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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"

28085 results found.

  1. EP260116a: COLIBRÍ detection of a fading optical source
  2. GRB 260117A: Swift-XRT afterglow detection
  3. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  4. EP260119a: Global MASTER-Net observations report
  5. EP260119a: LCO optical observations
  6. GRB 260117A: ZTSh optical upper limit
  7. EP260119a: COLIBRÍ optical counterpart candidate
  8. EP260119a: EP-WXT detection of a fast X-ray transient
  9. Swift GRB260118.48: Global MASTER-Net observations report
  10. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  11. SVOM GRB260117.82: Global MASTER-Net observations report
  12. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  13. Swift trigger on the HMXB 1A 1118-61
  14. GRB 260117A: SVOM/VT optical candidate
  15. GRB 260117A: SVOM/C-GFT upper limit
  16. GRB 260117A: Swift-XRT observations
  17. GRB 260117A: SVOM detection of a long faint burst
  18. EP 260116a: COLIBRÍ optical upper limit
  19. Swift triggered on the HMXB 1A 1118-61
  20. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  21. EP260116a: Liverpool Telescope upper limits
  22. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  23. EP260116A: 1.3m DFOT optical upper limit
  24. GRB 260114A: VLT/MUSE spectroscopic observations
  25. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  26. EP260116a: Global MASTER-Net observations report
  27. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  28. EP260116a: Xinglong optical upper limit
  29. EP260116a: Einstein Probe detection of an X-ray transient
  30. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  31. IceCube Alert 260115.73: Global MASTER-Net observations report
  32. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  33. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  34. Fermi GRB 260115A: Global MASTER-Net observations report
  35. GRB 251222A: radio detection with the VLA
  36. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  37. GRB 260114A: Swift-XRT refined Analysis
  38. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  39. GRB 260114A : MITSuME Akeno optical upper limits
  40. GRB 260114A: COLIBRÍ optical upper limits
  41. GRB 260114A: TNG NIR upper limit
  42. GRB 260114A: NOT optical observations
  43. GRB 260114A: SVOM/GRM observation of a short burst
  44. Swift GRB 260114A: Global MASTER-Net observations report
  45. GRB 260114A: Mondy optical observations
  46. GRB 260114A: GMG Optical Observation
  47. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  48. GRB 260114A: Swift detection of a short burst
  49. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  50. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  51. Swift GRB260113.43: Global MASTER-Net observations report
  52. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  53. EP260110a: TRT optical upper limits
  54. Konus-Wind detection of GRB 260101A
  55. GRB 260111A: Swift-XRT observations
  56. Swift Trigger 1439093: is probably not GRB 260113A
  57. GRB 260111A: COLIBRÍ optical afterglow candidate
  58. GRB 260111A: Fermi GBM Observation
  59. GRB 251230A: Mondy Optical Observations
  60. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  61. IceCube Alert 260111A: Global MASTER-Net observations report
  62. EP260110a: Global MASTER-Net observations report
  63. Fermi GRB 260111A: Global MASTER-Net observations report
  64. Swift trigger 1436759 is not an astrophysical event
  65. EP260110a: KAIT optical upper limit
  66. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  67. EP 260110a: COLIBRÍ optical observations
  68. EP260110a: SVOM/C-GFT upper limit
  69. EP260110a: Einstein Probe detection of an X-ray transient
  70. GRB 260109C: LCO optical upper limits
  71. GRB 260109C: Kilonova-Catcher optical upper limit
  72. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  73. Swift Trigger 1434591: possible GRB 260109C
  74. GRB 260102A: Swift-XRT afterglow detection
  75. GRB 260104A: Swift-BAT refined analysis
  76. GRB 260101A: Swift-BAT refined analysis
  77. Swift GRB 251230A: Global MASTER-Net OT detection
  78. Fermi GRB 260107A: Global MASTER-Net observations report
  79. GRB 260102A: AbAO optical observations
  80. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  81. Fermi GRB 260105A: Global MASTER-Net observations report
  82. GRB 260105B: Fermi GBM Detection
  83. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  84. GRB 260105A: SVOM/GRM observation
  85. GRB 260105B: SVOM/GRM observation
  86. FRB 20251229A: COLIBRÍ optical upper limits
  87. Fermi GRB 260105B: Global MASTER-Net observations report
  88. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  89. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  90. EP260105a: LCO Optical Upper limit
  91. EP260104a: Global MASTER-Net observations report
  92. EP260104a: Einstein Probe detection of a fast X-ray transient
  93. GRB 260101A: COLIBRÍ optical upper limits
  94. EP260105a: Global MASTER-Net observations report
  95. EP260105a: Einstein Probe detection of an X-ray transient
  96. GRB 260104A: COLIBRÍ optical upper limits
  97. Fermi GRB 260104B: Global MASTER-Net observations report
  98. Swift GRB 260104A: Global MASTER-Net observations report
  99. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  100. GRB 260104A: Swift-XRT refined Analysis

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