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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"

43936 results found.

  1. GRB 250403A: Fermi GBM Final Real-time Localization
  2. GRB 250225B: VLT host galaxy redshift z = 0.950
  3. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  4. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  5. GRB 250402A: REM optical/NIR upper limits
  6. GRB 250402A: LCO optical counterpart detection
  7. GRB 250402A: refined SVOM/MXT data analysis
  8. The EP-WXT trigger 01709133862 is a flaring star
  9. EP250402a: Einstein Probe detection of a fast X-ray transient
  10. GRB 250402B: AstroSat CZTI detection of a short burst
  11. GRB 250402A: SVOM/VT optical counterpart
  12. GRB 250402A: SVOM detection of a burst
  13. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  14. GRB 250314A: ALMA detection
  15. GRB 250327B: Swift/UVOT Detection
  16. GRB 250331E: SVOM/GRM observation
  17. GRB 250327B: Kilonova-Catcher Observations
  18. GRB250331D: AbAO optical observations
  19. GRB 250331D: Fermi GBM observation
  20. GRB 250328A: AbAO AS-32 Optical Observations
  21. GRB 250219A: NOT candidate host galaxy detection
  22. GRB 250322B: GRBAlpha detection
  23. GRB 250331D: Swift-XRT observations
  24. GRB 250331C: Swift-XRT refined Analysis
  25. GRB 250331B: Swift-XRT refined Analysis
  26. GRB 250331B: Swift-XRT refined Analysis
  27. GRB 250322B possible detection by the AstroSat Satellite
  28. GRB 250330B: SVOM/GRM observation of a short burst
  29. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  30. Fermi GRB 250331E: Global MASTER-Net observations report
  31. Fermi GRB 250331D: Global MASTER-Net observations report
  32. GRB 250330B: EIRSAT-1 GMOD Detection
  33. GRB 250331E: Fermi GBM Final Real-time Localization
  34. GRB 250327A Swift-BAT refined analysis
  35. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  36. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  37. Fermi trigger No 765078057: Global MASTER-Net observations report
  38. GRB 250329B: CAHA 2.2m telescope optical limit
  39. GRB 250331D: Swift ToO observations
  40. Swift GRB 250331C: Global MASTER-Net observations report
  41. Swift GRB 250331B: Global MASTER-Net observations report
  42. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  43. Konus-Wind detection of GRB 250327B
  44. GRB 250331C: Enhanced Swift-XRT position
  45. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  46. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  47. GRB 250331B: Enhanced Swift-XRT position
  48. GRB 250320C : SVOM detection of a burst through offline search
  49. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  50. GRB 250329B: Swift-XRT confirmation of fading
  51. GRB 250330A: VLT/FORS2 Afterglow Detection
  52. GRB20250327B: 45th Parallel Observatory upper limit
  53. GRB 250328A: Swift/UVOT Detection
  54. GRB 250328A: Swift-XRT refined Analysis
  55. Fermi-LAT gamma-ray observations of IceCube-250330A
  56. SVOM/sb25033102 is a false trigger
  57. GRB 250330A: Fermi GBM Observation
  58. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  59. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  60. GRB 250331D: Fermi GBM Final Real-time Localization
  61. GRB 250331C: Prompt enhanced Swift-XRT position
  62. GRB 250331C: Swift detection of a burst
  63. GRB 250331B: Swift detection of a burst
  64. GRB 250330A: SVOM/VT optical upper limit
  65. GRB 250331A: MAXI/GSC detection
  66. SVOM/sb25033102: SVOM detection of an X-ray transient
  67. GRB 250314A: VLA detection
  68. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  69. Fermi GRB 250330B: Global MASTER-Net observations report
  70. GRB 250330B: Fermi GBM Final Real-time Localization
  71. Fermi GRB 250330A: Global MASTER-Net observations report
  72. GRB 250330A: BOOTES-7 early optical upper limit
  73. GRB 250330A: Swift-XRT afterglow detection
  74. GRB 250328A: 1.6m Mephisto optical observations
  75. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  76. GRB 250330A: Fermi GBM Final Localization
  77. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  78. IceCube Alert 250330.35: Global MASTER-Net observations report
  79. GRB 250330A: Prompt Swift-XRT position
  80. GRB 250329B: Swift-XRT afterglow detection
  81. GRB 250330A: Swift detection of a burst
  82. Swift GRB250330.26: Global MASTER-Net observations report
  83. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  84. GRB 250329B: SVOM/C-GFT optical upper limit
  85. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  86. GRB 250327B: ALMA detection
  87. GRB 250327B: VLA detection
  88. GRB 250329B: SVOM/VT optical upper limit
  89. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  90. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  91. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  92. GRB250329A: REM optical afterglow detection
  93. GRB 250329B: GWAC-F50A optical upper limit
  94. GRB 250329B: SVOM detection of a faint transient
  95. GRB 250329A: Swift-XRT afterglow detection
  96. GRB 250328A: SVOM/VT optical observation
  97. GRB 250329A: Fading optical counterpart detection by LCO.
  98. GRB 250328A: SVOM/C-GFT optical upper limit
  99. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  100. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate

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