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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.

Advanced Search Examples (click to copy):

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

41198 results found.

  1. GRB 260125A: Fermi GBM Final Real-time Localization
  2. GRB 260114A: SVOM/VT optical upper limits
  3. GRB 260120A: AstroSat CZTI detection
  4. GRB 260122B: Swift-BAT refined analysis
  5. GRB 260120B: SVOM/GRM observation
  6. GRB 260120A: GECAM-B observation
  7. GRB 260120B: AstroSat CZTI detection
  8. GRB 260114A: Insight-HXMT/HE detection
  9. GRB 260122B: Swift detection of a burst
  10. Swift GRB260122.97: Global MASTER-Net observations report
  11. EP260119a: Assy AZT-20 optical observations
  12. EP260119a: Mondy and SAO RAS optical upper limits
  13. GRB 260122A: Fermi GBM Final Real-time Localization
  14. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  15. EP260119a: Xinglong optical upper limit
  16. The EP-WXT trigger 01709251871 is likely a flaring star
  17. Fermi GRB 260120C: Global MASTER-Net observations report
  18. GRB 260120B: Swift-BAT refined analysis
  19. GRB 260120B: Swift-XRT refined Analysis
  20. EP260116a: COLIBRÍ further observations
  21. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  22. GRB 260120B: Fermi GBM Observation
  23. EP260105a: GTC/HiPERCAM optical observations
  24. GRB 260120B: Swift/UVOT Detection
  25. GRB 260120B: COLIBRÍ optical upper limits
  26. SVOM GRB260121.06: Global MASTER-Net observations report
  27. GRB 260120B: Enhanced Swift-XRT position
  28. GRB 260120B: SVOM/C-GFT optical counterpart detection
  29. GRB 260120C: Fermi GBM Final Real-time Localization
  30. GRB 260101A: 239Alferov CubeSat detection
  31. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  32. GRB 260120B: Swift detection of a burst
  33. Swift GRB260120B: Global MASTER-Net observations report
  34. GRB 260120B: Fermi GBM Final Real-time Localization
  35. EP260119A: Mondy I-Band Observations
  36. Fermi trigger No 790601190: Global MASTER-Net observations report
  37. Fermi trigger No 790570272: Global MASTER-Net observations report
  38. GRB 260114A: Swift/UVOT Upper Limits
  39. EP260119a: Liverpool Telescope optical follow-up observations
  40. GRB 251202A: further radio observations with the VLA
  41. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  42. EP260119a: KAIT optical observations
  43. GRB 260120A: Fermi GBM Final Real-time Localization
  44. EP260119a: SVOM/VT optical observation
  45. EP260119a: update of EP-FXT follow-up observation
  46. EP260119a: NOT optical observations
  47. EP260119a: SAO RAS optical observations
  48. SVOM GRB260119.92: Global MASTER-Net observations report
  49. SVOM GRB260119.92: Global MASTER-Net observations report
  50. SVOM GRB260119.90: Global MASTER-Net observations report
  51. EP260116a: COLIBRÍ detection of a fading optical source
  52. GRB 251208D: SVOM/ECLAIRs refined analysis
  53. GRB 251208D: SVOM/ECLAIRs refined analysis
  54. GRB 260117A: Swift-XRT afterglow detection
  55. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  56. EP260119a: Global MASTER-Net observations report
  57. GRB 260115A: AstroSat CZTI detection
  58. EP260119a: LCO optical observations
  59. GRB 260117A: ZTSh optical upper limit
  60. EP260119a: COLIBRÍ optical counterpart candidate
  61. EP260119a: preliminary result from the EP-FXT observation
  62. GRB 260110A: SVOM detection of a burst through offline search
  63. EP260119a: EP-WXT detection of a fast X-ray transient
  64. Swift GRB260118.48: Global MASTER-Net observations report
  65. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  66. SVOM GRB260117.82: Global MASTER-Net observations report
  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-XRT observations
  72. GRB 260117A: Swift ToO observations
  73. GRB 260117A: SVOM detection of a long faint burst
  74. EP 260116a: COLIBRÍ optical upper limit
  75. Swift triggered on the HMXB 1A 1118-61
  76. GRB 260115A: GECAM-B observation
  77. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  78. EP260116a: Liverpool Telescope upper limits
  79. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  80. EP260116A: 1.3m DFOT optical upper limit
  81. GRB 260114A: VLT/MUSE spectroscopic observations
  82. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  83. EP260116a: Global MASTER-Net observations report
  84. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  85. EP260116a: Xinglong optical upper limit
  86. EP260116a: Einstein Probe detection of an X-ray transient
  87. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  88. IceCube Alert 260115.73: Global MASTER-Net observations report
  89. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  91. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  92. Fermi GRB 260115A: Global MASTER-Net observations report
  93. GRB 260115A: Fermi GBM Final Real-time Localization
  94. GRB260114A: STEP/T80S optical limits
  95. GRB 251222A: radio detection with the VLA
  96. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  97. Konus-Wind detection of GRB 260114A
  98. GRB 260114A: Swift-XRT refined Analysis
  99. GRB 260114A: 6 GHz VLA observations
  100. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy

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