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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"

613 results found.

  1. Fermi GRB 251013A: Global MASTER-Net observations report
  2. GRB 250909A: AstroSat CZTI detection
  3. EP250901a: Mondy, Assy and SAO RAS optical limits
  4. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  5. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  6. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  7. GRB 250831A: Swift-XRT counterpart detection
  8. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  9. GRB 250831A: SVOM/VT upper limit with VHF data
  10. EP250711a: COLIBRÍ continuous optical observations
  11. IceCube-250708A: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  13. EP250610a: Global MASTER-Net observations report
  14. GRB 250516A: Swift-BAT refined analysis
  15. MAXI GRB250515.65: Global MASTER-Net observations report
  16. GRB 250430A: Swift-BAT refined analysis
  17. Fermi GRB 250502B: Global MASTER-Net observations report
  18. Fermi-LAT gamma-ray observations of IceCube-250421A
  19. GRB 250327A: Swift-XRT refined Analysis
  20. GRB 250327A: SVOM/VT optical candidate
  21. GRB 250322A: AstroSat CZTI detection of a short burst
  22. Fermi trigger No 763509110: Global MASTER-Net observations report
  23. Fermi GRB 250309B: Global MASTER-Net observations report
  24. GRB 250226A: Fermi GBM Observation
  25. Fermi GRB 250223A: Global MASTER-Net observations report
  26. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  27. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  29. GRB 250207A: REM IR afterglow detection
  30. GRB 250207A: REM optical afterglow detection
  31. GRB 250114B: OHP/T193 optical upper limit
  32. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  33. GRB 241207C: MASTER optical observations
  34. Fermi trigger No 755225799: Global MASTER-Net observations report
  35. Swift GRB 241128A: Global MASTER-Net observations report
  36. Swift GRB241127.91: Global MASTER-Net observations report
  37. GRB 241113A: Swift/UVOT Detection
  38. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  39. Fermi GRB 240918A: Global MASTER-Net observations report
  40. EP EP240913a: Global MASTER-Net observations report
  41. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  42. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  43. GRB 240829A: Swift-BAT refined analysis
  44. LAT GRB240828.62: Global MASTER-Net observations report
  45. Fermi trigger No 745866488: Global MASTER-Net observations report
  46. Fermi trigger No 745057312: Global MASTER-Net observations report
  47. Swift GRB 240811A: Global MASTER-Net observations report
  48. GRB 240727C: AstroSat CZTI detection of a long burst
  49. Konus-Wind detection of GRB 240627A
  50. Fermi GRB 240702A: Global MASTER-Net observations report
  51. Fermi trigger No 741211696: Global MASTER-Net observations report
  52. Swift Trigger 1232465: consistent with noise
  53. Konus-Wind detection of GRB 240529A
  54. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  55. GRB 240419B: Swift-BAT refined analysis
  56. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  57. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  58. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  59. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  60. Swift GRB 240419B: Global MASTER-Net observations report
  61. GRB 240414A: Swift-BAT refined analysis
  62. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  63. Fermi GRB 240408A: Global MASTER-Net observations report
  64. Konus-Wind detection of LXT 240402A/GRB 240402B
  65. Konus-Wind detection of GRB 240303B
  66. GRB 240222A: Swift/UVOT Upper Limits
  67. GRB 240109A: Swift-BAT refined analysis
  68. GRB 231215A: radio detection with the VLA
  69. GRB 231129A: Swift-BAT refined analysis
  70. GRB 231129A: BOOTES-5/JGT optical upper limit
  71. GRB 231118A: Swift-BAT refined analysis
  72. GRB 231111A: Swift-BAT refined analysis
  73. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  74. IceCube Alert 231027.18: Global MASTER-Net observations report
  75. GRB 230919A: AstroSat CZTI detection
  76. GRB 230911C: Swift-BAT refined analysis
  77. GRB 230826A: Swift-BAT refined analysis
  78. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  79. Fermi GRB 230827A: Global MASTER-Net observations report
  80. Swift GRB230825.75: Global MASTER-Net observations report
  81. Fermi GRB 230814A: Global MASTER-Net observations report
  82. Swift GRB230728.12: Global MASTER-Net observations report
  83. Fermi-LAT gamma-ray observations of IceCube-230725A
  84. IceCube-230725A - IceCube observation of a high-energy neutrino candidate track-like event
  85. LIGO/Virgo S230622e: Global MASTER-Net observations report
  86. LIGO/Virgo S230615be: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  88. GRB 230430A: AstroSat CZTI detection
  89. IPN triangulation of GRB 230418A (short)
  90. Fermi GRB 230402A: Global MASTER-Net observations report
  91. Fermi GRB 230227A: Global MASTER-Net observations report
  92. Fermi GRB 230215A: Global MASTER-Net observations report
  93. GRB 221231A: Fermi GBM Observation
  94. GRB 230101A: AstroSat CZTI detection
  95. Fermi GRB 221223A: Global MASTER-Net observations report
  96. GRB 221216A: Swift-XRT refined Analysis
  97. Fermi trigger No 687190301: Global MASTER-Net observations report
  98. GRB 220831A: ATCA 5/9 GHz radio observations
  99. GRB 220711B: Fermi GBM Detection
  100. GRB 220624A: Fermi GBM Detection

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