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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"

26897 results found.

  1. Fermi trigger No 790570272: Global MASTER-Net observations report
  2. GRB 260114A: Swift/UVOT Upper Limits
  3. EP260119a: Liverpool Telescope optical follow-up observations
  4. GRB 251202A: further radio observations with the VLA
  5. EP260119a: KAIT optical observations
  6. EP260119a: SVOM/VT optical observation
  7. EP260119a: NOT optical observations
  8. EP260119a: SAO RAS optical observations
  9. SVOM GRB260119.92: Global MASTER-Net observations report
  10. SVOM GRB260119.92: Global MASTER-Net observations report
  11. SVOM GRB260119.90: Global MASTER-Net observations report
  12. EP260116a: COLIBRÍ detection of a fading optical source
  13. GRB 260117A: Swift-XRT afterglow detection
  14. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  15. EP260119a: Global MASTER-Net observations report
  16. EP260119a: LCO optical observations
  17. GRB 260117A: ZTSh optical upper limit
  18. EP260119a: COLIBRÍ optical counterpart candidate
  19. EP260119a: EP-WXT detection of a fast X-ray transient
  20. Swift GRB260118.48: Global MASTER-Net observations report
  21. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  22. SVOM GRB260117.82: Global MASTER-Net observations report
  23. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  24. Swift trigger on the HMXB 1A 1118-61
  25. GRB 260117A: SVOM/VT optical candidate
  26. GRB 260117A: SVOM/C-GFT upper limit
  27. GRB 260117A: Swift-XRT observations
  28. GRB 260117A: SVOM detection of a long faint burst
  29. EP 260116a: COLIBRÍ optical upper limit
  30. Swift triggered on the HMXB 1A 1118-61
  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: Xinglong optical upper limit
  40. EP260116a: Einstein Probe detection of an X-ray transient
  41. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  42. IceCube Alert 260115.73: Global MASTER-Net observations report
  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 251222A: radio detection with the VLA
  47. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  48. GRB 260114A: Swift-XRT refined Analysis
  49. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  50. GRB 260114A : MITSuME Akeno optical upper limits
  51. GRB 260114A: COLIBRÍ optical upper limits
  52. GRB 260114A: TNG NIR upper limit
  53. GRB 260114A: NOT optical observations
  54. GRB 260114A: SVOM/GRM observation of a short burst
  55. Swift GRB 260114A: Global MASTER-Net observations report
  56. GRB 260114A: Mondy optical observations
  57. GRB 260114A: GMG Optical Observation
  58. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  59. GRB 260114A: Swift detection of a short burst
  60. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  61. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  62. Swift GRB260113.43: Global MASTER-Net observations report
  63. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  64. EP260110a: TRT optical upper limits
  65. Konus-Wind detection of GRB 260101A
  66. GRB 260111A: Swift-XRT observations
  67. Swift Trigger 1439093: is probably not GRB 260113A
  68. GRB 260111A: COLIBRÍ optical afterglow candidate
  69. GRB 260111A: Fermi GBM Observation
  70. GRB 251230A: Mondy Optical Observations
  71. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  72. IceCube Alert 260111A: Global MASTER-Net observations report
  73. EP260110a: Global MASTER-Net observations report
  74. Fermi GRB 260111A: Global MASTER-Net observations report
  75. Swift trigger 1436759 is not an astrophysical event
  76. EP260110a: KAIT optical upper limit
  77. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  78. EP 260110a: COLIBRÍ optical observations
  79. EP260110a: SVOM/C-GFT upper limit
  80. EP260110a: Einstein Probe detection of an X-ray transient
  81. GRB 260109C: LCO optical upper limits
  82. GRB 260109C: Kilonova-Catcher optical upper limit
  83. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  84. Swift Trigger 1434591: possible GRB 260109C
  85. GRB 260102A: Swift-XRT afterglow detection
  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. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  92. Fermi GRB 260105A: Global MASTER-Net observations report
  93. GRB 260105B: Fermi GBM Detection
  94. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  95. GRB 260105A: SVOM/GRM observation
  96. GRB 260105B: SVOM/GRM observation
  97. FRB 20251229A: COLIBRÍ optical upper limits
  98. Fermi GRB 260105B: Global MASTER-Net observations report
  99. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  100. EP260105a: refined analysis of the EP-WXT and EP-FXT observations

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