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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"

45984 results found.

  1. GRB 250327B: Kilonova-Catcher Observations
  2. GRB250331D: AbAO optical observations
  3. GRB 250331D: Fermi GBM observation
  4. GRB 250331C: Swift/UVOT Upper Limits
  5. GRB 250331B: Swift/UVOT Upper Limits
  6. GRB 250328A: AbAO AS-32 Optical Observations
  7. GRB 250219A: NOT candidate host galaxy detection
  8. GRB 250322B: GRBAlpha detection
  9. GRB 250331D: Swift-XRT observations
  10. GRB 250331C: Swift-XRT refined Analysis
  11. GRB 250331B: Swift-XRT refined Analysis
  12. GRB 250331B: Swift-XRT refined Analysis
  13. GRB 250322B possible detection by the AstroSat Satellite
  14. GRB 250330B: SVOM/GRM observation of a short burst
  15. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  16. Fermi GRB 250331E: Global MASTER-Net observations report
  17. Fermi GRB 250331D: Global MASTER-Net observations report
  18. GRB 250330B: EIRSAT-1 GMOD Detection
  19. GRB 250331E: Fermi GBM Final Real-time Localization
  20. GRB 250327A Swift-BAT refined analysis
  21. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  22. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  23. Fermi trigger No 765078057: Global MASTER-Net observations report
  24. GRB 250329B: CAHA 2.2m telescope optical limit
  25. GRB 250331D: Swift ToO observations
  26. Swift GRB 250331C: Global MASTER-Net observations report
  27. Swift GRB 250331B: Global MASTER-Net observations report
  28. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  29. Konus-Wind detection of GRB 250327B
  30. GRB 250331C: Enhanced Swift-XRT position
  31. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  32. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  33. GRB 250331B: Enhanced Swift-XRT position
  34. GRB 250320C : SVOM detection of a burst through offline search
  35. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  36. GRB 250329B: Swift-XRT confirmation of fading
  37. GRB 250330A: VLT/FORS2 Afterglow Detection
  38. GRB20250327B: 45th Parallel Observatory upper limit
  39. GRB 250328A: Swift/UVOT Detection
  40. GRB 250328A: Swift-XRT refined Analysis
  41. Fermi-LAT gamma-ray observations of IceCube-250330A
  42. SVOM/sb25033102 is a false trigger
  43. GRB 250330A: Fermi GBM Observation
  44. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  45. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  46. GRB 250331D: Fermi GBM Final Real-time Localization
  47. GRB 250331C: Prompt enhanced Swift-XRT position
  48. GRB 250331C: Swift detection of a burst
  49. GRB 250331B: Swift detection of a burst
  50. GRB 250330A: SVOM/VT optical upper limit
  51. GRB 250331A: MAXI/GSC detection
  52. SVOM/sb25033102: SVOM detection of an X-ray transient
  53. GRB 250314A: VLA detection
  54. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  55. Fermi GRB 250330B: Global MASTER-Net observations report
  56. GRB 250330B: Fermi GBM Final Real-time Localization
  57. Fermi GRB 250330A: Global MASTER-Net observations report
  58. GRB 250330A: BOOTES-7 early optical upper limit
  59. GRB 250330A: Swift/UVOT Upper Limits
  60. GRB 250330A: Swift-XRT afterglow detection
  61. GRB 250328A: 1.6m Mephisto optical observations
  62. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  63. GRB 250330A: Fermi GBM Final Localization
  64. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  65. IceCube Alert 250330.35: Global MASTER-Net observations report
  66. GRB 250330A: VLT/FORS2 Optical Observations
  67. GRB 250330A: Prompt Swift-XRT position
  68. GRB 250329B: Swift-XRT afterglow detection
  69. GRB 250330A: Swift detection of a burst
  70. Swift GRB250330.26: Global MASTER-Net observations report
  71. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  72. GRB 250329B: SVOM/C-GFT optical upper limit
  73. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  74. GRB 250327B: ALMA detection
  75. GRB 250327B: VLA detection
  76. GRB 250329B: SVOM/VT optical upper limit
  77. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  78. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  79. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  80. GRB250329A: REM optical afterglow detection
  81. GRB 250329B: GWAC-F50A optical upper limit
  82. GRB 250329B: SVOM detection of a faint transient
  83. GRB 250329A: Swift-XRT afterglow detection
  84. GRB 250328A: SVOM/VT optical observation
  85. GRB 250329A: Fading optical counterpart detection by LCO.
  86. GRB 250328A: SVOM/C-GFT optical upper limit
  87. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  88. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  89. GRB 250329A: VLT/X-shooter redshift z = 2.921
  90. GRB 250329A: SVOM/VT optical counterpart confirmation
  91. GRB 250329A: SVOM detection of a burst
  92. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  93. GRB 250327B: J-band observations with WINTER
  94. GRB 250327B: MASTER detection of OT rebrightening
  95. GRB 250327B: LCO optical counterpart detection
  96. GRB 250328A: GWAC-F50A optical upper limit
  97. GRB 250328A: SVOM detection of a burst
  98. FRB 20250316A: FTW optical observations
  99. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  100. EP250302a: SPI-ACS/INTEGRAL Upper Limit

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