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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').
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"

15247 results found.

  1. GRB 260130A: GECAM-B observation of a short burst
  2. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  3. GRB 260127B: Insight-HXMT/HE detection
  4. GRB 260127B: GECAM-B observation of a short burst
  5. GRB 260127A: GECAM-B observation
  6. EP260131a: Liverpool Telescope optical upper limits
  7. EP260131a: COLIBRÍ further observations
  8. Konus-Wind detection of GRB 260128A / EP260128a
  9. GRB 260131A: Insight-HXMT/HE detection
  10. Konus-Wind detection of GRB 260131A/B
  11. EP260131a: COLIBRÍ observations of slow optical fading
  12. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  13. EP260131a: COLIBRÍ optical observations of the counterpart
  14. GRB 260127B: AstroSat CZTI detection
  15. GRB 260130A: Fermi GBM Detection
  16. GRB 260127B: Fermi GBM Detection
  17. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  18. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  19. GRB 260128B: SVOM detection of a burst through offline search
  20. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  21. EP260128a: NOT optical counterpart candidate
  22. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  23. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  24. GRB 260127A: Fermi GBM Observation
  25. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 260127A: COLIBRÍ optical observations
  27. GRB 260127A: NOT optical observations
  28. GRB 260127B: Swift ToO observations
  29. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  30. GRB 260127A: SVOM/C-GFT optical observations
  31. EP260126a: Optical upper limit with Kinder observations
  32. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  33. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  34. Konus-Wind detection of GRB 260120B
  35. GRB 251222A: SVOM/ECLAIRs refined analysis
  36. GRB 260125A: Swift ToO observations
  37. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 260114A: SVOM/VT optical upper limits
  39. GRB 260120A: AstroSat CZTI detection
  40. GRB 260120B: SVOM/GRM observation
  41. GRB 260120A: GECAM-B observation
  42. GRB 260120B: AstroSat CZTI detection
  43. GRB 260114A: Insight-HXMT/HE detection
  44. GRB 260122B: Swift detection of a burst
  45. EP260119a: Mondy and SAO RAS optical upper limits
  46. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  47. EP260116a: COLIBRÍ further observations
  48. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  49. GRB 260120B: Fermi GBM Observation
  50. EP260105a: GTC/HiPERCAM optical observations
  51. GRB 260120B: COLIBRÍ optical upper limits
  52. GRB 260101A: 239Alferov CubeSat detection
  53. EP260119a: Liverpool Telescope optical follow-up observations
  54. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  55. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  56. EP260119a: update of EP-FXT follow-up observation
  57. EP260119a: NOT optical observations
  58. EP260116a: COLIBRÍ detection of a fading optical source
  59. GRB 251208D: SVOM/ECLAIRs refined analysis
  60. GRB 251208D: SVOM/ECLAIRs refined analysis
  61. GRB 260117A: Swift-XRT afterglow detection
  62. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  63. GRB 260115A: AstroSat CZTI detection
  64. GRB 260117A: ZTSh optical upper limit
  65. EP260119a: COLIBRÍ optical counterpart candidate
  66. GRB 260110A: SVOM detection of a burst through offline search
  67. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  68. Swift trigger on the HMXB 1A 1118-61
  69. GRB 260117A: Swift ToO observations
  70. GRB 260117A: SVOM detection of a long faint burst
  71. EP 260116a: COLIBRÍ optical upper limit
  72. GRB 260115A: GECAM-B observation
  73. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  74. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  75. GRB 260114A: VLT/MUSE spectroscopic observations
  76. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  78. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  79. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  80. GRB260114A: STEP/T80S optical limits
  81. Konus-Wind detection of GRB 260114A
  82. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  83. GRB 260114A: COLIBRÍ optical upper limits
  84. GRB 260114A: TNG NIR upper limit
  85. GRB 260114A: NOT optical observations
  86. Konus-Wind detection of GRB 251230A / EP251230a
  87. GRB 260114A: SVOM/GRM observation of a short burst
  88. GRB 260114A: GECAM-B observation of a short burst
  89. GRB 260114A: Fermi GBM observation
  90. GRB 260112B: GECAM-B observation
  91. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  92. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  93. EP260110a: TRT optical upper limits
  94. Konus-Wind detection of GRB 260101A
  95. GRB 260111A: Swift-XRT observations
  96. Swift Trigger 1439093: is probably not GRB 260113A
  97. GRB 260111A: GECAM-B observation of a burst
  98. GRB 260111A: Fermi GBM Observation
  99. GRB 260111A: Swift ToO observations
  100. GRB 251230A: Mondy Optical Observations

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