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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"

28301 results found.

  1. GRB 250403A: Optical counterpart detection by LCO.
  2. EP250402a: EP-FXT follow-up observations
  3. GRB 250403A: Swift-XRT observations
  4. GRB 250322A: 10 GHz VLA radio upper limits
  5. GRB 250403A: GMG Optical Observation
  6. GRB 250403A: 1.6m Mephisto multi-band optical detection
  7. GRB 250402A: Fermi GBM Observation
  8. GRB 250403A: SVOM/C-GFT optical observations
  9. GRB 250402A: Swift-XRT observations
  10. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  11. GRB 250402A: REM optical/NIR upper limits
  12. GRB 250402A: LCO optical counterpart detection
  13. EP250402a: Einstein Probe detection of a fast X-ray transient
  14. GRB 250402B: AstroSat CZTI detection of a short burst
  15. GRB 250402A: SVOM/VT optical counterpart
  16. GRB 250402A: SVOM detection of a burst
  17. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  18. GRB 250329B: Swift/UVOT Upper Limit
  19. GRB 250329A: Swift/UVOT Upper Limit
  20. GRB 250327B: Swift/UVOT Detection
  21. GRB 250327A: Swift/UVOT Upper Limits
  22. GRB 250331E: SVOM/GRM observation
  23. GRB 250327B: Kilonova-Catcher Observations
  24. GRB250331D: AbAO optical observations
  25. GRB 250331D: Fermi GBM observation
  26. GRB 250331C: Swift/UVOT Upper Limits
  27. GRB 250331B: Swift/UVOT Upper Limits
  28. GRB 250328A: AbAO AS-32 Optical Observations
  29. GRB 250219A: NOT candidate host galaxy detection
  30. GRB 250331D: Swift-XRT observations
  31. GRB 250331C: Swift-XRT refined Analysis
  32. GRB 250331B: Swift-XRT refined Analysis
  33. GRB 250331B: Swift-XRT refined Analysis
  34. GRB 250322B possible detection by the AstroSat Satellite
  35. GRB 250330B: SVOM/GRM observation of a short burst
  36. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  37. GRB 250330B: EIRSAT-1 GMOD Detection
  38. GRB 250327A Swift-BAT refined analysis
  39. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  40. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  41. Swift GRB 250331C: Global MASTER-Net observations report
  42. Swift GRB 250331B: Global MASTER-Net observations report
  43. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  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 250330A: VLT/FORS2 Afterglow Detection
  51. GRB20250327B: 45th Parallel Observatory upper limit
  52. GRB 250328A: Swift/UVOT Detection
  53. GRB 250328A: Swift-XRT refined Analysis
  54. Fermi-LAT gamma-ray observations of IceCube-250330A
  55. SVOM/sb25033102 is a false trigger
  56. GRB 250330A: Fermi GBM Observation
  57. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  58. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  59. GRB 250331C: Swift detection of a burst
  60. GRB 250331B: Swift detection of a burst
  61. GRB 250331A: MAXI/GSC detection
  62. SVOM/sb25033102: SVOM detection of an X-ray transient
  63. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  64. GRB 250330A: Swift/UVOT Upper Limits
  65. GRB 250330A: Swift-XRT afterglow detection
  66. GRB 250328A: 1.6m Mephisto optical observations
  67. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  68. GRB 250330A: VLT/FORS2 Optical Observations
  69. GRB 250329B: Swift-XRT afterglow detection
  70. GRB 250330A: Swift detection of a burst
  71. GRB 250329B: SVOM/C-GFT optical upper limit
  72. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  73. GRB 250329B: SVOM/VT optical upper limit
  74. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  75. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  76. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  77. GRB250329A: REM optical afterglow detection
  78. GRB 250329A: Swift-XRT afterglow detection
  79. GRB 250328A: SVOM/VT optical observation
  80. GRB 250329A: Fading optical counterpart detection by LCO.
  81. GRB 250328A: SVOM/C-GFT optical upper limit
  82. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  83. GRB 250329A: SVOM/VT optical counterpart confirmation
  84. GRB 250329A: SVOM detection of a burst
  85. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  86. GRB 250327B: J-band observations with WINTER
  87. GRB 250327B: LCO optical counterpart detection
  88. GRB 250328A: SVOM detection of a burst
  89. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  90. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  91. GRB 250327B: CrAO and SAO RAS Optical Observations
  92. GRB 250327b: Liverpool Telescope optical observations
  93. GRB 250322A: GRANDMA/TNOT optical upper limits
  94. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  95. GRB 250327A: SVOM/VT upper limits on the XRT position
  96. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  97. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  98. GRB 250327B: Las Cumbres optical counterpart detection
  99. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  100. GRB 250327B: 1.6m Mephisto optical observations

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