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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"

28037 results found.

  1. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  2. GRB 251226A: Glowbug gamma-ray detection
  3. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  4. Fermi GRB 251228A: Global MASTER-Net observations report
  5. GRB 251226A: SVOM/GRM observation
  6. GRB 251226A: GECAM-B detection
  7. SVOM GRB251227.07: Global MASTER-Net observations report
  8. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube Alert 251225.84: Global MASTER-Net observations report
  10. GRB 251222A/EP251222b: Optical detection with Kinder observations
  11. EP251222a: Optical upper limit with Kinder observations
  12. GRB 251221A: Swift-BAT refined analysis
  13. GRB 251205A: Kilonova-Catcher optical afterglow detection
  14. GRB 251222A: AbAO optical observations
  15. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  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. EP251221a: Liverpool Telescope upper limits
  25. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  26. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  27. GRB 251222A: Swift-XRT afterglow detection
  28. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  29. EP251222a: NTT/ULTRACAM optical observations
  30. GRB 251222A / EP251222b: GOTO optical counterpart detection
  31. GRB 251222A / EP251222b: LCO optical observations
  32. GRB 251222A: 1.3m DFOT optical detection
  33. GRB251221A: 7DT optical upper limits
  34. EP251222a: GSP Optical Counterpart Detection
  35. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  36. EP251222a: Einstein Probe detection of an X-ray transient
  37. EP251221a: Global MASTER-Net observations report
  38. GRB 251222A: PRIME near-infrared detection
  39. EP251221a: NOT optical upper limit
  40. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  41. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  42. IPN triangulation of GRB 251220B (short)
  43. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  44. GRB 251222A: SVOM/VT optical candidate
  45. GRB 251222A: SVOM detection of a long burst
  46. SVOM GRB251222A: Global MASTER-Net observations report
  47. EP251220a: PRIME upper limit
  48. GRB 251221A: PRIME near-infrared observation
  49. GRB 251221A: UAFO and Mondy optical upper limit
  50. GRB 251221A: Swift-XRT refined Analysis
  51. EP251221a: Einstein Probe detection of a fast X-ray transient
  52. GRB 251221A: Swift/UVOT Upper Limits
  53. GRB 251221A: Enhanced Swift-XRT position
  54. GRB 251221A: Fermi GBM Observation
  55. GRB 251220B: SVOM/GRM observation of a short burst
  56. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  57. EP 251220a: GOTO optical counterpart detection
  58. GRB 251221A: COLIBRÍ detection of the optical counterpart
  59. EP 251220a: COLIBRÍ detection of the optical counterpart
  60. GRB 251221A: Swift detection of a burst
  61. Swift GRB251221A: Global MASTER-Net observations report
  62. EP251220a: Global MASTER-Net observations report
  63. EP251220a: EP detection of a fast X-ray transient
  64. SVOM GRB251220.98: Global MASTER-Net observations report
  65. GRB 251219A: SVOM/GRM observation of a short burst
  66. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  67. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  68. GRB 251220A: MAXI/GSC detection
  69. GRB 251215A: Swift-XRT afterglow detection
  70. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  71. IceCube-251218A: COLIBRÍ optical upper limits
  72. SVOM GRB251219.11: Global MASTER-Net observations report
  73. IceCube Alert 251218.85: Global MASTER-Net observations report
  74. GRB 251214B: VIRT Optical Upper Limit
  75. Fermi trigger No 787736968: Global MASTER-Net observations report
  76. Fermi GRB 251217A: Global MASTER-Net observations report
  77. GRB 251215A: Swift/UVOT Upper LImits
  78. GRB 251215A: Fermi GBM Observation
  79. Fermi GRB 251216A: Global MASTER-Net observations report
  80. GRB 251202A/EP251202a: Koshka optical upper limit
  81. GRB 251214B: Mondy optical upper limit
  82. GRB 251215A: COLIBRÍ optical upper limit
  83. EP251214b: KAIT optical upper limit
  84. GRB 251215A: Swift-XRT observations
  85. Fermi GRB 251215A: Global MASTER-Net observations report
  86. EP251214a: Optical upper limit with Kinder observations
  87. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  88. GRB 251215A: Glowbug gamma-ray detection
  89. GRB 251214B: UAFO optical upper limit
  90. GRB 251214B: VLT/X-shooter observations
  91. GRB 251214B: Swift-BAT refined analysis
  92. GRB 251202A: radio detection with the VLA
  93. EP251214b: Global MASTER-Net observations report
  94. EP251214b : Einstein Probe detection of a fast X-ray transient
  95. EP251214b : Einstein Probe detection of a fast X-ray transient
  96. GRB 251214B: AbAO optical observations
  97. GRB 251214B: LCO detection of the optical counterpart
  98. GRB 251214B: Fermi GBM Observation
  99. EP251214b (EP trigger 01709250023): LCO optical limits
  100. GRB 251203B: AbAO optical observations

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