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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"

26718 results found.

  1. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  2. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  3. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 250430A: AKO Optical Afterglow Detection
  5. GRB 250430A: Kanata optical upper limit
  6. EP 250427A: Optical counterpart detection by LCO.
  7. GRB 250430A: Swift detection of a burst with optical counterpart
  8. EP250427a/GRB250427A: HCT optical follow-up
  9. SVOM/sb25043004: SVOM detection of a X-ray transient
  10. EP250428b: refined analysis of the EP-FXT follow-up observation
  11. EP250428b: GROWTH-India telescope optical upper limit
  12. EP250428b: SAO RAS optical upper limit
  13. EP250428b: LAST optical upper limit
  14. GRB 250427A: Swift/UVOT Detection
  15. EP250428b: Einstein Probe detection of a fast X-ray transient
  16. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  17. EP250427a: EP-FXT follow-up observations
  18. EP250427a: Lesedi optical counterpart detection
  19. EP250427A: COLIBRÍ Continuing Optical Observations
  20. GRB250427A/EP250427a GIT optical afterglow detection:
  21. EP250427a: LT optical counterpart detection
  22. GRB 250427A: Swift-XRT refined Analysis
  23. EP250427a / GRB 250427A: LCO optical counterpart detection
  24. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  25. EP250427a: REM optical/NIR afterglow detection
  26. GRB 250424A: LCO optical observation
  27. EP250427A: COLIBRÍ Optical Detection
  28. EP250427a: TRT optical counterpart detection
  29. EP250427a: Einstein Probe detection of a fast X-ray transient
  30. IceCube Alert 250426.74: Global MASTER-Net observations report
  31. GRB 250424A: SVOM/GRM observation of a long burst
  32. GRB 250424A: PRIME near-infrared detection
  33. GRB 250424A: WINTER J-band detection
  34. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  35. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 250419A: Mondy Optical Observations
  37. GRB 250424A: Swift/UVOT Detection
  38. Konus-Wind detection of GRB 250424A
  39. Fermi-LAT gamma-ray observations of IceCube-250421A
  40. GRB 250424A: Skynet Optical Observations
  41. GRB 250424A: Kilonova-Catcher optical afterglow detection
  42. GRB 250419a: Continued Liverpool Telescope observations
  43. GRB 250419A: SVOM/ECLAIRs refined analysis
  44. GRB 250424A: Swift-XRT refined Analysis
  45. GRB 250424A: Enhanced Swift-XRT position
  46. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  47. GRB 250424A: BlackGEM optical afterglow detection
  48. GRB 250424A: DDOTI Afterglow Detection
  49. GRB 250424A: REM optical/NIR afterglow detection
  50. GRB 250424A: Swift detection of a burst with an optical counterpart
  51. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  52. EP250421a: Nickel optical upper limit
  53. SVOM/sb25042207: XRT observations
  54. SVOM/sb25042207: BOOTES-2 early optical upper limit
  55. SVOM/sb25042207: SVOM detection of an X-ray transient
  56. IceCube-250421A: DDOTI Detection of the LAST Candidate
  57. GRB 250419A: Mephisto Multi-band Optical Detection
  58. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  59. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  60. EP250421a: NOT optical observations
  61. GRB 250419A: Optical Observations via Virtual Telescope Project
  62. EP250421a: REM optical upper limit
  63. EP250421a: Swift/XRT counterpart detection
  64. EP250421A: COLIBRÍ Optical Upper Limit
  65. GRB 250419A: Mondy Continued Optical Observations
  66. EP250421a: Einstein Probe detection of an X-ray transient
  67. EP250421a: Mephisto optical counterpart confirmation
  68. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  69. EP250421a: JinShan likely optical counterpart
  70. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  71. GRB 250419A: LCO optical observation
  72. GRB 250419A: JinShan optical observations
  73. GRB 250419A: SVOM/C-GFT optical observations
  74. GRB 250419A: Swift/UVOT Follow up
  75. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  76. GRB 250419A: LCO optical afterglow multi-band observations
  77. GRB 250419A: Mondy and AbAO Optical Observations
  78. GRB 250419A: AKO Optical Afterglow Detection
  79. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  80. GRB 250419A: Swift-XRT refined Analysis
  81. GRB 250419A: KAIT optical afterglow observations
  82. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  83. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  84. GRB 250419A: SVOM detection of a soft burst
  85. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  86. EP250416a: Swift/XRT counterpart fading
  87. EP250416a: refined EP-WXT and EP-FXT analysis
  88. Konus-Wind detection of GRB 250403A
  89. EP20250416a: Swift/XRT counterpart detection
  90. IceCube-250416A: DDOTI Optical Observations
  91. EP250416a: Gemini South-GMOS optical counterpart
  92. SVOM/sb25041603 is not a GRB
  93. EP250416a: Einstein Probe detection of an X-ray transient
  94. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  95. SVOM/sb25041603: SVOM detection of an X-ray transient
  96. IceCube 250414.324: DDOTI Optical Observations
  97. EP250404a: Nanshan 0.43m Telescope optical observatios
  98. GRB 250411A: DDOTI Optical Observations
  99. GRB 250314A: e-MERLIN observations
  100. GRB 250407A: Mondy and AbAO Optical Observations

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