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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"

32590 results found.

  1. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 250424A: SVOM/VT optical observation
  3. GRB 250419A: Mondy Optical Observations
  4. GRB 250424A: Swift/UVOT Detection
  5. Konus-Wind detection of GRB 250424A
  6. Fermi-LAT gamma-ray observations of IceCube-250421A
  7. GRB 250424A: Skynet Optical Observations
  8. GRB 250424A: Kilonova-Catcher optical afterglow detection
  9. GRB 250419a: Continued Liverpool Telescope observations
  10. GRB 250419A: Liverpool Telescope optical upper limit
  11. GRB 250407A: GRBAlpha detection
  12. GRB 250404A / EP250404a: GRBAlpha detection
  13. GRB 250330B: GRBAlpha detection
  14. GRB 250419A: SVOM/ECLAIRs refined analysis
  15. GRB 250424A: AstroSat CZTI detection of a bright long burst
  16. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  17. GRB 250424A: BlackGEM optical afterglow detection
  18. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  19. GRB 250424A: likely host galaxy
  20. GRB 250424A: DDOTI Afterglow Detection
  21. GRB 250424A: REM optical/NIR afterglow detection
  22. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  23. EP250421a: Nickel optical upper limit
  24. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  25. EP250421a: Upper limits from Fermi-GBM Observations
  26. SVOM/sb25042207: XRT observations
  27. SVOM/sb25042207: BOOTES-2 early optical upper limit
  28. SVOM/sb25042207: GOTO optical upper limits
  29. GRB 250421A: AstroSat CZTI detection
  30. GRB250419A: VLA radio detection
  31. IceCube-250421A: DDOTI Detection of the LAST Candidate
  32. GRB 250419A: Mephisto Multi-band Optical Detection
  33. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  34. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  35. EP250421a: NOT optical observations
  36. GRB 250419A: Optical Observations via Virtual Telescope Project
  37. EP250421a: REM optical upper limit
  38. EP250421a: Swift/XRT counterpart detection
  39. EP250421A: COLIBRÍ Optical Upper Limit
  40. GRB 250419A: Mondy Continued Optical Observations
  41. Fermi GRB 250421A: Global MASTER-Net observations report
  42. EP250421a: Global MASTER-Net observations report
  43. EP250421a: Mephisto optical counterpart confirmation
  44. GRB 250419A: Liverpool Telescope observations
  45. GRB 250419A: LCO optical observation
  46. GRB 250419A: JinShan optical observations
  47. GRB 250419A: SVOM/VT optical continuous observations
  48. GRB 250419A: SVOM/C-GFT optical observations
  49. GRB 250419A: Swift/UVOT Follow up
  50. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  51. GRB 250419A: LCO optical afterglow multi-band observations
  52. GRB 250419A: Mondy and AbAO Optical Observations
  53. GRB 250419A: Liverpool Telescope observations
  54. GRB 250419A: AKO Optical Afterglow Detection
  55. GRB 250419A: MASTER optical afterglow observation
  56. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  57. GRB 250407A: rest-frame energetics from Konus-Wind observation
  58. GRB 250419A: Swift-XRT localisation
  59. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  60. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  61. GRB 250419A: Swift-XRT refined Analysis
  62. GRB 250419A: GOTO optical counterpart detection
  63. GRB 250419A: KAIT optical afterglow observations
  64. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  65. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  66. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  67. EP250416a: Swift/XRT counterpart fading
  68. EP250416a: refined EP-WXT and EP-FXT analysis
  69. Konus-Wind detection of GRB 250403A
  70. EP20250416a: Swift/XRT counterpart detection
  71. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  72. IceCube-250416A: DDOTI Optical Observations
  73. EP250416a: Gemini South-GMOS optical counterpart
  74. EP250225a: SVOM/VT optical brightening
  75. SVOM/sb25041603 is not a GRB
  76. EP250416a: GSP optical upper limit
  77. EP250416a: Global MASTER-Net observations report
  78. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  79. GRB 250413A: AstroSat CZTI detection
  80. EP250304a: ATCA radio observations
  81. EP250404a: Nanshan 0.43m Telescope optical observatios
  82. GRB 250411A: DDOTI Optical Observations
  83. Fermi GRB 250411A: Global MASTER-Net observations report
  84. GRB 250407A: Continued KAIT/Nickel optical observations
  85. GRB 250314A: e-MERLIN observations
  86. GRB 250407A: Mondy and AbAO Optical Observations
  87. EP250227a: Further NOT optical observations
  88. GRB 250320B: cubesat Avion detection
  89. IceCube-250406A: Swift-XRT observations
  90. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  91. IPN triangulation of GRB 250407A
  92. EP250407a: Global MASTER-Net observations report
  93. GRB 250407A: LCO detection of a fading optical counterpart
  94. Fermi-LAT gamma-ray observations of IceCube-250406A
  95. EP250407a: Swift-XRT observations
  96. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  97. Konus-Wind detection of GRB 250407A
  98. GRB 250407A: SVOM/GRM observation of a bright long burst
  99. GRB 250407A: EP-WXT afterglow detection
  100. EP250407a: EP-WXT detection of a fast X-ray transient

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