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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"

11519 results found.

  1. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  2. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  3. Konus-Wind detection of GRB 250404A / EP250404a
  4. GRB 250404A / EP250404a: Mondy optical observations
  5. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  6. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  7. GRB 250404A / EP250404a: NOT optical observations
  8. GRB 250403A: AstroSat CZTI detection
  9. EP250404a: REM optical/NIR observations
  10. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  11. EP250404a: LCO optical counterpart detection
  12. Fermi GRB 250404A: Global MASTER-Net observations report
  13. GRB 250403A: Montarrenti Observatory optical detection
  14. GRB 250404A: Fermi GBM Detection
  15. GRB 250403A: KAIT optical observations
  16. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  17. EP250404a: Xinglong-2.16m spectroscopic redshift
  18. GRB 250403A: Fermi GBM observations
  19. EP250404a: Mephisto multi-band optical detection
  20. EP250404a: Nanshan/HMT optical counterpart detection
  21. EP250404a: Einstein Probe detection of an X-ray transient
  22. GRB 250404A: Fermi GBM Final Real-time Localization
  23. GRB 250403A: Swift/UVOT Detection
  24. GRB 250403A: SVOM/VT optical observation
  25. GRB 250403A: REM NIR afterglow detection
  26. GRB 250403A: LCO optical counterpart detection
  27. GRB 250403A: JinShan optical observations
  28. GRB 250403A: Optical counterpart detection by LCO.
  29. GRB 250403A: Swift-XRT observations
  30. Fermi GRB 250403A: Global MASTER-Net observations report
  31. GRB 250403A: GOTO optical counterpart follow-up observations
  32. GRB 250403A: GMG Optical Observation
  33. GRB 250403A: 1.6m Mephisto multi-band optical detection
  34. GRB 250402A: Fermi GBM Observation
  35. GRB 250403A: SVOM/C-GFT optical observations
  36. GRB 250403A: GOTO detection of the optical afterglow
  37. GRB 250403A : SVOM detection of a burst
  38. GRB 250403A: Fermi GBM Final Real-time Localization
  39. GRB 250331E: SVOM/GRM observation
  40. GRB250331D: AbAO optical observations
  41. GRB 250331D: Fermi GBM observation
  42. GRB 250330B: SVOM/GRM observation of a short burst
  43. Fermi GRB 250331E: Global MASTER-Net observations report
  44. Fermi GRB 250331D: Global MASTER-Net observations report
  45. GRB 250330B: EIRSAT-1 GMOD Detection
  46. GRB 250331E: Fermi GBM Final Real-time Localization
  47. Fermi trigger No 765078057: Global MASTER-Net observations report
  48. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  49. Fermi-LAT gamma-ray observations of IceCube-250330A
  50. GRB 250330A: Fermi GBM Observation
  51. GRB 250331D: Fermi GBM Final Real-time Localization
  52. Fermi GRB 250330B: Global MASTER-Net observations report
  53. GRB 250330B: Fermi GBM Final Real-time Localization
  54. Fermi GRB 250330A: Global MASTER-Net observations report
  55. GRB 250330A: BOOTES-7 early optical upper limit
  56. GRB 250330A: Fermi GBM Final Localization
  57. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  58. GRB 250330A: Swift detection of a burst
  59. GRB 250327B: CrAO and SAO RAS Optical Observations
  60. GRB 250327A: SVOM/VT upper limits on the XRT position
  61. GRB 250327A: J-band observations with WINTER
  62. GRB 250327A: SVOM/VT optical candidate
  63. GRB 250327A: Fermi GBM observation
  64. Fermi GRB 250327A: Global MASTER-Net observations report
  65. GRB 250327A: DDOTI Optical Observations
  66. GRB 250327A: COLIBRÍ optical upper limit
  67. GRB 250327A: Fermi GBM Final Real-time Localization
  68. Fermi trigger No 764700395: Global MASTER-Net observations report
  69. GRB 250225B: GECAM-A detection
  70. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  71. GRB 250321C: Fermi GBM Final Real-time Localization
  72. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  73. GRB 250320B: Fermi GBM Observation
  74. GRB 250320B: Fermi-LAT detection
  75. GRB 250320B: SVOM/GRM observation of a long burst
  76. GRB 250320B: AstroSat CZTI detection
  77. Fermi GRB 250320B: Global MASTER-Net observations report
  78. Fermi GRB 250321A: Global MASTER-Net observations report
  79. GRB 250321A: GOTO optical upper limits
  80. EP250226a/GRB 250226A: KAIT optical observations
  81. GRB 250321A: Fermi GBM Observation
  82. GRB 250321A: Swift detection of a burst
  83. GRB 250321A: Fermi GBM Final Real-time Localization
  84. GRB 250320B: Fermi GBM Final Real-time Localization
  85. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  86. GRB 250320A: Fermi GBM Final Real-time Localization
  87. Fermi GRB 250319B: Global MASTER-Net observations report
  88. GRB 250313A: GRBAlpha detection
  89. GRB 250319B: Fermi GBM Final Localization
  90. GRB 250319A: Fermi GBM Final Localization
  91. GRB 250317D: EIRSAT-1 GMOD Detection
  92. Fermi trigger No 763933627: Global MASTER-Net observations report
  93. GRB 250316A: Swift/UVOT Upper Limits
  94. GRB 250316A: AbAO AS-32 Optical Upper Limit
  95. GRB 250316A: Fermi GBM Observation
  96. Fermi trigger No 763862734: Global MASTER-Net observations report
  97. GRB 250317A: Fermi GBM Final Real-time Localization
  98. Fermi GRB 250316A: Global MASTER-Net observations report
  99. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  100. GRB 250316A: Fermi GBM Final Real-time Localization

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