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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

38642 results found.

  1. GRB 260127A: Prompt enhanced Swift-XRT position
  2. GRB 260127A: LCO optical afterglow discovery
  3. GRB 260127A: Swift detection of a burst
  4. GRB 260127A: Fermi GBM Final Real-time Localization
  5. GRB 260125A: Swift-XRT observations
  6. EP260126a: EP-FXT follow-up observation
  7. EP260126a: Optical upper limit with Kinder observations
  8. EP260126a: Liverpool Telescope optical upper limits
  9. EP260126a: Further NOT optical upper limits
  10. EP260126a: COLIBRÍ optical upper limits
  11. EP260126a: NOT optical observations
  12. EP260126a: Einstein Probe detection of a fast X-ray transient
  13. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  14. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  15. Konus-Wind detection of GRB 260120B
  16. GRB 251222A: SVOM/ECLAIRs refined analysis
  17. GRB 260125A: Swift ToO observations
  18. GRB 260125A: GOTO candidate optical counterpart
  19. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 260125B: Fermi GBM Final Real-time Localization
  21. GRB 260125A: Fermi GBM Final Real-time Localization
  22. GRB 260114A: SVOM/VT optical upper limits
  23. GRB 260120A: AstroSat CZTI detection
  24. GRB 260120B: SVOM/GRM observation
  25. GRB 260120A: GECAM-B observation
  26. GRB 260120B: AstroSat CZTI detection
  27. GRB 260114A: Insight-HXMT/HE detection
  28. GRB 260122B: Swift detection of a burst
  29. EP260119a: Assy AZT-20 optical observations
  30. EP260119a: Mondy and SAO RAS optical upper limits
  31. GRB 260122A: Fermi GBM Final Real-time Localization
  32. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  33. EP260119a: Xinglong optical upper limit
  34. The EP-WXT trigger 01709251871 is likely a flaring star
  35. GRB 260120B: Swift-XRT refined Analysis
  36. EP260116a: COLIBRÍ further observations
  37. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  38. GRB 260120B: Fermi GBM Observation
  39. EP260105a: GTC/HiPERCAM optical observations
  40. GRB 260120B: Swift/UVOT Detection
  41. GRB 260120B: COLIBRÍ optical upper limits
  42. SVOM GRB260121.06: Global MASTER-Net observations report
  43. GRB 260120B: Enhanced Swift-XRT position
  44. GRB 260120B: SVOM/C-GFT optical counterpart detection
  45. GRB 260120C: Fermi GBM Final Real-time Localization
  46. GRB 260101A: 239Alferov CubeSat detection
  47. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  48. GRB 260120B: Swift detection of a burst
  49. GRB 260120B: Fermi GBM Final Real-time Localization
  50. EP260119A: Mondy I-Band Observations
  51. GRB 260114A: Swift/UVOT Upper Limits
  52. EP260119a: Liverpool Telescope optical follow-up observations
  53. GRB 251202A: further radio observations with the VLA
  54. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  55. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  56. EP260119a: KAIT optical observations
  57. GRB 260120A: Fermi GBM Final Real-time Localization
  58. EP260119a: SVOM/VT optical observation
  59. EP260119a: update of EP-FXT follow-up observation
  60. EP260119a: NOT optical observations
  61. EP260119a: SAO RAS optical observations
  62. SVOM GRB260119.92: Global MASTER-Net observations report
  63. SVOM GRB260119.92: Global MASTER-Net observations report
  64. SVOM GRB260119.90: Global MASTER-Net observations report
  65. EP260116a: COLIBRÍ detection of a fading optical source
  66. GRB 251208D: SVOM/ECLAIRs refined analysis
  67. GRB 251208D: SVOM/ECLAIRs refined analysis
  68. GRB 260117A: Swift-XRT afterglow detection
  69. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  70. GRB 260115A: AstroSat CZTI detection
  71. EP260119a: LCO optical observations
  72. GRB 260117A: ZTSh optical upper limit
  73. EP260119a: COLIBRÍ optical counterpart candidate
  74. EP260119a: preliminary result from the EP-FXT observation
  75. GRB 260110A: SVOM detection of a burst through offline search
  76. EP260119a: EP-WXT detection of a fast X-ray transient
  77. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  78. SVOM GRB260117.82: Global MASTER-Net observations report
  79. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  80. Swift trigger on the HMXB 1A 1118-61
  81. GRB 260117A: SVOM/VT optical candidate
  82. GRB 260117A: SVOM/C-GFT upper limit
  83. GRB 260117A: Swift-XRT observations
  84. GRB 260117A: Swift ToO observations
  85. GRB 260117A: SVOM detection of a long faint burst
  86. EP 260116a: COLIBRÍ optical upper limit
  87. Swift triggered on the HMXB 1A 1118-61
  88. GRB 260115A: GECAM-B observation
  89. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  90. EP260116a: Liverpool Telescope upper limits
  91. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  92. EP260116A: 1.3m DFOT optical upper limit
  93. GRB 260114A: VLT/MUSE spectroscopic observations
  94. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  95. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  96. EP260116a: Einstein Probe detection of an X-ray transient
  97. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  98. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  100. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka

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