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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"

32706 results found.

  1. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  2. GRB 260504B: REM optical/NIR observations
  3. IPN triangulation of GRB 260429A
  4. IPN triangulation of GRB 260428A
  5. GRB 260504B: AST3-2 i-band upper limit
  6. GRB 260504B: LCO z-band upper limit
  7. SVOM GRB 260504B: MASTER-OAFA optical observations
  8. Fermi GRB 260504A: Global MASTER-Net observations report
  9. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  10. GRB 260502A: GECAM-B observation of a short burst
  11. IPN triangulation of a bright burst from SGR 1E1841-045
  12. GRB 260429B / EP260429a: EP-FXT follow-up observation
  13. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  14. GRB 260429B / EP260429a: AstroSat CZTI detection
  15. EP260502a: BOOTES-7: early optical upper limit
  16. EP260502a: Las Cumbres upper limit
  17. GRB 260429A: SVOM/GRM observation of a short burst
  18. EP260429a: Global MASTER-Net observations report
  19. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  20. GRB 260424B: AstroSat CZTI detection
  21. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  22. EP260429a: LCO optical upper limits
  23. EP260430a: LCO optical upper limits
  24. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  25. Fermi GRB 260429A: Global MASTER-Net observations report
  26. EP260430a: Global MASTER-Net observations report
  27. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  28. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  29. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 260428A: AstroSat CZTI detection
  31. Fermi GRB 260428A: Global MASTER-Net observations report
  32. EP260416a: Mondy and Terskol optical upper limits
  33. GRB 260424B: Glowbug gamma-ray detection of a short burst
  34. GRB 260424B: COLIBRÍ optical upper limit
  35. Konus-Wind detection of GRB 260424B
  36. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  37. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  38. IPN triangulation of GRB 260424B (short)
  39. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  41. GRB 260401A: cubesat Avion detection
  42. EP260321a: Upper limits from ATCA radio observations
  43. GRB 260421B: Kilonova-Catcher optical afterglow detection
  44. GRB 260421B: Insight-HXMT/HE detection
  45. The EP-WXT trigger 01709258652: Mondy optical observations
  46. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  47. EP260416a: Mondy optical observations
  48. GRB 260421B: SVOM/ECLAIRs refined analysis
  49. GRB 260421B: 3.6m DOT optical observation
  50. EP260416a: ZTSh R band observations
  51. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  52. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  53. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  54. GRB 260419A: AstroSat CZTI detection
  55. GRB 260421B: SVOM/GRM observation
  56. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  57. GRB 260421B: EP-FXT follow-up observation
  58. GOTO26djh/AT2026jpw: ATCA radio detection
  59. GRB 260421B: J-band upper limit with WINTER
  60. GRB 260421B: LCO optical counterpart detection
  61. GRB 260421B: Fermi GBM Observation
  62. GRB 260421A: AstroSat CZTI detection
  63. GOTO26djh/AT2026jpw: radio detection at 15GHz
  64. GRB 260412A: SVOM/ECLAIRs refined analysis
  65. GRB 260421B: SVOM/VT optical observations
  66. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  67. GRB 260310A: Late-time Chandra X-ray Detection
  68. GRB 260418A: Insight-HXMT/HE detection
  69. EP260416a: 1.3m DFOT optical observation
  70. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  71. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  72. Fermi GRB 260421C: Global MASTER-Net observations report
  73. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  74. Fermi GRB 260421B: Global MASTER-Net observations report
  75. GRB 260421B: BOOTES-7 early optical afterglow detection
  76. GRB 260421B: LCO optical afterglow confirmation
  77. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  78. GRB 260421B: TRT optical counterpart detection
  79. GRB 260421B: SVOM detection of a long burst
  80. Fermi GRB 260421A: Global MASTER-Net observations report
  81. EP260321a: VLA radio follow-up
  82. GRB 260412A: LCOGT Optical Upper Limits
  83. EP260416a: Optical follow-up observations with Kinder
  84. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  85. EP-WXT trigger 01709260303: KAIT optical observations
  86. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  87. GRB 260417A: SVOM/GRM observation
  88. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  89. EP260417a: GROWTH-India Telescope optical upper limit
  90. Fermi GRB 260417B: Global MASTER-Net observations report
  91. EP260417b: GROWTH-India Telescope optical upper limit
  92. EP260416a: Ondrejov D50 optical detection
  93. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  94. EP260417a: Global MASTER-Net observations report
  95. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  96. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  97. EP260416a: GMG Optical Observation
  98. Fermi GRB 260417A: Global MASTER-Net observations report
  99. Konus-Wind detection of GRB 260411B
  100. GRB 260417A: AstroSat CZTI detection

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