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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"

27241 results found.

  1. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  2. EP260507a: REM optical/NIR observations
  3. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  5. EP260507a: COLIBRÍ optical observations
  6. EP260507a: NOT optical observations
  7. EP260507a: further Liverpool Telescope observations
  8. EP260507a: Liverpool Telescope optical upper limits
  9. EP260507a: TRT optical counterpart detection
  10. EP260507a: Kinder optical counterpart candidate
  11. EP260507a: LCO optical counterpart
  12. EP260507a: Einstein Probe detection of an X-ray transient
  13. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  14. Fermi GRB 260506A: Global MASTER-Net observations report
  15. IceCube Alert 260505A: Global MASTER-Net observations report
  16. GRB 260430B: Glowbug gamma-ray detection
  17. GRB 260421B: radio observation with the VLA
  18. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  19. GRB 260430B: AstroSat CZTI detection of a long burst
  20. GRB 260502A: SVOM/GRM observation of a short GRB
  21. GRB 260503A: SVOM/GRM observation of a GRB
  22. Konus-Wind detection of GRB 260411C
  23. GRB 260504B: REM optical/NIR observations
  24. GRB 260504B: LCO z-band upper limit
  25. SVOM GRB 260504B: MASTER-OAFA optical observations
  26. GRB 260504B: SVOM detection of a short burst
  27. Fermi GRB 260504A: Global MASTER-Net observations report
  28. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  29. GRB 260429B / EP260429a: EP-FXT follow-up observation
  30. EP260502a: Einstein Probe detection of an X-ray transient
  31. GRB 260429A: SVOM/GRM observation of a short burst
  32. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  33. EP260429a: Global MASTER-Net observations report
  34. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  35. GRB 260424B: AstroSat CZTI detection
  36. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  37. EP260429a: LCO optical upper limits
  38. EP260430a: LCO optical upper limits
  39. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  40. GRB 260429A: Fermi GBM Detection
  41. Fermi GRB 260429A: Global MASTER-Net observations report
  42. EP260430a: Global MASTER-Net observations report
  43. EP260430a: Einstein Probe detection of an X-ray transient
  44. EP260429a: EP-WXT detection of a fast X-ray transient
  45. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  46. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  47. Fermi GRB 260428A: Global MASTER-Net observations report
  48. EP260416a: Mondy and Terskol optical upper limits
  49. GRB 260424B: Glowbug gamma-ray detection of a short burst
  50. GRB 260424B: COLIBRÍ optical upper limit
  51. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  52. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  53. IceCube Alert 260425A: Global MASTER-Net observations report
  54. Fermi trigger No 798737427: Global MASTER-Net observations report
  55. GRB 260401A: cubesat Avion detection
  56. EP260321a: Upper limits from ATCA radio observations
  57. GRB 260421B: Kilonova-Catcher optical afterglow detection
  58. The EP-WXT trigger 01709258652: Mondy optical observations
  59. EP260416a: Mondy optical observations
  60. GRB 260421B: 3.6m DOT optical observation
  61. EP260416a: ZTSh R band observations
  62. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 260421B: SVOM/GRM observation
  64. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  65. GRB 260421B: EP-FXT follow-up observation
  66. GOTO26djh/AT2026jpw: ATCA radio detection
  67. GRB 260421B: J-band upper limit with WINTER
  68. GRB 260421B: LCO optical counterpart detection
  69. GRB 260421B: Fermi GBM Observation
  70. GOTO26djh/AT2026jpw: radio detection at 15GHz
  71. GRB 260421B: SVOM/VT optical observations
  72. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  73. GRB 260310A: Late-time Chandra X-ray Detection
  74. EP260416a: 1.3m DFOT optical observation
  75. Fermi GRB 260421C: Global MASTER-Net observations report
  76. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  77. Fermi GRB 260421B: Global MASTER-Net observations report
  78. GRB 260421B: LCO optical afterglow confirmation
  79. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  80. GRB 260421B: TRT optical counterpart detection
  81. GRB 260421B: SVOM detection of a long burst
  82. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  83. Fermi GRB 260421A: Global MASTER-Net observations report
  84. EP260321a: VLA radio follow-up
  85. GRB 260412A: LCOGT Optical Upper Limits
  86. EP260416a: Optical follow-up observations with Kinder
  87. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  88. GRB 260417A: SVOM/GRM observation
  89. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  90. Fermi trigger No 798275385: Global MASTER-Net observations report
  91. EP260417a: GROWTH-India Telescope optical upper limit
  92. Fermi GRB 260417B: Global MASTER-Net observations report
  93. EP260417b: GROWTH-India Telescope optical upper limit
  94. EP260416a: Ondrejov D50 optical detection
  95. EP260417a: Global MASTER-Net observations report
  96. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  97. EP260416a: GMG Optical Observation
  98. Fermi GRB 260417A: Global MASTER-Net observations report
  99. EP260416a: LCO observations confirm end of flaring phase
  100. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope

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