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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

27919 results found.

  1. GRB 250331E: Fermi GBM Final Real-time Localization
  2. GRB 250327A Swift-BAT refined analysis
  3. GRB 250329B: CAHA 2.2m telescope optical limit
  4. GRB 250331D: Swift ToO observations
  5. Swift GRB 250331C: Global MASTER-Net observations report
  6. Swift GRB 250331B: Global MASTER-Net observations report
  7. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  8. Konus-Wind detection of GRB 250327B
  9. GRB 250331C: Enhanced Swift-XRT position
  10. GRB 250331B: Enhanced Swift-XRT position
  11. GRB 250320C : SVOM detection of a burst through offline search
  12. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  13. GRB 250329B: Swift-XRT confirmation of fading
  14. GRB 250330A: VLT/FORS2 Afterglow Detection
  15. GRB20250327B: 45th Parallel Observatory upper limit
  16. GRB 250328A: Swift/UVOT Detection
  17. GRB 250328A: Swift-XRT refined Analysis
  18. GRB 250330A: Fermi GBM Observation
  19. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  20. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  21. GRB 250331D: Fermi GBM Final Real-time Localization
  22. GRB 250331C: Prompt enhanced Swift-XRT position
  23. GRB 250331C: Swift detection of a burst
  24. GRB 250331B: Swift detection of a burst
  25. GRB 250330A: SVOM/VT optical upper limit
  26. GRB 250331A: MAXI/GSC detection
  27. SVOM/sb25033102: SVOM detection of an X-ray transient
  28. GRB 250314A: VLA detection
  29. GRB 250330B: Fermi GBM Final Real-time Localization
  30. GRB 250330A: BOOTES-7 early optical upper limit
  31. GRB 250330A: Swift/UVOT Upper Limits
  32. GRB 250330A: Swift-XRT afterglow detection
  33. GRB 250328A: 1.6m Mephisto optical observations
  34. GRB 250330A: Fermi GBM Final Localization
  35. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 250330A: Prompt Swift-XRT position
  37. GRB 250329B: Swift-XRT afterglow detection
  38. GRB 250330A: Swift detection of a burst
  39. Swift GRB250330.26: Global MASTER-Net observations report
  40. GRB 250329B: SVOM/C-GFT optical upper limit
  41. GRB 250327B: ALMA detection
  42. GRB 250327B: VLA detection
  43. GRB 250329B: SVOM/VT optical upper limit
  44. GRB250329A: REM optical afterglow detection
  45. GRB 250329B: SVOM detection of a faint transient
  46. GRB 250329A: Swift-XRT afterglow detection
  47. GRB 250329A: Fading optical counterpart detection by LCO.
  48. GRB 250328A: SVOM/C-GFT optical upper limit
  49. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  50. GRB 250329A: VLT/X-shooter redshift z = 2.921
  51. GRB 250329A: SVOM detection of a burst
  52. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  53. GRB 250327B: MASTER detection of OT rebrightening
  54. GRB 250327B: LCO optical counterpart detection
  55. GRB 250328A: SVOM detection of a burst
  56. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  57. EP250315a: Pan-STARRS r and i-band imaging and photometry
  58. GRB 250327b: Liverpool Telescope optical observations
  59. GRB 250322A: GRANDMA/TNOT optical upper limits
  60. GRB 250327A: SVOM/VT upper limits on the XRT position
  61. GRB 250327B: Las Cumbres optical counterpart detection
  62. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  63. GRB 250327B: NOT spectroscopic redshift z = 3.035
  64. GRB 250327A: Swift-XRT refined Analysis
  65. GRB 250327B: GOTO optical counterpart detection
  66. GRB 250327B: SVOM detection of a burst
  67. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  68. GRB 250327A: J-band observations with WINTER
  69. GRB 250327A: SVOM/VT optical candidate
  70. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  71. GRB 250327A: Fermi GBM observation
  72. Swift GRB 250327A: Global MASTER-Net observations report
  73. GRB 250327A: DDOTI Optical Observations
  74. GRB 250327A: COLIBRÍ optical upper limit
  75. GRB 250327A: Swift detection of a burst
  76. GRB 250327A: Fermi GBM Final Real-time Localization
  77. Konus-Wind detection of GRB 250322A (short)
  78. IPN triangulation of GRB 250322B
  79. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  80. GRB 250322A: Swift-BAT refined analysis
  81. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  82. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  83. GRB 250322A: Swift/UVOT Upper Limits
  84. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  85. GRB 250321B: Swift-XRT observations
  86. GRB 250322A: Swift-XRT refined Analysis
  87. EP250321a: TNOT Observation of Optical Counterpart
  88. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  89. SVOM/sb25032302: SVOM detection of a long X-ray transient
  90. GRB 250322A: AstroSat CZTI detection of a short burst
  91. GRB 250322B: AstroSat CZTI detection of a bright long burst
  92. GRB250322A: STEP/T80S optical limits
  93. GRB 250322A: VLT optical observations
  94. GRB 250322A: VLT near-infrared observations
  95. GRB 250322A: NOT optical upper limits
  96. GRB 250322A: Enhanced Swift-XRT position
  97. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  98. GRB 250322A: MASTER optical observation
  99. EP250321a: Liverpool Telescope optical follow-up
  100. GRB 250322A: Swift detection of a short burst

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