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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"

21798 results found.

  1. Konus-Wind detection of GRB 260320A
  2. Konus-Wind detection of GRB 260316B
  3. GRB 260321A: SVOM/ECLAIRs refined analysis
  4. EP260329b: J-band upper limits with WINTER
  5. EP260329a: J-band upper limit with WINTER
  6. GRB 260330B: LCO optical upper limits
  7. GRB 260330B: SVOM detection of a burst
  8. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  9. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  10. EP260329a: COLIBRÍ optical upper limit
  11. EP260329a: EP-FXT follow up observation
  12. EP260329a: NOT optical counterpart candidate
  13. EP260329b: Optical follow-up with Kinder observations
  14. EP 260329b: COLIBRÍ optical observations
  15. EP260329a: Optical upper limit with Kinder observations
  16. EP260329b: LCO optical observations of the counterpart
  17. EP260329b: Einstein Probe detection of an X-ray transient
  18. EP260329a: Einstein Probe detection of an X-ray transient
  19. EP-WXT trigger 01709259209: TRT optical counterpart detection
  20. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  21. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  22. EP260327a: SVOM/VT optical upper limits
  23. EP260327a: WINTER J-band upper limit
  24. EP260327a: COLIBRÍ optical upper limits
  25. GRB 260327A: AstroSat CZTI detection of a long burst
  26. EP260327a: Gemini-North optical upper limits
  27. EP260324a: GROWTH-India Telescope optical observation
  28. EP260327a: Einstein Probe detection of an X-ray transient
  29. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  30. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  31. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  32. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  33. EP260321a: JinShan near-infrared observations
  34. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  35. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  36. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  37. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  38. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  39. EP260321a: COLIBRÍ further optical observations and brightening
  40. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  41. EP260214b: ATCA 6 GHz detection
  42. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  43. EP260321a: GOTO detection of blue variable source
  44. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  45. EP260321a: further Kinder optical observations
  46. GRB 260321A: SVOM/VT optical upper limits
  47. EP260321a: Las Cumbres upper limit
  48. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  50. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  51. EP260321a: SVOM/VT optical upper limit
  52. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  53. EP260321a: Einstein Probe detection of an X-ray transient
  54. GRB 260310A / AT 2026fgk: KAIT optical observations
  55. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  56. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  57. GRB 260318A: SVOM/GRM observation
  58. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  59. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  60. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  61. GRB 260310A / AT 2026fgk: radio detection with the VLA
  62. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  63. GRB 260310A / AT2026fgk: LCO optical observations
  64. GRB 260316B: SVOM/GRM observation
  65. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  66. EP260316a: COLIBRÍ faint optical counterpart candidate
  67. GRB 260316B: AstroSat CZTI detection
  68. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  69. EP260316a: Xinglong optical upper limit
  70. EP260316a: optical upper limit with Kinder observations
  71. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  72. IceCube-260315A: COLIBRÍ optical observations
  73. EP260314a: Xinglong optical upper limit
  74. EP260314a: optical upper limit with Kinder observations
  75. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  76. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  77. GRB 260310A / AT 2026fgk: iTelescope optical observations
  78. EP260314a: COLIBRÍ optical upper limit
  79. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  80. EP260314a: SVOM/VT optical candidate
  81. EP260314a: Einstein Probe detection of an X-ray transient
  82. GRB 260310A / AT2026fgk: SAO RAS optical observations
  83. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  84. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  85. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  86. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  87. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  88. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  89. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  90. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  91. GRB 260310A: Fermi GBM Observation
  92. GRB 260310A: potential optical counterpart
  93. GRB 260131A/B: radio detection with the VLA
  94. EP260302a: MeerKAT radio counterpart
  95. GRB 260308A: SVOM/GRM observation of a short GRB
  96. EP260306a: Mondy optical upper limit
  97. GRB 260307B: SVOM/ECLAIRs refined analysis
  98. GRB 260208A: radio detection with the VLA
  99. GRB 260307B: Mephisto optical upper limits
  100. GRB 260307B: possible NOT optical counterpart

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