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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"

32713 results found.

  1. EP250427a/GRB 250427A: FTW optical and NIR observations of the counterpart
  2. EP250427a: Lesedi optical counterpart detection
  3. EP250427A: COLIBRÍ Continuing Optical Observations
  4. GRB250427A/EP250427a GIT optical afterglow detection:
  5. EP250427a: LT optical counterpart detection
  6. GRB 250427A: Swift-XRT refined Analysis
  7. EP250427a / GRB 250427A: LCO optical counterpart detection
  8. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  9. EP250427A/GRB250427A: Keck/LRIS redshift
  10. EP250427a: REM optical/NIR afterglow detection
  11. GRB 250424A: LCO optical observation
  12. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  13. EP250427A: COLIBRÍ Optical Detection
  14. EP250427a: TRT optical counterpart detection
  15. EP250427a: Global MASTER-Net observations report
  16. EP250427a: Einstein Probe detection of a fast X-ray transient
  17. GRB 250424A: Swift-BAT refined analysis
  18. IceCube-250426A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  19. GRB 250424A: SVOM/GRM observation of a long burst
  20. GRB 250424A: PRIME near-infrared detection
  21. GRB 250424A: WINTER J-band detection
  22. GRB 250424A: EIRSAT-1 GMOD Detection
  23. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 250424A: SVOM/VT optical observation
  26. GRB 250419A: Mondy Optical Observations
  27. GRB 250424A: Swift/UVOT Detection
  28. Konus-Wind detection of GRB 250424A
  29. Fermi-LAT gamma-ray observations of IceCube-250421A
  30. GRB 250424A: Skynet Optical Observations
  31. GRB 250424A: Kilonova-Catcher optical afterglow detection
  32. GRB 250419a: Continued Liverpool Telescope observations
  33. GRB 250419A: Liverpool Telescope optical upper limit
  34. GRB 250407A: GRBAlpha detection
  35. GRB 250404A / EP250404a: GRBAlpha detection
  36. GRB 250330B: GRBAlpha detection
  37. GRB 250419A: SVOM/ECLAIRs refined analysis
  38. GRB 250424A: AstroSat CZTI detection of a bright long burst
  39. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  40. GRB 250424A: BlackGEM optical afterglow detection
  41. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  42. GRB 250424A: likely host galaxy
  43. GRB 250424A: DDOTI Afterglow Detection
  44. GRB 250424A: REM optical/NIR afterglow detection
  45. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  46. EP250421a: Nickel optical upper limit
  47. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  48. EP250421a: Upper limits from Fermi-GBM Observations
  49. SVOM/sb25042207: XRT observations
  50. SVOM/sb25042207: BOOTES-2 early optical upper limit
  51. SVOM/sb25042207: GOTO optical upper limits
  52. GRB 250421A: AstroSat CZTI detection
  53. GRB250419A: VLA radio detection
  54. IceCube-250421A: DDOTI Detection of the LAST Candidate
  55. GRB 250419A: Mephisto Multi-band Optical Detection
  56. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  57. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  58. EP250421a: NOT optical observations
  59. GRB 250419A: Optical Observations via Virtual Telescope Project
  60. EP250421a: REM optical upper limit
  61. EP250421a: Swift/XRT counterpart detection
  62. EP250421A: COLIBRÍ Optical Upper Limit
  63. GRB 250419A: Mondy Continued Optical Observations
  64. Fermi GRB 250421A: Global MASTER-Net observations report
  65. EP250421a: Global MASTER-Net observations report
  66. EP250421a: Mephisto optical counterpart confirmation
  67. GRB 250419A: Liverpool Telescope observations
  68. GRB 250419A: LCO optical observation
  69. GRB 250419A: JinShan optical observations
  70. GRB 250419A: SVOM/VT optical continuous observations
  71. GRB 250419A: SVOM/C-GFT optical observations
  72. GRB 250419A: Swift/UVOT Follow up
  73. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  74. GRB 250419A: LCO optical afterglow multi-band observations
  75. GRB 250419A: Mondy and AbAO Optical Observations
  76. GRB 250419A: Liverpool Telescope observations
  77. GRB 250419A: AKO Optical Afterglow Detection
  78. GRB 250419A: MASTER optical afterglow observation
  79. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  80. GRB 250407A: rest-frame energetics from Konus-Wind observation
  81. GRB 250419A: Swift-XRT localisation
  82. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  83. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  84. GRB 250419A: Swift-XRT refined Analysis
  85. GRB 250419A: GOTO optical counterpart detection
  86. GRB 250419A: KAIT optical afterglow observations
  87. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  88. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  89. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  90. EP250416a: Swift/XRT counterpart fading
  91. EP250416a: refined EP-WXT and EP-FXT analysis
  92. Konus-Wind detection of GRB 250403A
  93. EP20250416a: Swift/XRT counterpart detection
  94. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  95. IceCube-250416A: DDOTI Optical Observations
  96. EP250416a: Gemini South-GMOS optical counterpart
  97. EP250225a: SVOM/VT optical brightening
  98. SVOM/sb25041603 is not a GRB
  99. EP250416a: GSP optical upper limit
  100. EP250416a: Global MASTER-Net observations report

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