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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"

37681 results found.

  1. GRB 250219A: NOT candidate host galaxy detection
  2. GRB 250322B: GRBAlpha detection
  3. GRB 250331D: Swift-XRT observations
  4. GRB 250331C: Swift-XRT refined Analysis
  5. GRB 250331B: Swift-XRT refined Analysis
  6. GRB 250331B: Swift-XRT refined Analysis
  7. GRB 250322B possible detection by the AstroSat Satellite
  8. GRB 250330B: SVOM/GRM observation of a short burst
  9. Fermi GRB 250331E: Global MASTER-Net observations report
  10. Fermi GRB 250331D: Global MASTER-Net observations report
  11. GRB 250330B: EIRSAT-1 GMOD Detection
  12. GRB 250331E: Fermi GBM Final Real-time Localization
  13. GRB 250327A Swift-BAT refined analysis
  14. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  15. Fermi trigger No 765078057: Global MASTER-Net observations report
  16. GRB 250329B: CAHA 2.2m telescope optical limit
  17. GRB 250331D: Swift ToO observations
  18. Swift GRB 250331C: Global MASTER-Net observations report
  19. Swift GRB 250331B: Global MASTER-Net observations report
  20. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  21. Konus-Wind detection of GRB 250327B
  22. GRB 250331C: Enhanced Swift-XRT position
  23. GRB 250331B: Enhanced Swift-XRT position
  24. GRB 250320C : SVOM detection of a burst through offline search
  25. GRB 250329B: Swift-XRT confirmation of fading
  26. GRB 250330A: VLT/FORS2 Afterglow Detection
  27. GRB20250327B: 45th Parallel Observatory upper limit
  28. GRB 250328A: Swift/UVOT Detection
  29. GRB 250328A: Swift-XRT refined Analysis
  30. Fermi-LAT gamma-ray observations of IceCube-250330A
  31. GRB 250330A: Fermi GBM Observation
  32. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  33. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  34. GRB 250331D: Fermi GBM Final Real-time Localization
  35. GRB 250331C: Prompt enhanced Swift-XRT position
  36. GRB 250331C: Swift detection of a burst
  37. GRB 250331B: Swift detection of a burst
  38. GRB 250330A: SVOM/VT optical upper limit
  39. GRB 250331A: MAXI/GSC detection
  40. GRB 250314A: VLA detection
  41. Fermi GRB 250330B: Global MASTER-Net observations report
  42. GRB 250330B: Fermi GBM Final Real-time Localization
  43. Fermi GRB 250330A: Global MASTER-Net observations report
  44. GRB 250330A: BOOTES-7 early optical upper limit
  45. GRB 250330A: Swift/UVOT Upper Limits
  46. GRB 250330A: Swift-XRT afterglow detection
  47. GRB 250328A: 1.6m Mephisto optical observations
  48. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  49. GRB 250330A: Fermi GBM Final Localization
  50. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 250330A: VLT/FORS2 Optical Observations
  52. GRB 250330A: Prompt Swift-XRT position
  53. GRB 250329B: Swift-XRT afterglow detection
  54. GRB 250330A: Swift detection of a burst
  55. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  56. GRB 250329B: SVOM/C-GFT optical upper limit
  57. GRB 250327B: ALMA detection
  58. GRB 250327B: VLA detection
  59. GRB 250329B: SVOM/VT optical upper limit
  60. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  61. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  62. GRB 250329B: GWAC-F50A optical upper limit
  63. GRB 250329B: SVOM detection of a faint transient
  64. GRB 250329A: Swift-XRT afterglow detection
  65. GRB 250328A: SVOM/VT optical observation
  66. GRB 250329A: Fading optical counterpart detection by LCO.
  67. GRB 250328A: SVOM/C-GFT optical upper limit
  68. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  69. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  70. GRB 250329A: VLT/X-shooter redshift z = 2.921
  71. GRB 250329A: SVOM/VT optical counterpart confirmation
  72. GRB 250329A: SVOM detection of a burst
  73. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  74. GRB 250327B: J-band observations with WINTER
  75. GRB 250327B: MASTER detection of OT rebrightening
  76. GRB 250327B: LCO optical counterpart detection
  77. GRB 250328A: GWAC-F50A optical upper limit
  78. GRB 250328A: SVOM detection of a burst
  79. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  80. GRB 250327B: CrAO and SAO RAS Optical Observations
  81. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  82. GRB 250327B: further optical observations by LCOGT
  83. GRB 250327b: Liverpool Telescope optical observations
  84. GRB 250322A: GRANDMA/TNOT optical upper limits
  85. GRB 250327A: SVOM/VT upper limits on the XRT position
  86. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  87. GRB 250327B: Las Cumbres optical counterpart detection
  88. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  89. GRB 250327B: 1.6m Mephisto optical observations
  90. GRB 250327B: NOT spectroscopic redshift z = 3.035
  91. GRB 250327A: Swift-XRT refined Analysis
  92. GRB 250327B: GOTO optical counterpart detection
  93. GRB 250327B: SVOM/VT optically bright counterpart
  94. GRB 250327B: SAO RAS optical candidate
  95. GRB 250327B: SVOM detection of a burst
  96. GRB 250327A: J-band observations with WINTER
  97. GRB 250327A: SVOM/VT optical candidate
  98. GRB 250327A: Fermi GBM observation
  99. Fermi GRB 250327A: Global MASTER-Net observations report
  100. Swift GRB 250327A: Global MASTER-Net observations report

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