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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"

27916 results found.

  1. GRB 250331D: Swift ToO observations
  2. Swift GRB 250331C: Global MASTER-Net observations report
  3. Swift GRB 250331B: Global MASTER-Net observations report
  4. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  5. Konus-Wind detection of GRB 250327B
  6. GRB 250331C: Enhanced Swift-XRT position
  7. GRB 250331B: Enhanced Swift-XRT position
  8. GRB 250320C : SVOM detection of a burst through offline search
  9. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  10. GRB 250329B: Swift-XRT confirmation of fading
  11. GRB 250330A: VLT/FORS2 Afterglow Detection
  12. GRB20250327B: 45th Parallel Observatory upper limit
  13. GRB 250328A: Swift/UVOT Detection
  14. GRB 250328A: Swift-XRT refined Analysis
  15. GRB 250330A: Fermi GBM Observation
  16. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  17. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  18. GRB 250331D: Fermi GBM Final Real-time Localization
  19. GRB 250331C: Prompt enhanced Swift-XRT position
  20. GRB 250331C: Swift detection of a burst
  21. GRB 250331B: Swift detection of a burst
  22. GRB 250330A: SVOM/VT optical upper limit
  23. GRB 250331A: MAXI/GSC detection
  24. SVOM/sb25033102: SVOM detection of an X-ray transient
  25. GRB 250314A: VLA detection
  26. GRB 250330B: Fermi GBM Final Real-time Localization
  27. GRB 250330A: BOOTES-7 early optical upper limit
  28. GRB 250330A: Swift/UVOT Upper Limits
  29. GRB 250330A: Swift-XRT afterglow detection
  30. GRB 250328A: 1.6m Mephisto optical observations
  31. GRB 250330A: Fermi GBM Final Localization
  32. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 250330A: Prompt Swift-XRT position
  34. GRB 250329B: Swift-XRT afterglow detection
  35. GRB 250330A: Swift detection of a burst
  36. Swift GRB250330.26: Global MASTER-Net observations report
  37. GRB 250329B: SVOM/C-GFT optical upper limit
  38. GRB 250327B: ALMA detection
  39. GRB 250327B: VLA detection
  40. GRB 250329B: SVOM/VT optical upper limit
  41. GRB250329A: REM optical afterglow detection
  42. GRB 250329B: SVOM detection of a faint transient
  43. GRB 250329A: Swift-XRT afterglow detection
  44. GRB 250329A: Fading optical counterpart detection by LCO.
  45. GRB 250328A: SVOM/C-GFT optical upper limit
  46. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  47. GRB 250329A: VLT/X-shooter redshift z = 2.921
  48. GRB 250329A: SVOM detection of a burst
  49. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  50. GRB 250327B: MASTER detection of OT rebrightening
  51. GRB 250327B: LCO optical counterpart detection
  52. GRB 250328A: SVOM detection of a burst
  53. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  54. EP250315a: Pan-STARRS r and i-band imaging and photometry
  55. GRB 250327b: Liverpool Telescope optical observations
  56. GRB 250322A: GRANDMA/TNOT optical upper limits
  57. GRB 250327A: SVOM/VT upper limits on the XRT position
  58. GRB 250327B: Las Cumbres optical counterpart detection
  59. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  60. GRB 250327B: NOT spectroscopic redshift z = 3.035
  61. GRB 250327A: Swift-XRT refined Analysis
  62. GRB 250327B: GOTO optical counterpart detection
  63. GRB 250327B: SVOM detection of a burst
  64. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  65. GRB 250327A: J-band observations with WINTER
  66. GRB 250327A: SVOM/VT optical candidate
  67. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  68. GRB 250327A: Fermi GBM observation
  69. Swift GRB 250327A: Global MASTER-Net observations report
  70. GRB 250327A: DDOTI Optical Observations
  71. GRB 250327A: COLIBRÍ optical upper limit
  72. GRB 250327A: Swift detection of a burst
  73. GRB 250327A: Fermi GBM Final Real-time Localization
  74. Konus-Wind detection of GRB 250322A (short)
  75. IPN triangulation of GRB 250322B
  76. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  77. GRB 250322A: Swift-BAT refined analysis
  78. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  79. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  80. GRB 250322A: Swift/UVOT Upper Limits
  81. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  82. GRB 250321B: Swift-XRT observations
  83. GRB 250322A: Swift-XRT refined Analysis
  84. EP250321a: TNOT Observation of Optical Counterpart
  85. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  86. SVOM/sb25032302: SVOM detection of a long X-ray transient
  87. GRB 250322A: AstroSat CZTI detection of a short burst
  88. GRB 250322B: AstroSat CZTI detection of a bright long burst
  89. GRB250322A: STEP/T80S optical limits
  90. GRB 250322A: VLT optical observations
  91. GRB 250322A: VLT near-infrared observations
  92. GRB 250322A: NOT optical upper limits
  93. GRB 250322A: Enhanced Swift-XRT position
  94. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  95. GRB 250322A: MASTER optical observation
  96. EP250321a: Liverpool Telescope optical follow-up
  97. GRB 250322A: Swift detection of a short burst
  98. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  99. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  100. GRB 250225B: GECAM-A detection

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