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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"

2976 results found.

  1. GRB 260303A: SVOM/ECLAIRs refined analysis
  2. Fermi GRB 260305A: Global MASTER-Net observations report
  3. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  4. GRB 260303A: SVOM detection of a burst
  5. GRB 260302A: Fermi GBM Final Real-time Localization
  6. EP260227a: Mephisto optical detection
  7. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  8. Fermi GRB 260226A: Global MASTER-Net observations report
  9. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  10. Fermi GRB 260221B: Global MASTER-Net observations report
  11. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  12. Fermi GRB 260219A: Global MASTER-Net observations report
  13. IPN triangulation of GRB 260212A
  14. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  15. GRB 260204A: SVOM/ECLAIRs refined analysis
  16. Fermi GRB 260209A: Global MASTER-Net observations report
  17. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  18. LAT GRB 260208B: Global MASTER-Net observations report
  19. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  20. GRB 260206A: Swift-XRT observations
  21. Fermi trigger No 792135758: Global MASTER-Net observations report
  22. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  23. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  24. EP260131a: SVOM/VT optical observation
  25. GRB 260130A: Fermi GBM Detection
  26. GRB 260127B: Fermi GBM Detection
  27. Fermi GRB 260129A: Global MASTER-Net observations report
  28. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  29. Fermi GRB 260127B: Global MASTER-Net observations report
  30. Swift GRB 260127A: Global MASTER-Net observations report
  31. GRB 260114A: SVOM/VT optical upper limits
  32. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  33. EP260116a: COLIBRÍ further observations
  34. SVOM GRB260121.06: Global MASTER-Net observations report
  35. SVOM GRB260119.90: Global MASTER-Net observations report
  36. EP260119a: Global MASTER-Net observations report
  37. SVOM GRB260117.82: Global MASTER-Net observations report
  38. GRB 260117A: SVOM/C-GFT upper limit
  39. GRB 251222A: radio detection with the VLA
  40. Konus-Wind detection of GRB 251230A / EP251230a
  41. GRB 260112A: Fermi GBM Final Real-time Localization
  42. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  43. Swift Trigger 1434591: possible GRB 260109C
  44. Fermi GRB 260107A: Global MASTER-Net observations report
  45. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  46. The EP-WXT trigger 01709251112 is likely a flaring star
  47. GRB 260105B: Fermi GBM Detection
  48. GRB 260105A: SVOM/GRM observation
  49. The EP-WXT trigger 01709251028 is likely a flaring star
  50. GRB 260105A: Fermi GBM Final Real-time Localization
  51. EP260104a: Global MASTER-Net observations report
  52. EP260105a: Global MASTER-Net observations report
  53. Fermi GRB 260104B: Global MASTER-Net observations report
  54. GRB 260101A: COLIBRÍ optical observations
  55. SVOM GRB260103.08: Global MASTER-Net observations report
  56. GRB 260102B: Fermi GBM Final Real-time Localization
  57. GRB 260102A: EP-FXT follow-up observation
  58. GRB 260101A: NOT spectroscopic observations
  59. Fermi GRB 251228A: Global MASTER-Net observations report
  60. GRB 251228A: Fermi GBM Final Real-time Localization
  61. SVOM GRB251227.07: Global MASTER-Net observations report
  62. GRB 251222A / EP251222b: GOTO optical counterpart detection
  63. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  64. GRB 251222A: SVOM/VT optical candidate
  65. SVOM GRB251219.11: Global MASTER-Net observations report
  66. Fermi trigger No 787736968: Global MASTER-Net observations report
  67. Fermi GRB 251216A: Global MASTER-Net observations report
  68. Fermi GRB 251215A: Global MASTER-Net observations report
  69. EP251214a: Global MASTER-Net observations report
  70. Fermi GRB 251214A: Global MASTER-Net observations report
  71. EP251212a: Global MASTER-Net observations report
  72. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  73. Fermi GBM Sub-Threshold Detection of GRB 251205A
  74. Fermi GRB 251208C: Global MASTER-Net observations report
  75. SVOM GRB251208D: Global MASTER-Net observations report
  76. GRB 251205A: COLIBRÍ optical observations
  77. GRB 251205A: Swift detection of a burst with an optical afterglow
  78. GRB 251203C: EP-FXT follow-up observation
  79. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  80. EP251130a: MAO/AZT-22 optical observations
  81. GRB 251201B: Swift detection of a burst with an optical counterpart
  82. EP251130a: SAO RAS optical observations
  83. EP251130a: Global MASTER-Net observations report
  84. GRB 251128A: SVOM/GRM observation of a long burst
  85. GRB 251128A: Fermi GBM Observation
  86. Fermi GRB 251128A: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  88. EP251118a: Optical detection with Kinder observations
  89. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  90. GRB 251119A: SVOM detection of a possible burst
  91. LAT GRB251118.86: Global MASTER-Net observations report
  92. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  93. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  94. GRB 251116C: LCO optical upper limits
  95. Fermi GRB 251115A: Global MASTER-Net observations report
  96. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  97. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  98. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  99. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  100. GRB 251112B: MAXI/GSC detection

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