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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"

28051 results found.

  1. EP260128a: NOT optical counterpart candidate
  2. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  3. EP260128a: Liverpool Telescope optical observations and possible counterpart
  4. EP260128a: LCO optical upper limits
  5. EP260128a: Global MASTER-Net observations report
  6. EP260128a: Einstein Probe detection of an X-ray transient
  7. Fermi GRB 260127A: Global MASTER-Net observations report
  8. GRB 260127A: Fermi GBM Observation
  9. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 260127A: COLIBRÍ optical observations
  11. EP260126a: Seimei/TriCCS optical upper limit
  12. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  13. GRB 260127A: Swift-XRT refined Analysis
  14. GRB 260127A: SVOM/C-GFT optical observations
  15. GRB 260127A: Enhanced Swift-XRT position
  16. Fermi GRB 260127B: Global MASTER-Net observations report
  17. Swift GRB 260127A: Global MASTER-Net observations report
  18. GRB 260127A: LCO optical afterglow discovery
  19. GRB 260127A: Swift detection of a burst
  20. GRB 260125A: Swift-XRT observations
  21. EP260126a: Optical upper limit with Kinder observations
  22. EP260126a: Liverpool Telescope optical upper limits
  23. EP260126a: Further NOT optical upper limits
  24. EP260126a: COLIBRÍ optical upper limits
  25. EP260126a: NOT optical observations
  26. EP260126a: Einstein Probe detection of a fast X-ray transient
  27. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  28. GRB 251222A: SVOM/ECLAIRs refined analysis
  29. GRB 260125A: GOTO candidate optical counterpart
  30. Fermi GRB 260125B: Global MASTER-Net observations report
  31. GRB 260114A: SVOM/VT optical upper limits
  32. GRB 260122B: Swift-BAT refined analysis
  33. GRB 260120B: SVOM/GRM observation
  34. Swift GRB260122.97: Global MASTER-Net observations report
  35. EP260119a: Assy AZT-20 optical observations
  36. EP260119a: Mondy and SAO RAS optical upper limits
  37. EP260119a: Xinglong optical upper limit
  38. Fermi GRB 260120C: Global MASTER-Net observations report
  39. GRB 260120B: Swift-BAT refined analysis
  40. GRB 260120B: Swift-XRT refined Analysis
  41. EP260116a: COLIBRÍ further observations
  42. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  43. GRB 260120B: Fermi GBM Observation
  44. EP260105a: GTC/HiPERCAM optical observations
  45. GRB 260120B: Swift/UVOT Detection
  46. GRB 260120B: COLIBRÍ optical upper limits
  47. SVOM GRB260121.06: Global MASTER-Net observations report
  48. GRB 260120B: Enhanced Swift-XRT position
  49. GRB 260120B: SVOM/C-GFT optical counterpart detection
  50. GRB 260101A: 239Alferov CubeSat detection
  51. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  52. GRB 260120B: Swift detection of a burst
  53. Swift GRB260120B: Global MASTER-Net observations report
  54. EP260119A: Mondy I-Band Observations
  55. Fermi trigger No 790601190: Global MASTER-Net observations report
  56. Fermi trigger No 790570272: Global MASTER-Net observations report
  57. GRB 260114A: Swift/UVOT Upper Limits
  58. EP260119a: Liverpool Telescope optical follow-up observations
  59. GRB 251202A: further radio observations with the VLA
  60. EP260119a: KAIT optical observations
  61. EP260119a: SVOM/VT optical observation
  62. EP260119a: NOT optical observations
  63. EP260119a: SAO RAS optical observations
  64. SVOM GRB260119.92: Global MASTER-Net observations report
  65. SVOM GRB260119.92: Global MASTER-Net observations report
  66. SVOM GRB260119.90: Global MASTER-Net observations report
  67. EP260116a: COLIBRÍ detection of a fading optical source
  68. GRB 260117A: Swift-XRT afterglow detection
  69. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  70. EP260119a: Global MASTER-Net observations report
  71. EP260119a: LCO optical observations
  72. GRB 260117A: ZTSh optical upper limit
  73. EP260119a: COLIBRÍ optical counterpart candidate
  74. EP260119a: EP-WXT detection of a fast X-ray transient
  75. Swift GRB260118.48: Global MASTER-Net observations report
  76. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  77. SVOM GRB260117.82: Global MASTER-Net observations report
  78. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  79. Swift trigger on the HMXB 1A 1118-61
  80. GRB 260117A: SVOM/VT optical candidate
  81. GRB 260117A: SVOM/C-GFT upper limit
  82. GRB 260117A: Swift-XRT observations
  83. GRB 260117A: SVOM detection of a long faint burst
  84. EP 260116a: COLIBRÍ optical upper limit
  85. Swift triggered on the HMXB 1A 1118-61
  86. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  87. EP260116a: Liverpool Telescope upper limits
  88. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  89. EP260116A: 1.3m DFOT optical upper limit
  90. GRB 260114A: VLT/MUSE spectroscopic observations
  91. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  92. EP260116a: Global MASTER-Net observations report
  93. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  94. EP260116a: Xinglong optical upper limit
  95. EP260116a: Einstein Probe detection of an X-ray transient
  96. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  97. IceCube Alert 260115.73: Global MASTER-Net observations report
  98. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  99. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  100. Fermi GRB 260115A: Global MASTER-Net observations report

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