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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21765 results found.

  1. GRB 260603C: AstroSat CZTI detection
  2. GRB 260610B: further Liverpool Telescope optical observations
  3. GRB 260610B / AT2026owq: GRANDMA optical observations
  4. GRB 260610B / AT2026owq: further SAO RAS optical observations
  5. EP260605a: COLIBRÍ optical upper limits
  6. GRB 260610b: Liverpool Telescope optical observations
  7. EP260610b: Liverpool Telescope optical upper limits
  8. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  9. GRB 260610B / AT2026owq: SAO RAS optical observations
  10. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  11. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  12. GRB 260610B / AT2026owq: Early ATLAS observations
  13. GRB 260610B: TRT optical observation
  14. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  15. EP260610b: COLIBRÍ optical observations
  16. GRB 260610B: DDOTI optical observations
  17. EP260610b: MAO/AZT-22 optical observations
  18. GRB 260610B: GOTO optical counterpart candidate
  19. EP260610b: NOT optical observation
  20. EP260610b: SVOM/VT optical confirmation with blue color
  21. GRB 260515A: SOAR optical observations
  22. EP260610a: SVOM/VT optical upper limits
  23. EP260610b: Einstein Probe detection of an X-ray transient
  24. Konus-Wind detection of GRB 260601A
  25. EP260610a: COLIBRÍ optical upper limits
  26. EP260610a: Einstein Probe detection of a fast X-ray transient
  27. Konus-Wind detection of GRB 260604C
  28. GRB 260604C: SVOM/ECLAIRs refined analysis
  29. GRB 260608A: SVOM/ECLAIRs refined analysis
  30. Konus-Wind detection of GRB 260607B
  31. GRB 260604C: further SAO RAS optical observations
  32. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  33. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  34. GRB 260604C: SVOM/C-GFT upper limit
  35. GRB 260607B: AstroSat CZTI detection
  36. EP260605a: EP-FXT follow-up observation
  37. GRB 260607A: TRT optical observations
  38. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  39. GRB 260604A: SVOM/GRM detection
  40. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  41. GRB 260607B: Fermi-LAT detection
  42. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  43. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  44. GRB 260604C: 6 GHz VLA observations
  45. GRB 260604C: SAO RAS optical observations
  46. GRB 260604B: SVOM/GRM detection
  47. GRB260603A: SVOM/ECLAIRs refined analysis
  48. EP260605a: Einstein Probe detection of a fast X-ray transient
  49. EP260603a: COLIBRÍ optical upper limit
  50. GRB 260604C: LCO optical upper limit
  51. GRB 260604C: Liverpool Telescope optical detection
  52. EP260602d: EP-FXT follow-up observation
  53. EP260602c: EP-FXT follow-up observation
  54. GRB 260527A/EP260527a: 6 GHz VLA observations
  55. GRB 260604C: Kilonova-Catcher optical afterglow detection
  56. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  57. GRB 260604C: Jinshan optical observations
  58. EP260602d: J-band upper limit with WINTER
  59. EP260602b: J-band upper limit with WINTER
  60. GRB 260604C: LAST detection of optical counterpart candidate
  61. GRB 260604C: SVOM detection of a long burst
  62. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  63. EP260602a: EP-FXT follow-up observation
  64. EP260603a: Einstein Probe detection of a fast X-ray transient
  65. EP260602d: Optical Upper limits with kinder observations
  66. EP260602b: Liverpool Telescope observations
  67. EP260602a: Liverpool Telescope optical upper limits
  68. EP260602b: Liverpool Telescope and LCO observations
  69. EP260602a: GTC and Liverpool Telescope optical observations
  70. Konus-Wind detection of GRB 260601B/EP260601a
  71. GRB 260601B / EP260601a: Mondy optical upper limit
  72. EP260602b: EP-FXT follow-up observation
  73. GRB 260603A: Kilonova-Catcher optical upper limit
  74. GRB 260603A: SVOM/VT optical observations
  75. EP260602a: NOT NIR J-band observations
  76. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  77. EP260602d: Einstein Probe detection of a fast X-ray transient
  78. GRB 260601A: SVOM/GRM observation of a short burst
  79. EP260602c: Einstein Probe detection of a fast X-ray transient
  80. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  81. EP260602a: COLIBRÍ optical observations
  82. GRB260601B/EP260601a: NOT near-infrared observations
  83. GRB 260603A: SVOM detection of a burst
  84. EP260602b: Einstein Probe detection of a fast X-ray transient
  85. EP260602a: SVOM/VT optical candidate
  86. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  87. GRB 260601B/EP260601a: J-band upper limit with WINTER
  88. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  89. EP260530a/AT 2026nwl: KAIT optical observations
  90. EP260602a: Optical upper limits with Kinder observations
  91. EP260602a: Einstein Probe detection of a fast X-ray transient
  92. GRB 260601B/EP260601a: SVOM/VT optical observations
  93. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  94. EP260601a: Einstein Probe detection of an X-ray transient
  95. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  96. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  97. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  98. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  99. GRB 260531B: GECAM-B observation
  100. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp

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