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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"

3038 results found.

  1. GRB 251222A: radio detection with the VLA
  2. Konus-Wind detection of GRB 251230A / EP251230a
  3. GRB 260112A: Fermi GBM Final Real-time Localization
  4. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  5. Swift Trigger 1434591: possible GRB 260109C
  6. Fermi GRB 260107A: Global MASTER-Net observations report
  7. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  8. The EP-WXT trigger 01709251112 is likely a flaring star
  9. GRB 260105B: Fermi GBM Detection
  10. GRB 260105A: SVOM/GRM observation
  11. The EP-WXT trigger 01709251028 is likely a flaring star
  12. GRB 260105A: Fermi GBM Final Real-time Localization
  13. EP260104a: Global MASTER-Net observations report
  14. EP260105a: Global MASTER-Net observations report
  15. Fermi GRB 260104B: Global MASTER-Net observations report
  16. GRB 260101A: COLIBRÍ optical observations
  17. SVOM GRB260103.08: Global MASTER-Net observations report
  18. GRB 260102B: Fermi GBM Final Real-time Localization
  19. GRB 260102A: EP-FXT follow-up observation
  20. GRB 260101A: NOT spectroscopic observations
  21. Fermi GRB 251228A: Global MASTER-Net observations report
  22. GRB 251228A: Fermi GBM Final Real-time Localization
  23. SVOM GRB251227.07: Global MASTER-Net observations report
  24. GRB 251222A / EP251222b: GOTO optical counterpart detection
  25. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  26. GRB 251222A: SVOM/VT optical candidate
  27. SVOM GRB251219.11: Global MASTER-Net observations report
  28. Fermi trigger No 787736968: Global MASTER-Net observations report
  29. Fermi GRB 251216A: Global MASTER-Net observations report
  30. Fermi GRB 251215A: Global MASTER-Net observations report
  31. EP251214a: Global MASTER-Net observations report
  32. Fermi GRB 251214A: Global MASTER-Net observations report
  33. EP251212a: Global MASTER-Net observations report
  34. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  35. Fermi GBM Sub-Threshold Detection of GRB 251205A
  36. Fermi GRB 251208C: Global MASTER-Net observations report
  37. SVOM GRB251208D: Global MASTER-Net observations report
  38. GRB 251205A: COLIBRÍ optical observations
  39. GRB 251205A: Swift detection of a burst with an optical afterglow
  40. GRB 251203C: EP-FXT follow-up observation
  41. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  42. EP251130a: MAO/AZT-22 optical observations
  43. GRB 251201B: Swift detection of a burst with an optical counterpart
  44. EP251130a: SAO RAS optical observations
  45. EP251130a: Global MASTER-Net observations report
  46. GRB 251128A: SVOM/GRM observation of a long burst
  47. GRB 251128A: Fermi GBM Observation
  48. Fermi GRB 251128A: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  50. EP251118a: Optical detection with Kinder observations
  51. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  52. GRB 251119A: SVOM detection of a possible burst
  53. LAT GRB251118.86: Global MASTER-Net observations report
  54. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  55. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  56. GRB 251116C: LCO optical upper limits
  57. Fermi GRB 251115A: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  59. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  60. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  61. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  62. GRB 251112B: MAXI/GSC detection
  63. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  64. SVOM GRB251111.42: Global MASTER-Net observations report
  65. Fermi trigger No 784279167: Global MASTER-Net observations report
  66. SVOM GRB251106.83: Global MASTER-Net observations report
  67. GRB 251106A: MASTER optical observations
  68. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  69. Fermi GRB 251105A: Global MASTER-Net observations report
  70. GRB 251103B: MITSuME Akeno optical upper limits
  71. Fermi GRB 251103A: Global MASTER-Net observations report
  72. GRB 251103B: Swift detection of a burst
  73. GRB 251103A: BOOTES-2/TELMA optical afterglow
  74. GRB 251103A: NOT optical afterglow candidate
  75. Fermi GRB 251102A: Global MASTER-Net observations report
  76. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  77. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  78. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  79. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  80. EP251027.145: COLIBRÍ optical upper limits
  81. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  82. Fermi GRB 251026B: Global MASTER-Net observations report
  83. GRB 251025B: GROWTH-India Telescope optical observations
  84. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB 251024A: Swift detection of a burst
  87. EP251023b: Global MASTER-Net observations report
  88. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  89. GRB 251013C: ISON-Castelgrande observatory optical observations
  90. Fermi GRB 251023A: Global MASTER-Net observations report
  91. GRB 251016B: Fermi GBM Detection
  92. IceCube-251018A: Global MASTER-Net observations report
  93. Fermi GRB 251016B: Global MASTER-Net observations report
  94. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  95. GRB 251013D: Swift-XRT observations
  96. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  97. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  98. GRB 251013C: SAO RAS optical observations
  99. Fermi GRB 251013A: Global MASTER-Net observations report
  100. GRB 251011B : MASTER optical observations

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