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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

45558 results found.

  1. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  2. GRB 260120B: Swift detection of a burst
  3. Swift GRB260120B: Global MASTER-Net observations report
  4. GRB 260120B: Fermi GBM Final Real-time Localization
  5. EP260119A: Mondy I-Band Observations
  6. Fermi trigger No 790601190: Global MASTER-Net observations report
  7. Fermi trigger No 790570272: Global MASTER-Net observations report
  8. GRB 260114A: Swift/UVOT Upper Limits
  9. EP260119a: Liverpool Telescope optical follow-up observations
  10. GRB 251202A: further radio observations with the VLA
  11. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  12. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  13. EP260119a: KAIT optical observations
  14. GRB 260120A: Fermi GBM Final Real-time Localization
  15. EP260119a: SVOM/VT optical observation
  16. EP260119a: update of EP-FXT follow-up observation
  17. EP260119a: NOT optical observations
  18. EP260119a: SAO RAS optical observations
  19. SVOM GRB260119.92: Global MASTER-Net observations report
  20. SVOM GRB260119.92: Global MASTER-Net observations report
  21. SVOM GRB260119.90: Global MASTER-Net observations report
  22. EP260116a: COLIBRÍ detection of a fading optical source
  23. GRB 251208D: SVOM/ECLAIRs refined analysis
  24. GRB 251208D: SVOM/ECLAIRs refined analysis
  25. GRB 260117A: Swift-XRT afterglow detection
  26. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  27. EP260119a: Global MASTER-Net observations report
  28. GRB 260115A: AstroSat CZTI detection
  29. EP260119a: LCO optical observations
  30. GRB 260117A: ZTSh optical upper limit
  31. EP260119a: COLIBRÍ optical counterpart candidate
  32. EP260119a: preliminary result from the EP-FXT observation
  33. GRB 260110A: SVOM detection of a burst through offline search
  34. EP260119a: EP-WXT detection of a fast X-ray transient
  35. Swift GRB260118.48: Global MASTER-Net observations report
  36. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. SVOM GRB260117.82: Global MASTER-Net observations report
  38. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  39. Swift trigger on the HMXB 1A 1118-61
  40. GRB 260117A: SVOM/VT optical candidate
  41. GRB 260117A: SVOM/C-GFT upper limit
  42. GRB 260117A: Swift-XRT observations
  43. GRB 260117A: Swift ToO observations
  44. GRB 260117A: SVOM detection of a long faint burst
  45. EP 260116a: COLIBRÍ optical upper limit
  46. Swift triggered on the HMXB 1A 1118-61
  47. GRB 260115A: GECAM-B observation
  48. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  49. EP260116a: Liverpool Telescope upper limits
  50. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  51. EP260116A: 1.3m DFOT optical upper limit
  52. GRB 260114A: VLT/MUSE spectroscopic observations
  53. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  54. EP260116a: Global MASTER-Net observations report
  55. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  56. EP260116a: Xinglong optical upper limit
  57. EP260116a: Einstein Probe detection of an X-ray transient
  58. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  59. IceCube Alert 260115.73: Global MASTER-Net observations report
  60. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  62. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  63. Fermi GRB 260115A: Global MASTER-Net observations report
  64. GRB 260115A: Fermi GBM Final Real-time Localization
  65. GRB260114A: STEP/T80S optical limits
  66. GRB 251222A: radio detection with the VLA
  67. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  68. Konus-Wind detection of GRB 260114A
  69. GRB 260114A: Swift-XRT refined Analysis
  70. GRB 260114A: 6 GHz VLA observations
  71. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  72. GRB 260114A : MITSuME Akeno optical upper limits
  73. GRB 260114A: COLIBRÍ optical upper limits
  74. GRB 260114A: TNG NIR upper limit
  75. GRB 260114A: NOT optical observations
  76. Konus-Wind detection of GRB 251230A / EP251230a
  77. GRB 260114A: SVOM/GRM observation of a short burst
  78. Swift GRB 260114A: Global MASTER-Net observations report
  79. GRB 260114A: GECAM-B observation of a short burst
  80. GRB 260114A: Mondy optical observations
  81. GRB 260114A: Fermi GBM observation
  82. GRB 260112B: GECAM-B observation
  83. GRB 260114A: GMG Optical Observation
  84. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  85. GRB 260114A: Swift detection of a short burst
  86. GRB 260114A: Fermi GBM Final Real-time Localization
  87. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  88. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  89. Swift GRB260113.43: Global MASTER-Net observations report
  90. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  91. EP260110a: TRT optical upper limits
  92. Konus-Wind detection of GRB 260101A
  93. GRB 260111A: Swift-XRT observations
  94. Swift Trigger 1439093: is probably not GRB 260113A
  95. GRB 260111A: COLIBRÍ optical afterglow candidate
  96. GRB 260111A: GECAM-B observation of a burst
  97. GRB 260111A: Fermi GBM Observation
  98. The EP-WXT trigger 01709251266 is likely a flaring star
  99. Swift Trigger 1434591 is not a GRB
  100. GRB 260111A: GOTO optical upper limits

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