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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"

36225 results found.

  1. Konus-Wind detection of GRB 250404A / EP250404a
  2. GRB 250404A / EP250404a: Mondy optical observations
  3. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  4. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  5. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  6. GRB 250404A / EP250404a: NOT optical observations
  7. GRB 250331D: Swift-XRT afterglow detection
  8. GRB 250404B: AstroSat CZTI detection of a short burst
  9. GRB 250403A: AstroSat CZTI detection
  10. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  11. EP250404a: REM optical/NIR observations
  12. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  13. EP250404a: LCO optical counterpart detection
  14. Fermi GRB 250404A: Global MASTER-Net observations report
  15. GRB 250403A: Montarrenti Observatory optical detection
  16. GRB 250404A: Fermi GBM Detection
  17. GRB 250403A: KAIT optical observations
  18. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  19. EP250404a: Xinglong-2.16m spectroscopic redshift
  20. GRB 250403A: Fermi GBM observations
  21. GRB 250327B: VIRT Optical Upper Limit
  22. GRB 250331C Swift-BAT refined analysis
  23. GRB 250331B Swift-BAT refined analysis
  24. GRB 250330A Swift-BAT refined analysis
  25. EP250404a: Nanshan/HMT optical counterpart detection
  26. EP250404a: Einstein Probe detection of an X-ray transient
  27. GRB 250404A: Fermi GBM Final Real-time Localization
  28. GRB 250402A: Mondy optical observations
  29. GRB 250403A: Swift/UVOT Detection
  30. GRB 250402A: Swift/UVOT Upper Limits
  31. GRB 250403A: SVOM/VT optical observation
  32. GRB 250403A: REM NIR afterglow detection
  33. GRB 250403A: LCO optical counterpart detection
  34. GRB 250403A: JinShan optical observations
  35. GRB 250402A: EP-FXT afterglow detection
  36. GRB 250403A: Optical counterpart detection by LCO.
  37. GRB 250403A: Swift-XRT observations
  38. GRB 250322A: 10 GHz VLA radio upper limits
  39. Fermi GRB 250403A: Global MASTER-Net observations report
  40. GRB 250403A: GOTO optical counterpart follow-up observations
  41. GRB 250402A: NUTTelA-TAO Early Optical Limits
  42. GRB 250403A: GMG Optical Observation
  43. GRB 250403A: 1.6m Mephisto multi-band optical detection
  44. GRB 250402A: Fermi GBM Observation
  45. GRB 250403A: SVOM/C-GFT optical observations
  46. GRB 250403A: GOTO detection of the optical afterglow
  47. GRB 250402A: Swift-XRT observations
  48. GRB 250403A : SVOM detection of a burst
  49. GRB 250403A: Fermi GBM Final Real-time Localization
  50. GRB 250225B: VLT host galaxy redshift z = 0.950
  51. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  52. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  53. GRB 250402A: REM optical/NIR upper limits
  54. GRB 250402A: LCO optical counterpart detection
  55. GRB 250402A: refined SVOM/MXT data analysis
  56. GRB 250402B: AstroSat CZTI detection of a short burst
  57. GRB 250402A: SVOM/VT optical counterpart
  58. GRB 250402A: SVOM detection of a burst
  59. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  60. GRB 250314A: ALMA detection
  61. GRB 250329B: Swift/UVOT Upper Limit
  62. GRB 250329A: Swift/UVOT Upper Limit
  63. GRB 250327B: Swift/UVOT Detection
  64. GRB 250327A: Swift/UVOT Upper Limits
  65. GRB 250331E: SVOM/GRM observation
  66. GRB 250327B: Kilonova-Catcher Observations
  67. GRB250331D: AbAO optical observations
  68. GRB 250331D: Fermi GBM observation
  69. GRB 250331C: Swift/UVOT Upper Limits
  70. GRB 250331B: Swift/UVOT Upper Limits
  71. GRB 250328A: AbAO AS-32 Optical Observations
  72. GRB 250219A: NOT candidate host galaxy detection
  73. GRB 250322B: GRBAlpha detection
  74. GRB 250331D: Swift-XRT observations
  75. GRB 250331C: Swift-XRT refined Analysis
  76. GRB 250331B: Swift-XRT refined Analysis
  77. GRB 250331B: Swift-XRT refined Analysis
  78. GRB 250322B possible detection by the AstroSat Satellite
  79. GRB 250330B: SVOM/GRM observation of a short burst
  80. Fermi GRB 250331E: Global MASTER-Net observations report
  81. Fermi GRB 250331D: Global MASTER-Net observations report
  82. GRB 250330B: EIRSAT-1 GMOD Detection
  83. GRB 250331E: Fermi GBM Final Real-time Localization
  84. GRB 250327A Swift-BAT refined analysis
  85. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  86. GRB 250329B: CAHA 2.2m telescope optical limit
  87. GRB 250331D: Swift ToO observations
  88. Swift GRB 250331C: Global MASTER-Net observations report
  89. Swift GRB 250331B: Global MASTER-Net observations report
  90. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  91. Konus-Wind detection of GRB 250327B
  92. GRB 250331C: Enhanced Swift-XRT position
  93. GRB 250331B: Enhanced Swift-XRT position
  94. GRB 250320C : SVOM detection of a burst through offline search
  95. GRB 250329B: Swift-XRT confirmation of fading
  96. GRB 250330A: VLT/FORS2 Afterglow Detection
  97. GRB20250327B: 45th Parallel Observatory upper limit
  98. GRB 250328A: Swift/UVOT Detection
  99. GRB 250328A: Swift-XRT refined Analysis
  100. GRB 250330A: Fermi GBM Observation

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