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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"

19290 results found.

  1. GRB 260428A: AstroSat CZTI detection
  2. Fermi GRB 260428A: Global MASTER-Net observations report
  3. EP260416a: Mondy and Terskol optical upper limits
  4. GRB 260424B: Glowbug gamma-ray detection of a short burst
  5. GRB 260424B: COLIBRÍ optical upper limit
  6. GRB 260428A: Fermi GBM Final Real-time Localization
  7. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  8. GRB 260424C: Fermi GBM Final Localization
  9. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  10. GRB 260424B: SVOM/GRM detection of a short burst
  11. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  13. IceCube Alert 260425A: Global MASTER-Net observations report
  14. Fermi trigger No 798737427: Global MASTER-Net observations report
  15. GRB 260401A: cubesat Avion detection
  16. GRB 260424A: AstroSat CZTI detection of a long burst
  17. EP260321a: Upper limits from ATCA radio observations
  18. GRB 260421B: Insight-HXMT/HE detection
  19. The EP-WXT trigger 01709258652: Mondy optical observations
  20. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  21. EP260416a: Mondy optical observations
  22. GRB 260421B: SVOM/ECLAIRs refined analysis
  23. GRB 260421B: 3.6m DOT optical observation
  24. EP260416a: ZTSh R band observations
  25. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  26. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  27. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  28. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  29. GRB 260419A: AstroSat CZTI detection
  30. GRB 260421B: SVOM/GRM observation
  31. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  32. GRB 260421B: EP-FXT follow-up observation
  33. The EP-WXT trigger 01709260362 is likely a flaring star
  34. GOTO26djh/AT2026jpw: ATCA radio detection
  35. GRB 260421B: J-band upper limit with WINTER
  36. GRB 260421B: LCO optical counterpart detection
  37. GRB 260421B: Fermi GBM Observation
  38. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  39. GRB 260421A: AstroSat CZTI detection
  40. GOTO26djh/AT2026jpw: radio detection at 15GHz
  41. GRB 260412A: SVOM/ECLAIRs refined analysis
  42. GRB 260421B: SVOM/VT optical observations
  43. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  44. GRB 260310A: Late-time Chandra X-ray Detection
  45. GRB 260418A: Insight-HXMT/HE detection
  46. EP260416a: 1.3m DFOT optical observation
  47. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  49. Fermi GRB 260421C: Global MASTER-Net observations report
  50. GRB 260421C: Fermi GBM Final Real-time Localization
  51. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  52. Fermi GRB 260421B: Global MASTER-Net observations report
  53. GRB 260421B: BOOTES-7 early optical afterglow detection
  54. GRB 260421B: LCO optical afterglow confirmation
  55. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  56. GRB 260421B: SVOM detection of a long burst
  57. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  58. GRB 260421B: Fermi GBM Final Real-time Localization
  59. Fermi GRB 260421A: Global MASTER-Net observations report
  60. GRB 260421A: Fermi GBM Final Real-time Localization
  61. GRB 260412A: LCOGT Optical Upper Limits
  62. The EP-WXT trigger 01709260314 is likely a flaring star
  63. EP260416a: Optical follow-up observations with Kinder
  64. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  65. The EP-WXT trigger 01709260303 is likely a flaring star
  66. GRB 260417A: SVOM/GRM observation
  67. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  68. GRB 260419B: Fermi GBM Final Real-time Localization
  69. GRB 260419A: Fermi GBM Final Real-time Localization
  70. Fermi trigger No 798275385: Global MASTER-Net observations report
  71. EP260417a: GROWTH-India Telescope optical upper limit
  72. Fermi GRB 260417B: Global MASTER-Net observations report
  73. EP260417b: GROWTH-India Telescope optical upper limit
  74. EP260416a: Ondrejov D50 optical detection
  75. GRB 260418B: Fermi GBM Final Real-time Localization
  76. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  77. EP260417a: Global MASTER-Net observations report
  78. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  79. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  80. GRB 260418A: Fermi GBM Final Real-time Localization
  81. EP260416a: GMG Optical Observation
  82. Fermi GRB 260417A: Global MASTER-Net observations report
  83. GRB 260417B: Fermi GBM Final Real-time Localization
  84. GRB 260417A: AstroSat CZTI detection
  85. EP260416a: LCO observations confirm end of flaring phase
  86. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  87. EP260417a: Einstein Probe detection of an X-ray transient
  88. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  89. EP260417b: Einstein Probe detection of a fast X-ray transient
  90. GRB 260414A: Insight-HXMT/HE detection
  91. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  92. EP260416a: WFST optical observations and rebrightening
  93. GRB 260417A: Fermi GBM Final Real-time Localization
  94. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  95. EP260416a: SVOM/VT optical observation
  96. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  97. GRB 260415B: Glowbug gamma-ray detection
  98. GRB 260411B: Glowbug gamma-ray detection
  99. GRB 260415A: Insight-HXMT/HE detection
  100. EP260416a: COLIBRÍ optical counterpart candidate

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