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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"

32770 results found.

  1. Konus-Wind detection of GRB 250404A / EP250404a
  2. GRB 250404A / EP250404a: Mondy optical observations
  3. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  5. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  6. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  7. EP250402a: Optical upper limit with PD 1.3m observations
  8. GRB 250404A / EP250404a: NOT optical observations
  9. GRB 250403A: AstroSat CZTI detection
  10. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  11. EP250404a: REM optical/NIR observations
  12. EP250404a: Seimei/TriCCS optical counterpart detection
  13. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  14. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  15. EP250404a: LCO optical counterpart detection
  16. Fermi GRB 250404A: Global MASTER-Net observations report
  17. GRB 250403A: Montarrenti Observatory optical detection
  18. EP250404a: Global MASTER-Net observations report
  19. GRB 250403A: KAIT optical observations
  20. EP250404a: AKO Optical Afterglow Detection
  21. EP250404a: LAST detection of optical counterpart
  22. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  23. EP250404a: Xinglong-2.16m spectroscopic redshift
  24. GRB 250403A: Fermi GBM observations
  25. GRB 250327B: VIRT Optical Upper Limit
  26. EP250404a: Mephisto multi-band optical detection
  27. GRB 250331C Swift-BAT refined analysis
  28. GRB 250331B Swift-BAT refined analysis
  29. GRB 250330A Swift-BAT refined analysis
  30. EP250321A: J band upper limit by SYSU 80cm telescope
  31. EP250404a: BOOTES-4/JGT optical afterglow detection
  32. EP250404a: Nanshan/HMT optical counterpart detection
  33. EP250404a: Einstein Probe detection of an X-ray transient
  34. GRB 250402A: Mondy optical observations
  35. GRB 250403A: Swift/UVOT Detection
  36. GRB 250402A: Swift/UVOT Upper Limits
  37. EP250402a: Optical upper limit with Kinder observations
  38. GRB 250403A: SVOM/VT optical observation
  39. GRB 250403A: REM NIR afterglow detection
  40. GRB 250403A: LCO optical counterpart detection
  41. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  42. GRB 250403A: JinShan optical observations
  43. GRB 250402A: EP-FXT afterglow detection
  44. GRB 250403A: Optical counterpart detection by LCO.
  45. EP250402a: EP-FXT follow-up observations
  46. GRB 250403A: Swift-XRT observations
  47. GRB 250322A: 10 GHz VLA radio upper limits
  48. Fermi GRB 250403A: Global MASTER-Net observations report
  49. GRB 250403A: GOTO optical counterpart follow-up observations
  50. GRB 250402A: NUTTelA-TAO Early Optical Limits
  51. GRB 250403A: GMG Optical Observation
  52. GRB 250403A: 1.6m Mephisto multi-band optical detection
  53. GRB 250402A: Fermi GBM Observation
  54. GRB 250403A: SVOM/C-GFT optical observations
  55. GRB 250403A: GOTO detection of the optical afterglow
  56. GRB 250402A: Swift-XRT observations
  57. GRB 250403A : SVOM detection of a burst
  58. GRB 250225B: VLT host galaxy redshift z = 0.950
  59. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  60. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  61. GRB 250402A: REM optical/NIR upper limits
  62. GRB 250402A: LCO optical counterpart detection
  63. GRB 250402A: refined SVOM/MXT data analysis
  64. GRB 250402A: SVOM/VT optical counterpart
  65. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  66. GRB 250314A: ALMA detection
  67. GRB 250329B: Swift/UVOT Upper Limit
  68. GRB 250329A: Swift/UVOT Upper Limit
  69. GRB 250327B: Swift/UVOT Detection
  70. GRB 250327A: Swift/UVOT Upper Limits
  71. GRB 250331E: SVOM/GRM observation
  72. GRB 250327B: Kilonova-Catcher Observations
  73. GRB250331D: AbAO optical observations
  74. GRB 250331D: Fermi GBM observation
  75. GRB 250331C: Swift/UVOT Upper Limits
  76. GRB 250331B: Swift/UVOT Upper Limits
  77. GRB 250328A: AbAO AS-32 Optical Observations
  78. GRB 250219A: NOT candidate host galaxy detection
  79. GRB 250322B: GRBAlpha detection
  80. GRB 250330B: SVOM/GRM observation of a short burst
  81. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  82. Fermi GRB 250331E: Global MASTER-Net observations report
  83. Fermi GRB 250331D: Global MASTER-Net observations report
  84. GRB 250330B: EIRSAT-1 GMOD Detection
  85. GRB 250327A Swift-BAT refined analysis
  86. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  87. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  88. GRB 250331D: Swift ToO observations
  89. Swift GRB 250331C: Global MASTER-Net observations report
  90. Swift GRB 250331B: Global MASTER-Net observations report
  91. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  92. Konus-Wind detection of GRB 250327B
  93. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 250329B: Swift-XRT confirmation of fading
  95. GRB 250330A: VLT/FORS2 Afterglow Detection
  96. GRB20250327B: 45th Parallel Observatory upper limit
  97. GRB 250328A: Swift/UVOT Detection
  98. GRB 250328A: Swift-XRT refined Analysis
  99. Fermi-LAT gamma-ray observations of IceCube-250330A
  100. SVOM/sb25033102 is a false trigger

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