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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"

28042 results found.

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

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