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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"

28090 results found.

  1. SVOM GRB260119.90: Global MASTER-Net observations report
  2. EP260116a: COLIBRÍ detection of a fading optical source
  3. GRB 260117A: Swift-XRT afterglow detection
  4. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  5. EP260119a: Global MASTER-Net observations report
  6. EP260119a: LCO optical observations
  7. GRB 260117A: ZTSh optical upper limit
  8. EP260119a: COLIBRÍ optical counterpart candidate
  9. EP260119a: EP-WXT detection of a fast X-ray transient
  10. Swift GRB260118.48: Global MASTER-Net observations report
  11. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  12. SVOM GRB260117.82: Global MASTER-Net observations report
  13. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  14. Swift trigger on the HMXB 1A 1118-61
  15. GRB 260117A: SVOM/VT optical candidate
  16. GRB 260117A: SVOM/C-GFT upper limit
  17. GRB 260117A: Swift-XRT observations
  18. GRB 260117A: SVOM detection of a long faint burst
  19. EP 260116a: COLIBRÍ optical upper limit
  20. Swift triggered on the HMXB 1A 1118-61
  21. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  22. EP260116a: Liverpool Telescope upper limits
  23. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  24. EP260116A: 1.3m DFOT optical upper limit
  25. GRB 260114A: VLT/MUSE spectroscopic observations
  26. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  27. EP260116a: Global MASTER-Net observations report
  28. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  29. EP260116a: Xinglong optical upper limit
  30. EP260116a: Einstein Probe detection of an X-ray transient
  31. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  32. IceCube Alert 260115.73: Global MASTER-Net observations report
  33. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  34. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  35. Fermi GRB 260115A: Global MASTER-Net observations report
  36. GRB 251222A: radio detection with the VLA
  37. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  38. GRB 260114A: Swift-XRT refined Analysis
  39. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  40. GRB 260114A : MITSuME Akeno optical upper limits
  41. GRB 260114A: COLIBRÍ optical upper limits
  42. GRB 260114A: TNG NIR upper limit
  43. GRB 260114A: NOT optical observations
  44. GRB 260114A: SVOM/GRM observation of a short burst
  45. Swift GRB 260114A: Global MASTER-Net observations report
  46. GRB 260114A: Mondy optical observations
  47. GRB 260114A: GMG Optical Observation
  48. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  49. GRB 260114A: Swift detection of a short burst
  50. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  51. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  52. Swift GRB260113.43: Global MASTER-Net observations report
  53. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  54. EP260110a: TRT optical upper limits
  55. Konus-Wind detection of GRB 260101A
  56. GRB 260111A: Swift-XRT observations
  57. Swift Trigger 1439093: is probably not GRB 260113A
  58. GRB 260111A: COLIBRÍ optical afterglow candidate
  59. GRB 260111A: Fermi GBM Observation
  60. GRB 251230A: Mondy Optical Observations
  61. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  62. IceCube Alert 260111A: Global MASTER-Net observations report
  63. EP260110a: Global MASTER-Net observations report
  64. Fermi GRB 260111A: Global MASTER-Net observations report
  65. Swift trigger 1436759 is not an astrophysical event
  66. EP260110a: KAIT optical upper limit
  67. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  68. EP 260110a: COLIBRÍ optical observations
  69. EP260110a: SVOM/C-GFT upper limit
  70. EP260110a: Einstein Probe detection of an X-ray transient
  71. GRB 260109C: LCO optical upper limits
  72. GRB 260109C: Kilonova-Catcher optical upper limit
  73. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  74. Swift Trigger 1434591: possible GRB 260109C
  75. GRB 260102A: Swift-XRT afterglow detection
  76. GRB 260104A: Swift-BAT refined analysis
  77. GRB 260101A: Swift-BAT refined analysis
  78. Swift GRB 251230A: Global MASTER-Net OT detection
  79. Fermi GRB 260107A: Global MASTER-Net observations report
  80. GRB 260102A: AbAO optical observations
  81. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  82. Fermi GRB 260105A: Global MASTER-Net observations report
  83. GRB 260105B: Fermi GBM Detection
  84. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  85. GRB 260105A: SVOM/GRM observation
  86. GRB 260105B: SVOM/GRM observation
  87. FRB 20251229A: COLIBRÍ optical upper limits
  88. Fermi GRB 260105B: Global MASTER-Net observations report
  89. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  90. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  91. EP260105a: LCO Optical Upper limit
  92. EP260104a: Global MASTER-Net observations report
  93. EP260104a: Einstein Probe detection of a fast X-ray transient
  94. GRB 260101A: COLIBRÍ optical upper limits
  95. EP260105a: Global MASTER-Net observations report
  96. EP260105a: Einstein Probe detection of an X-ray transient
  97. GRB 260104A: COLIBRÍ optical upper limits
  98. Fermi GRB 260104B: Global MASTER-Net observations report
  99. Swift GRB 260104A: Global MASTER-Net observations report
  100. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits

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