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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"

21769 results found.

  1. GRB 260610B: SVOM/GRM observation
  2. GRB 260614B: SVOM/VT optical candidate from VHF data
  3. GRB 260614B: SVOM detection of a burst
  4. GRB 260611B: SVOM/GRM detection
  5. GRB 260603C: AstroSat CZTI detection
  6. GRB 260610B: further Liverpool Telescope optical observations
  7. GRB 260610B / AT2026owq: GRANDMA optical observations
  8. GRB 260610B / AT2026owq: further SAO RAS optical observations
  9. EP260605a: COLIBRÍ optical upper limits
  10. GRB 260610b: Liverpool Telescope optical observations
  11. EP260610b: Liverpool Telescope optical upper limits
  12. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  13. GRB 260610B / AT2026owq: SAO RAS optical observations
  14. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  15. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  16. GRB 260610B / AT2026owq: Early ATLAS observations
  17. GRB 260610B: TRT optical observation
  18. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  19. EP260610b: COLIBRÍ optical observations
  20. GRB 260610B: DDOTI optical observations
  21. EP260610b: MAO/AZT-22 optical observations
  22. GRB 260610B: GOTO optical counterpart candidate
  23. EP260610b: NOT optical observation
  24. EP260610b: SVOM/VT optical confirmation with blue color
  25. GRB 260515A: SOAR optical observations
  26. EP260610a: SVOM/VT optical upper limits
  27. EP260610b: Einstein Probe detection of an X-ray transient
  28. Konus-Wind detection of GRB 260601A
  29. EP260610a: COLIBRÍ optical upper limits
  30. EP260610a: Einstein Probe detection of a fast X-ray transient
  31. Konus-Wind detection of GRB 260604C
  32. GRB 260604C: SVOM/ECLAIRs refined analysis
  33. GRB 260608A: SVOM/ECLAIRs refined analysis
  34. Konus-Wind detection of GRB 260607B
  35. GRB 260604C: further SAO RAS optical observations
  36. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  37. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  38. GRB 260604C: SVOM/C-GFT upper limit
  39. GRB 260607B: AstroSat CZTI detection
  40. EP260605a: EP-FXT follow-up observation
  41. GRB 260607A: TRT optical observations
  42. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  43. GRB 260604A: SVOM/GRM detection
  44. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  45. GRB 260607B: Fermi-LAT detection
  46. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  47. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  48. GRB 260604C: 6 GHz VLA observations
  49. GRB 260604C: SAO RAS optical observations
  50. GRB 260604B: SVOM/GRM detection
  51. GRB260603A: SVOM/ECLAIRs refined analysis
  52. EP260605a: Einstein Probe detection of a fast X-ray transient
  53. EP260603a: COLIBRÍ optical upper limit
  54. GRB 260604C: LCO optical upper limit
  55. GRB 260604C: Liverpool Telescope optical detection
  56. EP260602d: EP-FXT follow-up observation
  57. EP260602c: EP-FXT follow-up observation
  58. GRB 260527A/EP260527a: 6 GHz VLA observations
  59. GRB 260604C: Kilonova-Catcher optical afterglow detection
  60. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  61. GRB 260604C: Jinshan optical observations
  62. EP260602d: J-band upper limit with WINTER
  63. EP260602b: J-band upper limit with WINTER
  64. GRB 260604C: LAST detection of optical counterpart candidate
  65. GRB 260604C: SVOM detection of a long burst
  66. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  67. EP260602a: EP-FXT follow-up observation
  68. EP260603a: Einstein Probe detection of a fast X-ray transient
  69. EP260602d: Optical Upper limits with kinder observations
  70. EP260602b: Liverpool Telescope observations
  71. EP260602a: Liverpool Telescope optical upper limits
  72. EP260602b: Liverpool Telescope and LCO observations
  73. EP260602a: GTC and Liverpool Telescope optical observations
  74. Konus-Wind detection of GRB 260601B/EP260601a
  75. GRB 260601B / EP260601a: Mondy optical upper limit
  76. EP260602b: EP-FXT follow-up observation
  77. GRB 260603A: Kilonova-Catcher optical upper limit
  78. GRB 260603A: SVOM/VT optical observations
  79. EP260602a: NOT NIR J-band observations
  80. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  81. EP260602d: Einstein Probe detection of a fast X-ray transient
  82. GRB 260601A: SVOM/GRM observation of a short burst
  83. EP260602c: Einstein Probe detection of a fast X-ray transient
  84. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  85. EP260602a: COLIBRÍ optical observations
  86. GRB260601B/EP260601a: NOT near-infrared observations
  87. GRB 260603A: SVOM detection of a burst
  88. EP260602b: Einstein Probe detection of a fast X-ray transient
  89. EP260602a: SVOM/VT optical candidate
  90. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  91. GRB 260601B/EP260601a: J-band upper limit with WINTER
  92. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  93. EP260530a/AT 2026nwl: KAIT optical observations
  94. EP260602a: Optical upper limits with Kinder observations
  95. EP260602a: Einstein Probe detection of a fast X-ray transient
  96. GRB 260601B/EP260601a: SVOM/VT optical observations
  97. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  98. EP260601a: Einstein Probe detection of an X-ray transient
  99. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  100. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection

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