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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"

20951 results found.

  1. Fermi trigger No 804552016: Global MASTER-Net observations report
  2. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  3. Fermi GRB 260628A: Global MASTER-Net observations report
  4. EP260628a: EP-WXT detection of a fast X-ray transient
  5. EP260626a: EP-WXT detection of a fast X-ray transient
  6. EP260623a: FTW optical and NIR observations
  7. GRB 260619A: SVOM/ECLAIRs refined analysis
  8. EP260623a: Liverpool Telescope optical observations
  9. EP260623a: WINTER J-band observations
  10. EP260623a: Optical follow-up observations with Kinder
  11. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  12. EP260623a: SVOM/VT optical observations
  13. EP260623a: TRT optical observations
  14. EP260623a: REM optical/NIR afterglow detection
  15. EP 260623a: COLIBRÍ optical observations
  16. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  17. EP260618a: Liverpool Telescope optical observations
  18. GRB 260619A: NOT optical observations
  19. GRB 260618B: LCO optical observations
  20. EP260618a: JinShan optical observations
  21. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  22. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  23. GRB 260619A: SVOM/VT optical counterpart confirmation
  24. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  25. GRB 260618B: SVOM/VT optical candidate
  26. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  27. EP260618a: OHP/T193 optical observations
  28. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  29. GRB 260619A: Kilonova-Catcher optical upper limit
  30. EP260618a: EP-FXT follow-up observation
  31. EP260618a: COLIBRÍ optical counterpart candidate
  32. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  33. EP260618a: EP-WXT detection of an X-ray transient
  34. GRB 260610B: AbAO optical observations
  35. EP260616a/GRB 260616B: EP-FXT follow-up observation
  36. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  37. GRB260616C: MAXI/GSC detection
  38. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  39. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  40. EP260616a: EP-WXT detection of a fast X-ray transient
  41. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  42. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  43. GRB 260614B: SVOM/ECLAIRs refined analysis
  44. GRB 260610B: Terskol optical observations
  45. GRB 260614B: SVOM/VT optical afterglow confirmation
  46. GRB 260610B: ALMA detection
  47. GRB 260610B: further Liverpool Telescope optical observations
  48. GRB 260610B / AT2026owq: GRANDMA optical observations
  49. GRB 260610B / AT2026owq: further SAO RAS optical observations
  50. EP260605a: COLIBRÍ optical upper limits
  51. GRB 260610b: Liverpool Telescope optical observations
  52. IceCube-260610A: No candidates from the Zwicky Transient Facility
  53. IceCube-260610A: EP-FXT follow-up observation
  54. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  55. GRB 260610B / AT2026owq: SVOM/VT optical observations
  56. GRB 260610B / AT2026owq: OASDG optical observations
  57. GRB 260610B: IAC-80 Optical observations
  58. GRB 260610B / AT2026owq: SAO RAS optical observations
  59. EP260610b: GTC likely spectroscopic redshift z = 1.10
  60. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  61. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  62. GRB 260610B / AT2026owq: Early ATLAS observations
  63. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  64. EP260610b: COLIBRÍ optical observations
  65. GRB 260610B: DDOTI optical observations
  66. EP260610b: MAO/AZT-22 optical observations
  67. GRB 260610B: GOTO optical counterpart candidate
  68. EP260610b: SVOM/VT optical confirmation with blue color
  69. GRB 260515A: SOAR optical observations
  70. EP260610b: Gemini North optical counterpart candidate
  71. GRB 260604C: SVOM/ECLAIRs refined analysis
  72. GRB 260608A: SVOM/ECLAIRs refined analysis
  73. GRB 260604C: further SAO RAS optical observations
  74. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  75. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  76. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  77. GRB 260604C: SVOM/C-GFT upper limit
  78. GRB 260607A: TRT optical observations
  79. GRB 260604C: GRANDMA further observations
  80. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  81. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  82. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  83. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  84. GRB 260604C: 6 GHz VLA observations
  85. GRB 260604C: SAO RAS optical observations
  86. GRB 260604C: GRANDMA observations
  87. GRB260603A: SVOM/ECLAIRs refined analysis
  88. GRB 260604C: Liverpool Telescope optical detection
  89. EP260602d: EP-FXT follow-up observation
  90. GRB 260527A/EP260527a: 6 GHz VLA observations
  91. GRB 260604C: GOTO detections of the optical afterglow
  92. GRB 260604C: Kilonova-Catcher optical afterglow detection
  93. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  94. GRB 260604C: Jinshan optical observations
  95. EP260602d: J-band upper limit with WINTER
  96. EP260602b: J-band upper limit with WINTER
  97. GRB 260604C: LAST detection of optical counterpart candidate
  98. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  99. Fermi GRB 260604C: Global MASTER-Net observations report
  100. Fermi GRB 260604C: Global MASTER-Net observations report

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