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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"

20395 results found.

  1. EP260321a :Xinglong optical observations
  2. EP260327a: Xinglong optical upper limit
  3. GRB 260330B: SVOM/VT optical upper limits
  4. GRB 260321A: SVOM/ECLAIRs refined analysis
  5. EP260329b: J-band upper limits with WINTER
  6. EP260329a: J-band upper limit with WINTER
  7. GRB 260310A: VLA Multi-frequency Radio Observations
  8. GRB 260330B: LCO optical upper limits
  9. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  10. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  11. EP260329a: COLIBRÍ optical upper limit
  12. EP260329a: EP-FXT follow up observation
  13. EP260329a: NOT optical counterpart candidate
  14. EP260329b: Optical follow-up with Kinder observations
  15. EP 260329b: COLIBRÍ optical observations
  16. EP260329a: Optical upper limit with Kinder observations
  17. EP260329b: LCO optical observations of the counterpart
  18. EP260329b: Einstein Probe detection of an X-ray transient
  19. EP260329a: Einstein Probe detection of an X-ray transient
  20. EP-WXT trigger 01709259209: TRT optical counterpart detection
  21. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  22. GRID detection of GRB 260326A
  23. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  24. EP260327a: SVOM/VT optical upper limits
  25. EP260327a: WINTER J-band upper limit
  26. EP260327a: COLIBRÍ optical upper limits
  27. GRB 260327A: AstroSat CZTI detection of a long burst
  28. EP260327a: Gemini-North optical upper limits
  29. EP260324a: GROWTH-India Telescope optical observation
  30. EP260327a: Einstein Probe detection of an X-ray transient
  31. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  32. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  33. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  34. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  35. EP260321a: JinShan near-infrared observations
  36. EP260321a: Upper limits from a neutrino search with IceCube
  37. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  38. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  39. GRID detection of GRB 260320A
  40. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  41. EP260321a: COLIBRÍ further optical observations and brightening
  42. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  43. EP260214b: ATCA 6 GHz detection
  44. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  45. The EP-WXT trigger 01709259045 is likely a flaring star
  46. EP260321a: GOTO detection of blue variable source
  47. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  48. EP260321a: further Kinder optical observations
  49. GRB 260321A: SVOM/VT optical upper limits
  50. EP260321a: Las Cumbres upper limit
  51. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  53. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  54. EP260321a: SVOM/VT optical upper limit
  55. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  56. EP260321a: Einstein Probe detection of an X-ray transient
  57. GRB 260310A / AT 2026fgk: KAIT optical observations
  58. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  59. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  60. GRB 260318A: SVOM/GRM observation
  61. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  62. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  63. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  64. GRB 260310A / AT 2026fgk: radio detection with the VLA
  65. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  66. GRB 260310A / AT2026fgk: LCO optical observations
  67. GRB 260316B: SVOM/GRM observation
  68. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  69. EP260316a: COLIBRÍ faint optical counterpart candidate
  70. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  71. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  72. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  73. EP260316a: Xinglong optical upper limit
  74. EP260316a: optical upper limit with Kinder observations
  75. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  76. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  77. IceCube-260315A: COLIBRÍ optical observations
  78. EP260314a: Xinglong optical upper limit
  79. EP260314a: optical upper limit with Kinder observations
  80. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  81. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  82. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  83. GRB 260310A / AT 2026fgk: iTelescope optical observations
  84. EP260314a: COLIBRÍ optical upper limit
  85. GRID detection of GRB 260312B
  86. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  87. EP260314a: SVOM/VT optical candidate
  88. EP260314a: Einstein Probe detection of an X-ray transient
  89. GRB 260310A / AT2026fgk: SAO RAS optical observations
  90. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  91. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  92. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  93. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  94. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  95. GRB 260312B: AstroSat CZTI detection
  96. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  97. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  98. GRB 260310A: potential optical counterpart
  99. Fermi GRB 260311B: Global MASTER-Net observations report
  100. GRB 260131A/B: radio detection with the VLA

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