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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"

32510 results found.

  1. GRB 260502A: SVOM/GRM observation of a short GRB
  2. GRB 260503A: SVOM/GRM observation of a GRB
  3. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  5. GRB 260504B: REM optical/NIR observations
  6. IPN triangulation of GRB 260429A
  7. IPN triangulation of GRB 260428A
  8. GRB 260504B: AST3-2 i-band upper limit
  9. GRB 260504B: LCO z-band upper limit
  10. SVOM GRB 260504B: MASTER-OAFA optical observations
  11. Fermi GRB 260504A: Global MASTER-Net observations report
  12. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  13. GRB 260502A: GECAM-B observation of a short burst
  14. IPN triangulation of a bright burst from SGR 1E1841-045
  15. GRB 260429B / EP260429a: EP-FXT follow-up observation
  16. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  17. GRB 260429B / EP260429a: AstroSat CZTI detection
  18. EP260502a: BOOTES-7: early optical upper limit
  19. EP260502a: Las Cumbres upper limit
  20. GRB 260429A: SVOM/GRM observation of a short burst
  21. EP260429a: Global MASTER-Net observations report
  22. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  23. GRB 260424B: AstroSat CZTI detection
  24. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  25. EP260429a: LCO optical upper limits
  26. EP260430a: LCO optical upper limits
  27. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  28. Fermi GRB 260429A: Global MASTER-Net observations report
  29. EP260430a: Global MASTER-Net observations report
  30. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  31. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  32. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 260428A: AstroSat CZTI detection
  34. Fermi GRB 260428A: Global MASTER-Net observations report
  35. EP260416a: Mondy and Terskol optical upper limits
  36. GRB 260424B: Glowbug gamma-ray detection of a short burst
  37. GRB 260424B: COLIBRÍ optical upper limit
  38. Konus-Wind detection of GRB 260424B
  39. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  40. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  41. IPN triangulation of GRB 260424B (short)
  42. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  44. GRB 260401A: cubesat Avion detection
  45. EP260321a: Upper limits from ATCA radio observations
  46. GRB 260421B: Kilonova-Catcher optical afterglow detection
  47. GRB 260421B: Insight-HXMT/HE detection
  48. The EP-WXT trigger 01709258652: Mondy optical observations
  49. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  50. EP260416a: Mondy optical observations
  51. GRB 260421B: SVOM/ECLAIRs refined analysis
  52. GRB 260421B: 3.6m DOT optical observation
  53. EP260416a: ZTSh R band observations
  54. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  55. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  56. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  57. GRB 260419A: AstroSat CZTI detection
  58. GRB 260421B: SVOM/GRM observation
  59. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  60. GRB 260421B: EP-FXT follow-up observation
  61. GOTO26djh/AT2026jpw: ATCA radio detection
  62. GRB 260421B: J-band upper limit with WINTER
  63. GRB 260421B: LCO optical counterpart detection
  64. GRB 260421B: Fermi GBM Observation
  65. GRB 260421A: AstroSat CZTI detection
  66. GOTO26djh/AT2026jpw: radio detection at 15GHz
  67. GRB 260412A: SVOM/ECLAIRs refined analysis
  68. GRB 260421B: SVOM/VT optical observations
  69. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  70. GRB 260310A: Late-time Chandra X-ray Detection
  71. GRB 260418A: Insight-HXMT/HE detection
  72. EP260416a: 1.3m DFOT optical observation
  73. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  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: BOOTES-7 early optical afterglow detection
  79. GRB 260421B: LCO optical afterglow confirmation
  80. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  81. GRB 260421B: TRT optical counterpart detection
  82. GRB 260421B: SVOM detection of a long burst
  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. EP-WXT trigger 01709260303: KAIT optical observations
  89. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  90. GRB 260417A: SVOM/GRM observation
  91. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  92. EP260417a: GROWTH-India Telescope optical upper limit
  93. Fermi GRB 260417B: Global MASTER-Net observations report
  94. EP260417b: GROWTH-India Telescope optical upper limit
  95. EP260416a: Ondrejov D50 optical detection
  96. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  97. EP260417a: Global MASTER-Net observations report
  98. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  99. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  100. EP260416a: GMG Optical Observation

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