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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"

41709 results found.

  1. EP260119a: SAO RAS optical observations
  2. SVOM GRB260119.92: Global MASTER-Net observations report
  3. SVOM GRB260119.92: Global MASTER-Net observations report
  4. SVOM GRB260119.90: Global MASTER-Net observations report
  5. EP260116a: COLIBRÍ detection of a fading optical source
  6. GRB 251208D: SVOM/ECLAIRs refined analysis
  7. GRB 251208D: SVOM/ECLAIRs refined analysis
  8. GRB 260117A: Swift-XRT afterglow detection
  9. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  10. EP260119a: Global MASTER-Net observations report
  11. GRB 260115A: AstroSat CZTI detection
  12. EP260119a: LCO optical observations
  13. GRB 260117A: ZTSh optical upper limit
  14. EP260119a: COLIBRÍ optical counterpart candidate
  15. EP260119a: preliminary result from the EP-FXT observation
  16. GRB 260110A: SVOM detection of a burst through offline search
  17. EP260119a: EP-WXT detection of a fast X-ray transient
  18. Swift GRB260118.48: Global MASTER-Net observations report
  19. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  20. SVOM GRB260117.82: Global MASTER-Net observations report
  21. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  22. Swift trigger on the HMXB 1A 1118-61
  23. GRB 260117A: SVOM/VT optical candidate
  24. GRB 260117A: SVOM/C-GFT upper limit
  25. GRB 260117A: Swift-XRT observations
  26. GRB 260117A: Swift ToO observations
  27. GRB 260117A: SVOM detection of a long faint burst
  28. EP 260116a: COLIBRÍ optical upper limit
  29. Swift triggered on the HMXB 1A 1118-61
  30. GRB 260115A: GECAM-B observation
  31. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  32. EP260116a: Liverpool Telescope upper limits
  33. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  34. EP260116A: 1.3m DFOT optical upper limit
  35. GRB 260114A: VLT/MUSE spectroscopic observations
  36. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  37. EP260116a: Global MASTER-Net observations report
  38. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  39. EP260116a: Einstein Probe detection of an X-ray transient
  40. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  41. IceCube Alert 260115.73: Global MASTER-Net observations report
  42. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  44. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  45. Fermi GRB 260115A: Global MASTER-Net observations report
  46. GRB 260115A: Fermi GBM Final Real-time Localization
  47. GRB260114A: STEP/T80S optical limits
  48. GRB 251222A: radio detection with the VLA
  49. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  50. Konus-Wind detection of GRB 260114A
  51. GRB 260114A: Swift-XRT refined Analysis
  52. GRB 260114A: 6 GHz VLA observations
  53. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  54. GRB 260114A : MITSuME Akeno optical upper limits
  55. GRB 260114A: COLIBRÍ optical upper limits
  56. GRB 260114A: TNG NIR upper limit
  57. GRB 260114A: NOT optical observations
  58. Konus-Wind detection of GRB 251230A / EP251230a
  59. GRB 260114A: SVOM/GRM observation of a short burst
  60. Swift GRB 260114A: Global MASTER-Net observations report
  61. GRB 260114A: GECAM-B observation of a short burst
  62. GRB 260114A: Mondy optical observations
  63. GRB 260114A: Fermi GBM observation
  64. GRB 260112B: GECAM-B observation
  65. GRB 260114A: GMG Optical Observation
  66. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  67. GRB 260114A: Swift detection of a short burst
  68. GRB 260114A: Fermi GBM Final Real-time Localization
  69. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  70. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  71. Swift GRB260113.43: Global MASTER-Net observations report
  72. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  73. EP260110a: TRT optical upper limits
  74. Konus-Wind detection of GRB 260101A
  75. GRB 260111A: Swift-XRT observations
  76. Swift Trigger 1439093: is probably not GRB 260113A
  77. GRB 260111A: COLIBRÍ optical afterglow candidate
  78. GRB 260111A: GECAM-B observation of a burst
  79. GRB 260111A: Fermi GBM Observation
  80. The EP-WXT trigger 01709251266 is likely a flaring star
  81. GRB 260111A: GOTO optical upper limits
  82. GRB 260112B: Fermi GBM Final Real-time Localization
  83. GRB 260111A: Swift ToO observations
  84. GRB 251230A: Mondy Optical Observations
  85. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  86. GRB 260112A: Fermi GBM Final Real-time Localization
  87. EP260110a: SVOM/VT optical upper limits
  88. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  89. IceCube Alert 260111A: Global MASTER-Net observations report
  90. EP260110a: Global MASTER-Net observations report
  91. Fermi GRB 260111A: Global MASTER-Net observations report
  92. GRB 260111A: Fermi GBM Final Real-time Localization
  93. Swift trigger 1436759 is not an astrophysical event
  94. EP260110a: KAIT optical upper limit
  95. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  96. EP 260110a: COLIBRÍ optical observations
  97. EP260110a: SVOM/C-GFT upper limit
  98. EP260110a: BOOTES-5/JGU optical upper limit
  99. EP260110a: Einstein Probe detection of an X-ray transient
  100. GRB 260109C: LCO optical upper limits

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