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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

19540 results found.

  1. EP260605a: Einstein Probe detection of a fast X-ray transient
  2. EP260603a: COLIBRÍ optical upper limit
  3. GRB 260604C: LCO optical upper limit
  4. EP260602d: EP-FXT follow-up observation
  5. EP260602c: EP-FXT follow-up observation
  6. GRB 260601B / EP260601a: AstroSat CZTI detection
  7. GRB 260527A/EP260527a: 6 GHz VLA observations
  8. GRB 260604C: Kilonova-Catcher optical afterglow detection
  9. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  10. GRB 260604C: Jinshan optical observations
  11. EP260602d: J-band upper limit with WINTER
  12. EP260602b: J-band upper limit with WINTER
  13. GRB 260604C: LAST detection of optical counterpart candidate
  14. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  15. EP260602a: EP-FXT follow-up observation
  16. EP260603a: Einstein Probe detection of a fast X-ray transient
  17. EP260602d: Optical Upper limits with kinder observations
  18. EP260602b: Liverpool Telescope observations
  19. EP260602a: Liverpool Telescope optical upper limits
  20. EP260602b: Liverpool Telescope and LCO observations
  21. EP260602a: GTC and Liverpool Telescope optical observations
  22. Konus-Wind detection of GRB 260601B/EP260601a
  23. GRB 260601B / EP260601a: Mondy optical upper limit
  24. EP260602b: EP-FXT follow-up observation
  25. GRB 260603A: Kilonova-Catcher optical upper limit
  26. GRB 260603A: SVOM/VT optical observations
  27. EP260602a: NOT NIR J-band observations
  28. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  29. EP260602d: Einstein Probe detection of a fast X-ray transient
  30. GRB 260601A: SVOM/GRM observation of a short burst
  31. EP260602c: Einstein Probe detection of a fast X-ray transient
  32. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  33. EP260602a: COLIBRÍ optical observations
  34. GRB260601B/EP260601a: NOT near-infrared observations
  35. EP260602b: Einstein Probe detection of a fast X-ray transient
  36. EP260602a: SVOM/VT optical candidate
  37. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  38. GRB 260601B/EP260601a: J-band upper limit with WINTER
  39. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  40. EP260530a/AT 2026nwl: KAIT optical observations
  41. EP260602a: Optical upper limits with Kinder observations
  42. EP260602a: Einstein Probe detection of a fast X-ray transient
  43. GRB 260601B/EP260601a: SVOM/VT optical observations
  44. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  45. EP260601a: Einstein Probe detection of an X-ray transient
  46. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  47. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  48. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  49. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  50. AT2026nik: EP-FXT X-ray counterpart
  51. AT 2026nuz: COLIBRÍ optical observations
  52. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  53. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  54. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  55. EP260526a: SVOM/VT optical upper limits
  56. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  57. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  58. EP260527a/GRB 260527A: EP-FXT follow-up observation
  59. EP260527a: SVOM/VT optical observation
  60. EP260527a: COLIBRÍ optical detection
  61. EP260527a: Einstein Probe detection of a fast X-ray transient
  62. EP260526a: LCO optical upper limits
  63. EP260526a: Einstein Probe detection of a fast X-ray transient
  64. GRB 260525A: AstroSat CZTI detection
  65. EP260526.405: COLIBRÍ optical upper limits
  66. The EP-WXT trigger 01709266106 is not a real source
  67. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  68. EP-WXT 01709266106: NOT optical upper limits
  69. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  70. GRB 260511A: iTelescope T-75 optical detection
  71. GRB 260520B: SVOM/GRM observation
  72. Konus-Wind detection of GRB 260519C
  73. GRB 260509A: SVOM/ECLAIRs refined analysis
  74. GRB 260421B: radio detection with the VLA
  75. GRB 260509A: CrAO ZTSh optical upper limit
  76. GRB 260516D: GOTO optical counterpart detection
  77. GRB 260516D: LCO optical observations
  78. GRB 260515A: further Liverpool Telescope observations
  79. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  80. GRB 260516D: GROWTH-India Telescope optical detection
  81. GRB 260516D: SVOM/VT optical bright candidate
  82. GRB 260515A: CrAO ZTSh BVRI optical observations
  83. Konus-Wind detection of GRB 260515A
  84. GRB 260515A: LCO optical counterpart detection
  85. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  86. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  87. EP260514a: NOT optical counterpart confirmation
  88. EP260514a: TRT optical counterpart candidate
  89. EP260514a: SVOM/VT optical candidate
  90. GRB 260515A: OHP/T193 optical observations
  91. EP260514a: COLIBRÍ optical upper limits
  92. GRB 260515A: LCO optical observations
  93. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  94. GRB 260515A: SVOM/VT optical candidate from VHF data
  95. GRB 260515A: JinShan optical counterpart candidate
  96. GRB 260515A: SVOM detection of a burst
  97. EP260514a: GROWTH-India Telescope optical upper limit
  98. GRB 260511B: GMG Optical Upper Limit
  99. EP260514a: Einstein Probe detection of a fast X-ray transient
  100. EP260512a: LCO optical upper limits

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