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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"

3533 results found.

  1. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  2. IPN triangulation of GRB 251129B (short/hard)
  3. GRB 251130B: AstroSat CZTI detection
  4. GRB 251201B: Swift detection of a burst with an optical counterpart
  5. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  6. Fermi GRB 251130B: Global MASTER-Net observations report
  7. EP251130a: COLIBRÍ optical counterpart candidate
  8. GRB 251128A: AstroSat CZTI detection
  9. GRB 251126A: SAO RAS optical observations
  10. GRB 251128A: Fermi GBM Observation
  11. Fermi GRB 251128A: Global MASTER-Net observations report
  12. GRB 251126A: further SAO RAS optical observations
  13. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  14. GRB 251128A: Fermi GBM Final Real-time Localization
  15. Fermi GRB 251125A: Global MASTER-Net observations report
  16. EP251118a: Xinglong-2.16m optical observation
  17. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  18. GRB 251018A: FRAM-Auger optical detection
  19. LAT GRB251118.86: Global MASTER-Net observations report
  20. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  21. GRB 251115A: Swift-XRT observations
  22. GRB 251116C: Swift-XRT observations
  23. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  24. GRB 251116C: SVOM/VT optical upper limit
  25. GRB 251025B: further Mondy optical observations
  26. Fermi GRB 251115A: Global MASTER-Net observations report
  27. GRB 251112A: Swift-BAT refined analysis
  28. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  29. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  30. Fermi GRB 251114A: Global MASTER-Net observations report
  31. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  32. Swift Trigger 1413695: a possible GRB 251112A
  33. GRB 251111A: SVOM/VT optical observations with X-band data
  34. GRB 251105A: AstroSat CZTI detection
  35. SVOM GRB251108.54: Global MASTER-Net observations report
  36. SVOM GRB251106.83: Global MASTER-Net observations report
  37. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  38. GRB 251104A: SVOM detection of a burst
  39. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  40. Fermi GRB 251103A: Global MASTER-Net observations report
  41. Fermi GRB 251102A: Global MASTER-Net observations report
  42. GRB 251028A: Fermi GBM Observation
  43. GRB 251026B: LBT near-infrared observations
  44. GRB 251028B: Fermi/GBM observation
  45. GRB 251028B: Glowbug gamma-ray detection
  46. GRB 251028A: Glowbug gamma-ray detection
  47. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  48. Fermi GRB 251028B: Global MASTER-Net observations report
  49. GRB 251028B: Fermi GBM Final Localization Correction
  50. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  51. GRB 251028A: MAXI/GSC detection
  52. GRB 251028A: Fermi GBM Final Real-time Localization
  53. The EP-WXT trigger 01709247525 is not a real source
  54. EP251023b: Global MASTER-Net observations report
  55. Fermi GRB 251023A: Global MASTER-Net observations report
  56. EP/WXT 01709247295: GOTO optical afterglow candidate.
  57. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  58. EP251021b: Einstein Probe detection of a fast X-ray transient
  59. IceCube-251018A: Global MASTER-Net observations report
  60. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  61. Fermi GRB 251016B: Global MASTER-Net observations report
  62. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  63. sb25101602: Swift-XRT counterpart detection
  64. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  65. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  66. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  67. GRB 251014A: Fermi GBM Observation
  68. GRB 251014A: Swift detection of a possibly-short burst
  69. GRB 251014A: Fermi GBM Final Real-time Localization
  70. Fermi GRB 251013C: Global MASTER-Net observations report
  71. Fermi GRB 251013B: Global MASTER-Net observations report
  72. Fermi GRB 251011A: Global MASTER-Net observations report
  73. GRB 250919A: TERI gamma-ray detection
  74. Fermi GRB 251006B: Global MASTER-Net observations report
  75. GRB 251005C: AstroSat CZTI detection
  76. GRB 251003A: Swift-BAT refined analysis
  77. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  78. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  79. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  80. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  81. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  82. GRB 250924A: J-band detection with WINTER
  83. GRB 250920B: CrAO ZTSH optical observations
  84. Fermi trigger No 780156732: Global MASTER-Net observations report
  85. IPN triangulation of GRB 250920A (long/bright)
  86. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  87. GRB 250919A: Glowbug gamma-ray detection
  88. GRB 250919A: Fermi GBM Observation
  89. GRB 250919A: Fermi-LAT detection
  90. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  91. EP250919a: Global MASTER-Net observations report
  92. GRB 250919A: Fermi GBM Final Real-time Localization
  93. EP250827b: VLA Observations
  94. Fermi GRB 250912A: Global MASTER-Net observations report
  95. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  96. Fermi GRB 250910B: Global MASTER-Net observations report
  97. EP250911a: Einstein Probe detection of an X-ray transient
  98. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  99. Fermi GRB 250909A: Global MASTER-Net observations report
  100. GRB 250909A: Fermi GBM Final Real-time Localization

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