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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"

28052 results found.

  1. GRB 260509A: Liverpool Telescope optical observations
  2. GRB 260510B: SVOM detection of a burst
  3. GRB 260509A: LCO optical observations
  4. SVOM GRB 260509A: MASTER-OAFA optical observation
  5. Fermi GRB 260510A: Global MASTER-Net observations report
  6. GRB 260509A: KAIT optical observations
  7. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  8. GRB 260509A: SVOM/VT optical candidate with VHF data
  9. GRB 260509A: LCO optical counterpart detection
  10. GRB 260509A: SVOM detection of a burst
  11. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  12. EP260507a: REM optical/NIR observations
  13. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  14. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  15. EP260507a: COLIBRÍ optical observations
  16. EP260507a: NOT optical observations
  17. EP260507a: further Liverpool Telescope observations
  18. EP260507a: Liverpool Telescope optical upper limits
  19. EP260507a: TRT optical counterpart detection
  20. EP260507a: Kinder optical counterpart candidate
  21. EP260507a: LCO optical counterpart
  22. EP260507a: Einstein Probe detection of an X-ray transient
  23. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  24. Fermi GRB 260506A: Global MASTER-Net observations report
  25. IceCube Alert 260505A: Global MASTER-Net observations report
  26. GRB 260430B: Glowbug gamma-ray detection
  27. GRB 260421B: radio observation with the VLA
  28. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  29. GRB 260430B: AstroSat CZTI detection of a long burst
  30. GRB 260502A: SVOM/GRM observation of a short GRB
  31. GRB 260503A: SVOM/GRM observation of a GRB
  32. Konus-Wind detection of GRB 260411C
  33. GRB 260504B: REM optical/NIR observations
  34. GRB 260504B: LCO z-band upper limit
  35. SVOM GRB 260504B: MASTER-OAFA optical observations
  36. GRB 260504B: SVOM detection of a short burst
  37. Fermi GRB 260504A: Global MASTER-Net observations report
  38. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  39. GRB 260429B / EP260429a: EP-FXT follow-up observation
  40. EP260502a: Einstein Probe detection of an X-ray transient
  41. GRB 260429A: SVOM/GRM observation of a short burst
  42. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  43. EP260429a: Global MASTER-Net observations report
  44. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  45. GRB 260424B: AstroSat CZTI detection
  46. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  47. EP260429a: LCO optical upper limits
  48. EP260430a: LCO optical upper limits
  49. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  50. GRB 260429A: Fermi GBM Detection
  51. Fermi GRB 260429A: Global MASTER-Net observations report
  52. EP260430a: Global MASTER-Net observations report
  53. EP260430a: Einstein Probe detection of an X-ray transient
  54. EP260429a: EP-WXT detection of a fast X-ray transient
  55. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  56. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  57. Fermi GRB 260428A: Global MASTER-Net observations report
  58. EP260416a: Mondy and Terskol optical upper limits
  59. GRB 260424B: Glowbug gamma-ray detection of a short burst
  60. GRB 260424B: COLIBRÍ optical upper limit
  61. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  62. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  63. IceCube Alert 260425A: Global MASTER-Net observations report
  64. Fermi trigger No 798737427: Global MASTER-Net observations report
  65. GRB 260401A: cubesat Avion detection
  66. EP260321a: Upper limits from ATCA radio observations
  67. GRB 260421B: Kilonova-Catcher optical afterglow detection
  68. The EP-WXT trigger 01709258652: Mondy optical observations
  69. EP260416a: Mondy optical observations
  70. GRB 260421B: 3.6m DOT optical observation
  71. EP260416a: ZTSh R band observations
  72. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 260421B: SVOM/GRM observation
  74. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  75. GRB 260421B: EP-FXT follow-up observation
  76. GOTO26djh/AT2026jpw: ATCA radio detection
  77. GRB 260421B: J-band upper limit with WINTER
  78. GRB 260421B: LCO optical counterpart detection
  79. GRB 260421B: Fermi GBM Observation
  80. GOTO26djh/AT2026jpw: radio detection at 15GHz
  81. GRB 260421B: SVOM/VT optical observations
  82. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  83. GRB 260310A: Late-time Chandra X-ray Detection
  84. EP260416a: 1.3m DFOT optical observation
  85. Fermi GRB 260421C: Global MASTER-Net observations report
  86. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  87. Fermi GRB 260421B: Global MASTER-Net observations report
  88. GRB 260421B: LCO optical afterglow confirmation
  89. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  90. GRB 260421B: TRT optical counterpart detection
  91. GRB 260421B: SVOM detection of a long burst
  92. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  93. Fermi GRB 260421A: Global MASTER-Net observations report
  94. EP260321a: VLA radio follow-up
  95. GRB 260412A: LCOGT Optical Upper Limits
  96. EP260416a: Optical follow-up observations with Kinder
  97. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  98. GRB 260417A: SVOM/GRM observation
  99. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  100. Fermi trigger No 798275385: Global MASTER-Net observations report

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