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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').
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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"

20950 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  2. Fermi GRB 260628A: Global MASTER-Net observations report
  3. EP260628a: EP-WXT detection of a fast X-ray transient
  4. EP260626a: EP-WXT detection of a fast X-ray transient
  5. EP260623a: FTW optical and NIR observations
  6. GRB 260619A: SVOM/ECLAIRs refined analysis
  7. EP260623a: Liverpool Telescope optical observations
  8. EP260623a: WINTER J-band observations
  9. EP260623a: Optical follow-up observations with Kinder
  10. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  11. EP260623a: SVOM/VT optical observations
  12. EP260623a: TRT optical observations
  13. EP260623a: REM optical/NIR afterglow detection
  14. EP 260623a: COLIBRÍ optical observations
  15. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  16. EP260618a: Liverpool Telescope optical observations
  17. GRB 260619A: NOT optical observations
  18. GRB 260618B: LCO optical observations
  19. EP260618a: JinShan optical observations
  20. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  21. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  22. GRB 260619A: SVOM/VT optical counterpart confirmation
  23. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  24. GRB 260618B: SVOM/VT optical candidate
  25. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  26. EP260618a: OHP/T193 optical observations
  27. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  28. GRB 260619A: Kilonova-Catcher optical upper limit
  29. EP260618a: EP-FXT follow-up observation
  30. EP260618a: COLIBRÍ optical counterpart candidate
  31. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  32. EP260618a: EP-WXT detection of an X-ray transient
  33. GRB 260610B: AbAO optical observations
  34. EP260616a/GRB 260616B: EP-FXT follow-up observation
  35. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  36. GRB260616C: MAXI/GSC detection
  37. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  38. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  39. EP260616a: EP-WXT detection of a fast X-ray transient
  40. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  41. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  42. GRB 260614B: SVOM/ECLAIRs refined analysis
  43. GRB 260610B: Terskol optical observations
  44. GRB 260614B: SVOM/VT optical afterglow confirmation
  45. GRB 260610B: ALMA detection
  46. GRB 260610B: further Liverpool Telescope optical observations
  47. GRB 260610B / AT2026owq: GRANDMA optical observations
  48. GRB 260610B / AT2026owq: further SAO RAS optical observations
  49. EP260605a: COLIBRÍ optical upper limits
  50. GRB 260610b: Liverpool Telescope optical observations
  51. IceCube-260610A: No candidates from the Zwicky Transient Facility
  52. IceCube-260610A: EP-FXT follow-up observation
  53. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  54. GRB 260610B / AT2026owq: SVOM/VT optical observations
  55. GRB 260610B / AT2026owq: OASDG optical observations
  56. GRB 260610B: IAC-80 Optical observations
  57. GRB 260610B / AT2026owq: SAO RAS optical observations
  58. EP260610b: GTC likely spectroscopic redshift z = 1.10
  59. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  60. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  61. GRB 260610B / AT2026owq: Early ATLAS observations
  62. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  63. EP260610b: COLIBRÍ optical observations
  64. GRB 260610B: DDOTI optical observations
  65. EP260610b: MAO/AZT-22 optical observations
  66. GRB 260610B: GOTO optical counterpart candidate
  67. EP260610b: SVOM/VT optical confirmation with blue color
  68. GRB 260515A: SOAR optical observations
  69. EP260610b: Gemini North optical counterpart candidate
  70. GRB 260604C: SVOM/ECLAIRs refined analysis
  71. GRB 260608A: SVOM/ECLAIRs refined analysis
  72. GRB 260604C: further SAO RAS optical observations
  73. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  74. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  75. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  76. GRB 260604C: SVOM/C-GFT upper limit
  77. GRB 260607A: TRT optical observations
  78. GRB 260604C: GRANDMA further observations
  79. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  80. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  81. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  82. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  83. GRB 260604C: 6 GHz VLA observations
  84. GRB 260604C: SAO RAS optical observations
  85. GRB 260604C: GRANDMA observations
  86. GRB260603A: SVOM/ECLAIRs refined analysis
  87. GRB 260604C: Liverpool Telescope optical detection
  88. EP260602d: EP-FXT follow-up observation
  89. GRB 260527A/EP260527a: 6 GHz VLA observations
  90. GRB 260604C: GOTO detections of the optical afterglow
  91. GRB 260604C: Kilonova-Catcher optical afterglow detection
  92. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  93. GRB 260604C: Jinshan optical observations
  94. EP260602d: J-band upper limit with WINTER
  95. EP260602b: J-band upper limit with WINTER
  96. GRB 260604C: LAST detection of optical counterpart candidate
  97. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  98. Fermi GRB 260604C: Global MASTER-Net observations report
  99. Fermi GRB 260604C: Global MASTER-Net observations report
  100. SVOM GRB260604.85: Global MASTER-Net observations report

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