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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"

28047 results found.

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

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