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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"

44618 results found.

  1. GRB 260117A: SVOM/C-GFT upper limit
  2. GRB 260117A: Swift-XRT observations
  3. GRB 260117A: Swift ToO observations
  4. GRB 260117A: SVOM detection of a long faint burst
  5. EP 260116a: COLIBRÍ optical upper limit
  6. Swift triggered on the HMXB 1A 1118-61
  7. GRB 260115A: GECAM-B observation
  8. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  9. EP260116a: Liverpool Telescope upper limits
  10. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  11. EP260116A: 1.3m DFOT optical upper limit
  12. GRB 260114A: VLT/MUSE spectroscopic observations
  13. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  14. EP260116a: Global MASTER-Net observations report
  15. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  16. EP260116a: Xinglong optical upper limit
  17. EP260116a: Einstein Probe detection of an X-ray transient
  18. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  19. IceCube Alert 260115.73: Global MASTER-Net observations report
  20. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  22. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  23. Fermi GRB 260115A: Global MASTER-Net observations report
  24. GRB 260115A: Fermi GBM Final Real-time Localization
  25. GRB260114A: STEP/T80S optical limits
  26. GRB 251222A: radio detection with the VLA
  27. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  28. Konus-Wind detection of GRB 260114A
  29. GRB 260114A: Swift-XRT refined Analysis
  30. GRB 260114A: 6 GHz VLA observations
  31. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  32. GRB 260114A : MITSuME Akeno optical upper limits
  33. GRB 260114A: COLIBRÍ optical upper limits
  34. GRB 260114A: TNG NIR upper limit
  35. GRB 260114A: NOT optical observations
  36. Konus-Wind detection of GRB 251230A / EP251230a
  37. GRB 260114A: SVOM/GRM observation of a short burst
  38. Swift GRB 260114A: Global MASTER-Net observations report
  39. GRB 260114A: GECAM-B observation of a short burst
  40. GRB 260114A: Mondy optical observations
  41. GRB 260114A: Fermi GBM observation
  42. GRB 260112B: GECAM-B observation
  43. GRB 260114A: GMG Optical Observation
  44. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  45. GRB 260114A: Swift detection of a short burst
  46. GRB 260114A: Fermi GBM Final Real-time Localization
  47. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  48. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  49. Swift GRB260113.43: Global MASTER-Net observations report
  50. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  51. EP260110a: TRT optical upper limits
  52. Konus-Wind detection of GRB 260101A
  53. GRB 260111A: Swift-XRT observations
  54. Swift Trigger 1439093: is probably not GRB 260113A
  55. GRB 260111A: COLIBRÍ optical afterglow candidate
  56. GRB 260111A: GECAM-B observation of a burst
  57. GRB 260111A: Fermi GBM Observation
  58. The EP-WXT trigger 01709251266 is likely a flaring star
  59. Swift Trigger 1434591 is not a GRB
  60. GRB 260111A: GOTO optical upper limits
  61. GRB 260112B: Fermi GBM Final Real-time Localization
  62. GRB 260111A: Swift ToO observations
  63. GRB 251230A: Mondy Optical Observations
  64. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  65. GRB 260112A: Fermi GBM Final Real-time Localization
  66. EP260110a: SVOM/VT optical upper limits
  67. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube Alert 260111A: Global MASTER-Net observations report
  69. EP260110a: Global MASTER-Net observations report
  70. Fermi GRB 260111A: Global MASTER-Net observations report
  71. GRB 260111A: Fermi GBM Final Real-time Localization
  72. Swift trigger 1436759 is not an astrophysical event
  73. EP260110a: KAIT optical upper limit
  74. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  75. EP 260110a: COLIBRÍ optical observations
  76. EP260110a: SVOM/C-GFT upper limit
  77. EP260110a: BOOTES-5/JGU optical upper limit
  78. EP260110a: Einstein Probe detection of an X-ray transient
  79. GRB 260109C: LCO optical upper limits
  80. GRB 260109C: Kilonova-Catcher optical upper limit
  81. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  82. Swift Trigger 1434591: possible GRB 260109C
  83. GRB 260109B: Fermi GBM Final Real-time Localization
  84. GRB 260102A: Swift-XRT afterglow detection
  85. GRB 260109A: Fermi GBM Final Real-time Localization
  86. GRB 260104A: Swift-BAT refined analysis
  87. GRB 260101A: Swift-BAT refined analysis
  88. Swift GRB 251230A: Global MASTER-Net OT detection
  89. Fermi GRB 260107A: Global MASTER-Net observations report
  90. GRB 260102A: AbAO optical observations
  91. GRB 260107A: Fermi GBM Final Real-time Localization
  92. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  93. The EP-WXT trigger 01709251112 is likely a flaring star
  94. Fermi GRB 260105A: Global MASTER-Net observations report
  95. GRB 260105B: Fermi GBM Detection
  96. EP260105a: FTW optical observations
  97. EP260104a: FTW optical observations
  98. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  99. GRB 260105A: SVOM/GRM observation
  100. GRB 260105B: SVOM/GRM observation

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