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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"

28081 results found.

  1. EP260119a: LCO optical observations
  2. GRB 260117A: ZTSh optical upper limit
  3. EP260119a: COLIBRÍ optical counterpart candidate
  4. EP260119a: EP-WXT detection of a fast X-ray transient
  5. Swift GRB260118.48: Global MASTER-Net observations report
  6. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  7. SVOM GRB260117.82: Global MASTER-Net observations report
  8. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  9. Swift trigger on the HMXB 1A 1118-61
  10. GRB 260117A: SVOM/VT optical candidate
  11. GRB 260117A: SVOM/C-GFT upper limit
  12. GRB 260117A: Swift-XRT observations
  13. GRB 260117A: SVOM detection of a long faint burst
  14. EP 260116a: COLIBRÍ optical upper limit
  15. Swift triggered on the HMXB 1A 1118-61
  16. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  17. EP260116a: Liverpool Telescope upper limits
  18. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  19. EP260116A: 1.3m DFOT optical upper limit
  20. GRB 260114A: VLT/MUSE spectroscopic observations
  21. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  22. EP260116a: Global MASTER-Net observations report
  23. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  24. EP260116a: Xinglong optical upper limit
  25. EP260116a: Einstein Probe detection of an X-ray transient
  26. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  27. IceCube Alert 260115.73: Global MASTER-Net observations report
  28. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  29. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  30. Fermi GRB 260115A: Global MASTER-Net observations report
  31. GRB 251222A: radio detection with the VLA
  32. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  33. GRB 260114A: Swift-XRT refined Analysis
  34. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  35. GRB 260114A : MITSuME Akeno optical upper limits
  36. GRB 260114A: COLIBRÍ optical upper limits
  37. GRB 260114A: TNG NIR upper limit
  38. GRB 260114A: NOT optical observations
  39. GRB 260114A: SVOM/GRM observation of a short burst
  40. Swift GRB 260114A: Global MASTER-Net observations report
  41. GRB 260114A: Mondy optical observations
  42. GRB 260114A: GMG Optical Observation
  43. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  44. GRB 260114A: Swift detection of a short burst
  45. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  46. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  47. Swift GRB260113.43: Global MASTER-Net observations report
  48. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  49. EP260110a: TRT optical upper limits
  50. Konus-Wind detection of GRB 260101A
  51. GRB 260111A: Swift-XRT observations
  52. Swift Trigger 1439093: is probably not GRB 260113A
  53. GRB 260111A: COLIBRÍ optical afterglow candidate
  54. GRB 260111A: Fermi GBM Observation
  55. GRB 251230A: Mondy Optical Observations
  56. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  57. IceCube Alert 260111A: Global MASTER-Net observations report
  58. EP260110a: Global MASTER-Net observations report
  59. Fermi GRB 260111A: Global MASTER-Net observations report
  60. Swift trigger 1436759 is not an astrophysical event
  61. EP260110a: KAIT optical upper limit
  62. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  63. EP 260110a: COLIBRÍ optical observations
  64. EP260110a: SVOM/C-GFT upper limit
  65. EP260110a: Einstein Probe detection of an X-ray transient
  66. GRB 260109C: LCO optical upper limits
  67. GRB 260109C: Kilonova-Catcher optical upper limit
  68. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  69. Swift Trigger 1434591: possible GRB 260109C
  70. GRB 260102A: Swift-XRT afterglow detection
  71. GRB 260104A: Swift-BAT refined analysis
  72. GRB 260101A: Swift-BAT refined analysis
  73. Swift GRB 251230A: Global MASTER-Net OT detection
  74. Fermi GRB 260107A: Global MASTER-Net observations report
  75. GRB 260102A: AbAO optical observations
  76. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  77. Fermi GRB 260105A: Global MASTER-Net observations report
  78. GRB 260105B: Fermi GBM Detection
  79. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  80. GRB 260105A: SVOM/GRM observation
  81. GRB 260105B: SVOM/GRM observation
  82. FRB 20251229A: COLIBRÍ optical upper limits
  83. Fermi GRB 260105B: Global MASTER-Net observations report
  84. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  85. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  86. EP260105a: LCO Optical Upper limit
  87. EP260104a: Global MASTER-Net observations report
  88. EP260104a: Einstein Probe detection of a fast X-ray transient
  89. GRB 260101A: COLIBRÍ optical upper limits
  90. EP260105a: Global MASTER-Net observations report
  91. EP260105a: Einstein Probe detection of an X-ray transient
  92. GRB 260104A: COLIBRÍ optical upper limits
  93. Fermi GRB 260104B: Global MASTER-Net observations report
  94. Swift GRB 260104A: Global MASTER-Net observations report
  95. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  96. GRB 260104A: Swift-XRT refined Analysis
  97. GRB 260104A: Enhanced Swift-XRT position
  98. GRB 260101A: Swift/UVOT Detection
  99. GRB 260103A: GECAM-B observation of a burst
  100. GRB 260104A: Swift detection of a burst

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