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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32702 results found.

  1. GRB 260504B: AST3-2 i-band upper limit
  2. GRB 260504B: LCO z-band upper limit
  3. SVOM GRB 260504B: MASTER-OAFA optical observations
  4. Fermi GRB 260504A: Global MASTER-Net observations report
  5. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  6. GRB 260502A: GECAM-B observation of a short burst
  7. IPN triangulation of a bright burst from SGR 1E1841-045
  8. GRB 260429B / EP260429a: EP-FXT follow-up observation
  9. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  10. GRB 260429B / EP260429a: AstroSat CZTI detection
  11. EP260502a: BOOTES-7: early optical upper limit
  12. EP260502a: Las Cumbres upper limit
  13. GRB 260429A: SVOM/GRM observation of a short burst
  14. EP260429a: Global MASTER-Net observations report
  15. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  16. GRB 260424B: AstroSat CZTI detection
  17. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  18. EP260429a: LCO optical upper limits
  19. EP260430a: LCO optical upper limits
  20. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  21. Fermi GRB 260429A: Global MASTER-Net observations report
  22. EP260430a: Global MASTER-Net observations report
  23. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  24. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  25. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 260428A: AstroSat CZTI detection
  27. Fermi GRB 260428A: Global MASTER-Net observations report
  28. EP260416a: Mondy and Terskol optical upper limits
  29. GRB 260424B: Glowbug gamma-ray detection of a short burst
  30. GRB 260424B: COLIBRÍ optical upper limit
  31. Konus-Wind detection of GRB 260424B
  32. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  33. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  34. IPN triangulation of GRB 260424B (short)
  35. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  37. GRB 260401A: cubesat Avion detection
  38. EP260321a: Upper limits from ATCA radio observations
  39. GRB 260421B: Kilonova-Catcher optical afterglow detection
  40. GRB 260421B: Insight-HXMT/HE detection
  41. The EP-WXT trigger 01709258652: Mondy optical observations
  42. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  43. EP260416a: Mondy optical observations
  44. GRB 260421B: SVOM/ECLAIRs refined analysis
  45. GRB 260421B: 3.6m DOT optical observation
  46. EP260416a: ZTSh R band observations
  47. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  48. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  49. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  50. GRB 260419A: AstroSat CZTI detection
  51. GRB 260421B: SVOM/GRM observation
  52. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  53. GRB 260421B: EP-FXT follow-up observation
  54. GOTO26djh/AT2026jpw: ATCA radio detection
  55. GRB 260421B: J-band upper limit with WINTER
  56. GRB 260421B: LCO optical counterpart detection
  57. GRB 260421B: Fermi GBM Observation
  58. GRB 260421A: AstroSat CZTI detection
  59. GOTO26djh/AT2026jpw: radio detection at 15GHz
  60. GRB 260412A: SVOM/ECLAIRs refined analysis
  61. GRB 260421B: SVOM/VT optical observations
  62. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  63. GRB 260310A: Late-time Chandra X-ray Detection
  64. GRB 260418A: Insight-HXMT/HE detection
  65. EP260416a: 1.3m DFOT optical observation
  66. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  68. Fermi GRB 260421C: Global MASTER-Net observations report
  69. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  70. Fermi GRB 260421B: Global MASTER-Net observations report
  71. GRB 260421B: BOOTES-7 early optical afterglow detection
  72. GRB 260421B: LCO optical afterglow confirmation
  73. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  74. GRB 260421B: TRT optical counterpart detection
  75. GRB 260421B: SVOM detection of a long burst
  76. Fermi GRB 260421A: Global MASTER-Net observations report
  77. EP260321a: VLA radio follow-up
  78. GRB 260412A: LCOGT Optical Upper Limits
  79. EP260416a: Optical follow-up observations with Kinder
  80. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  81. EP-WXT trigger 01709260303: KAIT optical observations
  82. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  83. GRB 260417A: SVOM/GRM observation
  84. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  85. EP260417a: GROWTH-India Telescope optical upper limit
  86. Fermi GRB 260417B: Global MASTER-Net observations report
  87. EP260417b: GROWTH-India Telescope optical upper limit
  88. EP260416a: Ondrejov D50 optical detection
  89. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  90. EP260417a: Global MASTER-Net observations report
  91. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  92. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  93. EP260416a: GMG Optical Observation
  94. Fermi GRB 260417A: Global MASTER-Net observations report
  95. Konus-Wind detection of GRB 260411B
  96. GRB 260417A: AstroSat CZTI detection
  97. IPN triangulation of GRB 260411B
  98. EP260416a: LCO observations confirm end of flaring phase
  99. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  100. EP260417a: TRT optical counterpart detection

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