EP260306a: refined analysis of the EP-WXT and EP-FXT observations

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