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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"

42434 results found.

  1. SVOM GRB251227.07: Global MASTER-Net observations report
  2. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  3. The EP-WXT trigger 01709250617 is likely a flaring star
  4. IceCube Alert 251225.84: Global MASTER-Net observations report
  5. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  6. GRB 251222A: NUTTelA-TAO Early Measurements
  7. GRB 251222A/EP251222b: Optical detection with Kinder observations
  8. EP251222a: Optical upper limit with Kinder observations
  9. GRB 251221A: Swift-BAT refined analysis
  10. GRB 251222A/EP251222b: FTW optical and NIR observations
  11. EP251222a: FTW optical and NIR observations
  12. GRB 251205A: Kilonova-Catcher optical afterglow detection
  13. GRB 251222A: AbAO optical observations
  14. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  15. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  16. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  17. GRB 251222A: ZTSH BVRI optical observations
  18. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. GRB 251222A: Continued 1.3m DFOT optical observation
  20. EP251220a: 3.6m DOT optical afterglow detection
  21. GRB 251222A: Fermi GBM Observation
  22. EP251220a: CrAO ZTSh optical observations
  23. EP251221a: PRIME upper limit
  24. EP251222a: Global MASTER-Net observations report
  25. GRB 251222A / EP251222b: GECAM-B observation
  26. EP251221a: Liverpool Telescope upper limits
  27. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  28. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  29. Konus-Wind detection of GRB 251222A / EP251222b
  30. GRB 251222A: Swift-XRT afterglow detection
  31. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  32. EP251222a: NTT/ULTRACAM optical observations
  33. EP251222a: GOTO optical upper limit
  34. GRB 251222A / EP251222b: GOTO optical counterpart detection
  35. GRB 251222A / EP251222b: LCO optical observations
  36. GRB 251222A: 1.3m DFOT optical detection
  37. GRB251221A: 7DT optical upper limits
  38. EP251222a: GSP Optical Counterpart Detection
  39. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  40. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  41. EP251222b/GRB 251222A: SVOM/GRM observation
  42. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  43. EP251222a: Einstein Probe detection of an X-ray transient
  44. The EP-WXT trigger 01709250397 is likely a flaring star
  45. EP251221a: Global MASTER-Net observations report
  46. GRB 251222A: PRIME near-infrared detection
  47. EP251221a: NOT optical upper limit
  48. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  49. GRB 251222A: NOT optical observations
  50. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  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. GRB 251221A: Enhanced Swift-XRT position
  67. GRB 251221A: Fermi GBM Observation
  68. GRB 251221B: Fermi GBM Final Real-time Localization
  69. EP251220a: EP-FXT follow-up observation
  70. GRB 251220B: SVOM/GRM observation of a short burst
  71. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  72. EP 251220a: GOTO optical counterpart detection
  73. GRB 251221A: COLIBRÍ detection of the optical counterpart
  74. EP 251220a: COLIBRÍ detection of the optical counterpart
  75. GRB 251221A: Swift detection of a burst
  76. Swift GRB251221A: Global MASTER-Net observations report
  77. GRB 251221A: Fermi GBM Final Real-time Localization
  78. EP251220a: Global MASTER-Net observations report
  79. EP251220a: EP detection of a fast X-ray transient
  80. SVOM GRB251220.98: Global MASTER-Net observations report
  81. GRB 251220B: Fermi GBM Final Real-time Localization
  82. GRB 251219A: SVOM/GRM observation of a short burst
  83. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  84. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  85. GRB 251220A: MAXI/GSC detection
  86. GRB 251215A: Swift-XRT afterglow detection
  87. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  88. IceCube-251218A: COLIBRÍ optical upper limits
  89. SVOM GRB251219.11: Global MASTER-Net observations report
  90. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  91. IceCube Alert 251218.85: Global MASTER-Net observations report
  92. GRB 251214B: VIRT Optical Upper Limit
  93. Fermi trigger No 787736968: Global MASTER-Net observations report
  94. Fermi GRB 251217A: Global MASTER-Net observations report
  95. GRB 251217A: Fermi GBM Final Real-time Localization
  96. GRB 251215A: Swift/UVOT Upper LImits
  97. GRB 251215A: Fermi GBM Observation
  98. Fermi GRB 251216A: Global MASTER-Net observations report
  99. GRB 251202A/EP251202a: Koshka optical upper limit
  100. GRB 251214B: Mondy optical upper limit

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