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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

41630 results found.

  1. GRB 260120B: COLIBRÍ optical upper limits
  2. SVOM GRB260121.06: Global MASTER-Net observations report
  3. GRB 260120B: Enhanced Swift-XRT position
  4. GRB 260120B: SVOM/C-GFT optical counterpart detection
  5. GRB 260120C: Fermi GBM Final Real-time Localization
  6. GRB 260101A: 239Alferov CubeSat detection
  7. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  8. GRB 260120B: Swift detection of a burst
  9. Swift GRB260120B: Global MASTER-Net observations report
  10. GRB 260120B: Fermi GBM Final Real-time Localization
  11. EP260119A: Mondy I-Band Observations
  12. Fermi trigger No 790601190: Global MASTER-Net observations report
  13. Fermi trigger No 790570272: Global MASTER-Net observations report
  14. GRB 260114A: Swift/UVOT Upper Limits
  15. EP260119a: Liverpool Telescope optical follow-up observations
  16. GRB 251202A: further radio observations with the VLA
  17. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  18. EP260119a: KAIT optical observations
  19. GRB 260120A: Fermi GBM Final Real-time Localization
  20. EP260119a: SVOM/VT optical observation
  21. EP260119a: update of EP-FXT follow-up observation
  22. EP260119a: NOT optical observations
  23. EP260119a: SAO RAS optical observations
  24. SVOM GRB260119.92: Global MASTER-Net observations report
  25. SVOM GRB260119.92: Global MASTER-Net observations report
  26. SVOM GRB260119.90: Global MASTER-Net observations report
  27. EP260116a: COLIBRÍ detection of a fading optical source
  28. GRB 251208D: SVOM/ECLAIRs refined analysis
  29. GRB 251208D: SVOM/ECLAIRs refined analysis
  30. GRB 260117A: Swift-XRT afterglow detection
  31. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  32. EP260119a: Global MASTER-Net observations report
  33. GRB 260115A: AstroSat CZTI detection
  34. EP260119a: LCO optical observations
  35. GRB 260117A: ZTSh optical upper limit
  36. EP260119a: COLIBRÍ optical counterpart candidate
  37. EP260119a: preliminary result from the EP-FXT observation
  38. GRB 260110A: SVOM detection of a burst through offline search
  39. EP260119a: EP-WXT detection of a fast X-ray transient
  40. Swift GRB260118.48: Global MASTER-Net observations report
  41. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  42. SVOM GRB260117.82: Global MASTER-Net observations report
  43. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  44. Swift trigger on the HMXB 1A 1118-61
  45. GRB 260117A: SVOM/VT optical candidate
  46. GRB 260117A: SVOM/C-GFT upper limit
  47. GRB 260117A: Swift-XRT observations
  48. GRB 260117A: Swift ToO observations
  49. GRB 260117A: SVOM detection of a long faint burst
  50. EP 260116a: COLIBRÍ optical upper limit
  51. Swift triggered on the HMXB 1A 1118-61
  52. GRB 260115A: GECAM-B observation
  53. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  54. EP260116a: Liverpool Telescope upper limits
  55. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  56. EP260116A: 1.3m DFOT optical upper limit
  57. GRB 260114A: VLT/MUSE spectroscopic observations
  58. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  59. EP260116a: Global MASTER-Net observations report
  60. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  61. EP260116a: Xinglong optical upper limit
  62. EP260116a: Einstein Probe detection of an X-ray transient
  63. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  64. IceCube Alert 260115.73: Global MASTER-Net observations report
  65. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  66. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  67. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  68. Fermi GRB 260115A: Global MASTER-Net observations report
  69. GRB 260115A: Fermi GBM Final Real-time Localization
  70. GRB260114A: STEP/T80S optical limits
  71. GRB 251222A: radio detection with the VLA
  72. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  73. Konus-Wind detection of GRB 260114A
  74. GRB 260114A: Swift-XRT refined Analysis
  75. GRB 260114A: 6 GHz VLA observations
  76. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  77. GRB 260114A : MITSuME Akeno optical upper limits
  78. GRB 260114A: COLIBRÍ optical upper limits
  79. GRB 260114A: TNG NIR upper limit
  80. GRB 260114A: NOT optical observations
  81. Konus-Wind detection of GRB 251230A / EP251230a
  82. GRB 260114A: SVOM/GRM observation of a short burst
  83. Swift GRB 260114A: Global MASTER-Net observations report
  84. GRB 260114A: GECAM-B observation of a short burst
  85. GRB 260114A: Mondy optical observations
  86. GRB 260114A: Fermi GBM observation
  87. GRB 260112B: GECAM-B observation
  88. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  89. GRB 260114A: Swift detection of a short burst
  90. GRB 260114A: Fermi GBM Final Real-time Localization
  91. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  92. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  93. Swift GRB260113.43: Global MASTER-Net observations report
  94. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  95. EP260110a: TRT optical upper limits
  96. Konus-Wind detection of GRB 260101A
  97. GRB 260111A: Swift-XRT observations
  98. Swift Trigger 1439093: is probably not GRB 260113A
  99. GRB 260111A: COLIBRÍ optical afterglow candidate
  100. GRB 260111A: GECAM-B observation of a burst

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