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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"

28110 results found.

  1. EP250321A: J band upper limit by SYSU 80cm telescope
  2. EP250404a: Nanshan/HMT optical counterpart detection
  3. EP250404a: Einstein Probe detection of an X-ray transient
  4. GRB 250403A: Swift/UVOT Detection
  5. GRB 250402A: Swift/UVOT Upper Limits
  6. EP250402a: Optical upper limit with Kinder observations
  7. GRB 250403A: REM NIR afterglow detection
  8. GRB 250403A: LCO optical counterpart detection
  9. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  10. GRB 250403A: JinShan optical observations
  11. GRB 250403A: Optical counterpart detection by LCO.
  12. EP250402a: EP-FXT follow-up observations
  13. GRB 250403A: Swift-XRT observations
  14. GRB 250322A: 10 GHz VLA radio upper limits
  15. GRB 250403A: GMG Optical Observation
  16. GRB 250403A: 1.6m Mephisto multi-band optical detection
  17. GRB 250402A: Fermi GBM Observation
  18. GRB 250403A: SVOM/C-GFT optical observations
  19. GRB 250402A: Swift-XRT observations
  20. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  21. GRB 250402A: REM optical/NIR upper limits
  22. GRB 250402A: LCO optical counterpart detection
  23. EP250402a: Einstein Probe detection of a fast X-ray transient
  24. GRB 250402B: AstroSat CZTI detection of a short burst
  25. GRB 250402A: SVOM/VT optical counterpart
  26. GRB 250402A: SVOM detection of a burst
  27. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  28. GRB 250329B: Swift/UVOT Upper Limit
  29. GRB 250329A: Swift/UVOT Upper Limit
  30. GRB 250327B: Swift/UVOT Detection
  31. GRB 250327A: Swift/UVOT Upper Limits
  32. GRB 250331E: SVOM/GRM observation
  33. GRB 250327B: Kilonova-Catcher Observations
  34. GRB250331D: AbAO optical observations
  35. GRB 250331D: Fermi GBM observation
  36. GRB 250331C: Swift/UVOT Upper Limits
  37. GRB 250331B: Swift/UVOT Upper Limits
  38. GRB 250328A: AbAO AS-32 Optical Observations
  39. GRB 250219A: NOT candidate host galaxy detection
  40. GRB 250331D: Swift-XRT observations
  41. GRB 250331C: Swift-XRT refined Analysis
  42. GRB 250331B: Swift-XRT refined Analysis
  43. GRB 250331B: Swift-XRT refined Analysis
  44. GRB 250322B possible detection by the AstroSat Satellite
  45. GRB 250330B: SVOM/GRM observation of a short burst
  46. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  47. GRB 250330B: EIRSAT-1 GMOD Detection
  48. GRB 250327A Swift-BAT refined analysis
  49. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  50. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  51. Swift GRB 250331C: Global MASTER-Net observations report
  52. Swift GRB 250331B: Global MASTER-Net observations report
  53. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  54. GRB 250331C: Enhanced Swift-XRT position
  55. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  56. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  57. GRB 250331B: Enhanced Swift-XRT position
  58. GRB 250320C : SVOM detection of a burst through offline search
  59. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  60. GRB 250330A: VLT/FORS2 Afterglow Detection
  61. GRB20250327B: 45th Parallel Observatory upper limit
  62. GRB 250328A: Swift/UVOT Detection
  63. GRB 250328A: Swift-XRT refined Analysis
  64. Fermi-LAT gamma-ray observations of IceCube-250330A
  65. SVOM/sb25033102 is a false trigger
  66. GRB 250330A: Fermi GBM Observation
  67. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  68. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  69. GRB 250331C: Swift detection of a burst
  70. GRB 250331B: Swift detection of a burst
  71. GRB 250331A: MAXI/GSC detection
  72. SVOM/sb25033102: SVOM detection of an X-ray transient
  73. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  74. GRB 250330A: Swift/UVOT Upper Limits
  75. GRB 250330A: Swift-XRT afterglow detection
  76. GRB 250328A: 1.6m Mephisto optical observations
  77. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  78. GRB 250330A: VLT/FORS2 Optical Observations
  79. GRB 250329B: Swift-XRT afterglow detection
  80. GRB 250330A: Swift detection of a burst
  81. GRB 250329B: SVOM/C-GFT optical upper limit
  82. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  83. GRB 250329B: SVOM/VT optical upper limit
  84. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  85. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  86. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  87. GRB250329A: REM optical afterglow detection
  88. GRB 250329A: Swift-XRT afterglow detection
  89. GRB 250328A: SVOM/VT optical observation
  90. GRB 250329A: Fading optical counterpart detection by LCO.
  91. GRB 250328A: SVOM/C-GFT optical upper limit
  92. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  93. GRB 250329A: SVOM/VT optical counterpart confirmation
  94. GRB 250329A: SVOM detection of a burst
  95. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  96. GRB 250327B: J-band observations with WINTER
  97. GRB 250327B: LCO optical counterpart detection
  98. GRB 250328A: SVOM detection of a burst
  99. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  100. EP250302a: SPI-ACS/INTEGRAL Upper Limit

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