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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"

45409 results found.

  1. The EP-WXT trigger 01709250617 is likely a flaring star
  2. IceCube Alert 251225.84: Global MASTER-Net observations report
  3. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  4. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  5. GRB 251222A: NUTTelA-TAO Early Measurements
  6. GRB 251222A/EP251222b: Optical detection with Kinder observations
  7. EP251222a: Optical upper limit with Kinder observations
  8. GRB 251221A: Swift-BAT refined analysis
  9. GRB 251222A/EP251222b: FTW optical and NIR observations
  10. EP251222a: FTW optical and NIR observations
  11. GRB 251205A: Kilonova-Catcher optical afterglow detection
  12. GRB 251222A: AbAO optical observations
  13. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  14. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  15. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  16. GRB 251222A: ZTSH BVRI optical observations
  17. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  18. GRB 251222A: Continued 1.3m DFOT optical observation
  19. EP251220a: 3.6m DOT optical afterglow detection
  20. GRB 251222A: Fermi GBM Observation
  21. EP251220a: CrAO ZTSh optical observations
  22. EP251221a: PRIME upper limit
  23. EP251222a: Global MASTER-Net observations report
  24. GRB 251222A / EP251222b: GECAM-B observation
  25. EP251221a: Liverpool Telescope upper limits
  26. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  27. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  28. Konus-Wind detection of GRB 251222A / EP251222b
  29. GRB 251222A: Swift-XRT afterglow detection
  30. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  31. EP251222a: NTT/ULTRACAM optical observations
  32. EP251222a: GOTO optical upper limit
  33. GRB 251222A / EP251222b: GOTO optical counterpart detection
  34. GRB 251222A / EP251222b: LCO optical observations
  35. GRB 251222A: 1.3m DFOT optical detection
  36. GRB251221A: 7DT optical upper limits
  37. EP251222a: GSP Optical Counterpart Detection
  38. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  39. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  40. EP251222b/GRB 251222A: SVOM/GRM observation
  41. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  42. EP251222a: Einstein Probe detection of an X-ray transient
  43. The EP-WXT trigger 01709250397 is likely a flaring star
  44. EP251221a: Global MASTER-Net observations report
  45. GRB 251222A: PRIME near-infrared detection
  46. EP251221a: NOT optical upper limit
  47. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  48. GRB 251222A: NOT optical observations
  49. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  50. IPN triangulation of GRB 251220B (short)
  51. GRB 251222A: Swift ToO observations
  52. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  53. GRB 251222A: SVOM/VT optical candidate
  54. GRB 251222A: SVOM detection of a long burst
  55. SVOM GRB251222A: Global MASTER-Net observations report
  56. GRB 251222A: Fermi GBM Final Real-time Localization
  57. EP251220a: PRIME upper limit
  58. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  59. GRB 251221A: PRIME near-infrared observation
  60. EP251220a: NOT optical observations
  61. EP251220a: FTW optical and NIR observations
  62. GRB 251221A: UAFO and Mondy optical upper limit
  63. GRB 251221A: Swift-XRT refined Analysis
  64. EP251221a: Einstein Probe detection of a fast X-ray transient
  65. GRB 251221A: Swift/UVOT Upper Limits
  66. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  67. GRB 251221A: Enhanced Swift-XRT position
  68. GRB 251221A: Fermi GBM Observation
  69. GRB 251221B: Fermi GBM Final Real-time Localization
  70. EP251220a: EP-FXT follow-up observation
  71. GRB 251220B: SVOM/GRM observation of a short burst
  72. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  73. EP 251220a: GOTO optical counterpart detection
  74. GRB 251221A: COLIBRÍ detection of the optical counterpart
  75. EP 251220a: COLIBRÍ detection of the optical counterpart
  76. GRB 251221A: Swift detection of a burst
  77. Swift GRB251221A: Global MASTER-Net observations report
  78. GRB 251221A: Fermi GBM Final Real-time Localization
  79. EP251220a: Global MASTER-Net observations report
  80. EP251220a: EP detection of a fast X-ray transient
  81. SVOM GRB251220.98: Global MASTER-Net observations report
  82. GRB 251220B: Fermi GBM Final Real-time Localization
  83. GRB 251219A: SVOM/GRM observation of a short burst
  84. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  85. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  86. GRB 251220A: MAXI/GSC detection
  87. GRB 251215A: Swift-XRT afterglow detection
  88. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  89. IceCube-251218A: COLIBRÍ optical upper limits
  90. SVOM GRB251219.11: Global MASTER-Net observations report
  91. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  92. IceCube Alert 251218.85: Global MASTER-Net observations report
  93. GRB 251214B: VIRT Optical Upper Limit
  94. Fermi trigger No 787736968: Global MASTER-Net observations report
  95. Fermi GRB 251217A: Global MASTER-Net observations report
  96. GRB 251217A: Fermi GBM Final Real-time Localization
  97. GRB 251215A: Swift/UVOT Upper LImits
  98. GRB 251215A: Fermi GBM Observation
  99. Fermi GRB 251216A: Global MASTER-Net observations report
  100. GRB 251202A/EP251202a: Koshka optical upper limit

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