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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"

32688 results found.

  1. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  2. GRB 260127B: GOTO candidate optical counterpart
  3. GRB 260127A: SVOM/C-GFT optical observations
  4. Fermi GRB 260127B: Global MASTER-Net observations report
  5. Swift GRB 260127A: Global MASTER-Net observations report
  6. GRB 260127A: LCO optical afterglow discovery
  7. GRB 260125A: Swift-XRT observations
  8. EP260126a: EP-FXT follow-up observation
  9. EP260126a: Optical upper limit with Kinder observations
  10. EP260126a: Liverpool Telescope optical upper limits
  11. EP260126a: Further NOT optical upper limits
  12. EP260126a: COLIBRÍ optical upper limits
  13. EP260126a: NOT optical observations
  14. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  15. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  16. Konus-Wind detection of GRB 260120B
  17. GRB 251222A: SVOM/ECLAIRs refined analysis
  18. GRB 260125A: Swift ToO observations
  19. GRB 260125A: GOTO candidate optical counterpart
  20. Fermi GRB 260125B: Global MASTER-Net observations report
  21. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 260114A: SVOM/VT optical upper limits
  23. GRB 260120A: AstroSat CZTI detection
  24. GRB 260122B: Swift-BAT refined analysis
  25. GRB 260120B: SVOM/GRM observation
  26. GRB 260120A: GECAM-B observation
  27. GRB 260120B: AstroSat CZTI detection
  28. GRB 260114A: Insight-HXMT/HE detection
  29. EP260119a: Assy AZT-20 optical observations
  30. EP260119a: Mondy and SAO RAS optical upper limits
  31. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  32. EP260119a: Xinglong optical upper limit
  33. Fermi GRB 260120C: Global MASTER-Net observations report
  34. GRB 260120B: Swift-BAT refined analysis
  35. EP260116a: COLIBRÍ further observations
  36. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  37. GRB 260120B: Fermi GBM Observation
  38. EP260105a: GTC/HiPERCAM optical observations
  39. GRB 260120B: Swift/UVOT Detection
  40. GRB 260120B: COLIBRÍ optical upper limits
  41. GRB 260120B: SVOM/C-GFT optical counterpart detection
  42. GRB 260101A: 239Alferov CubeSat detection
  43. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  44. EP260119A: Mondy I-Band Observations
  45. GRB 260114A: Swift/UVOT Upper Limits
  46. EP260119a: Liverpool Telescope optical follow-up observations
  47. GRB 251202A: further radio observations with the VLA
  48. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  49. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  50. EP260119a: KAIT optical observations
  51. EP260119a: SVOM/VT optical observation
  52. EP260119a: update of EP-FXT follow-up observation
  53. EP260119a: NOT optical observations
  54. EP260119a: SAO RAS optical observations
  55. EP260116a: COLIBRÍ detection of a fading optical source
  56. GRB 251208D: SVOM/ECLAIRs refined analysis
  57. GRB 251208D: SVOM/ECLAIRs refined analysis
  58. GRB 260117A: Swift-XRT afterglow detection
  59. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  60. EP260119a: Global MASTER-Net observations report
  61. GRB 260115A: AstroSat CZTI detection
  62. EP260119a: LCO optical observations
  63. GRB 260117A: ZTSh optical upper limit
  64. EP260119a: COLIBRÍ optical counterpart candidate
  65. EP260119a: preliminary result from the EP-FXT observation
  66. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  67. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  68. Swift trigger on the HMXB 1A 1118-61
  69. GRB 260117A: SVOM/VT optical candidate
  70. GRB 260117A: SVOM/C-GFT upper limit
  71. GRB 260117A: Swift ToO observations
  72. EP 260116a: COLIBRÍ optical upper limit
  73. GRB 260115A: GECAM-B observation
  74. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  75. EP260116a: Liverpool Telescope upper limits
  76. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  77. EP260116A: 1.3m DFOT optical upper limit
  78. GRB 260114A: VLT/MUSE spectroscopic observations
  79. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  80. EP260116a: Global MASTER-Net observations report
  81. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  82. EP260116a: Xinglong optical upper limit
  83. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  84. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  85. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  86. Fermi GRB 260115A: Global MASTER-Net observations report
  87. GRB260114A: STEP/T80S optical limits
  88. GRB 251222A: radio detection with the VLA
  89. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  90. Konus-Wind detection of GRB 260114A
  91. GRB 260114A: 6 GHz VLA observations
  92. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  93. GRB 260114A : MITSuME Akeno optical upper limits
  94. GRB 260114A: COLIBRÍ optical upper limits
  95. GRB 260114A: TNG NIR upper limit
  96. GRB 260114A: NOT optical observations
  97. Konus-Wind detection of GRB 251230A / EP251230a
  98. GRB 260114A: SVOM/GRM observation of a short burst
  99. Swift GRB 260114A: Global MASTER-Net observations report
  100. GRB 260114A: GECAM-B observation of a short burst

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