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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"

32687 results found.

  1. GRB 250407A: Fermi GBM Detection
  2. GRB 250407A: Swift-XRT afterglow detection
  3. Fermi GRB 250407A: Global MASTER-Net observations report
  4. GRB 250407A: Swift ToO observations
  5. GRB 250407A: SRG/ART-XC afterglow detection
  6. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  7. Konus-Wind detection of GRB 250406B (short/hard)
  8. IPN triangulation of GRB 250406B (short/hard)
  9. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  10. GRB 250406A: AstroSat CZTI detection
  11. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  12. Fermi GRB 250406A: Global MASTER-Net observations report
  13. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  14. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  15. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  16. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  17. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  18. Konus-Wind detection of GRB 250404A / EP250404a
  19. GRB 250404A / EP250404a: Mondy optical observations
  20. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  22. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  23. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  24. EP250402a: Optical upper limit with PD 1.3m observations
  25. GRB 250404A / EP250404a: NOT optical observations
  26. GRB 250403A: AstroSat CZTI detection
  27. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  28. EP250404a: REM optical/NIR observations
  29. EP250404a: Seimei/TriCCS optical counterpart detection
  30. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  31. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  32. EP250404a: LCO optical counterpart detection
  33. Fermi GRB 250404A: Global MASTER-Net observations report
  34. GRB 250403A: Montarrenti Observatory optical detection
  35. EP250404a: Global MASTER-Net observations report
  36. GRB 250403A: KAIT optical observations
  37. EP250404a: AKO Optical Afterglow Detection
  38. EP250404a: LAST detection of optical counterpart
  39. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  40. EP250404a: Xinglong-2.16m spectroscopic redshift
  41. GRB 250403A: Fermi GBM observations
  42. GRB 250327B: VIRT Optical Upper Limit
  43. EP250404a: Mephisto multi-band optical detection
  44. GRB 250331C Swift-BAT refined analysis
  45. GRB 250331B Swift-BAT refined analysis
  46. GRB 250330A Swift-BAT refined analysis
  47. EP250321A: J band upper limit by SYSU 80cm telescope
  48. EP250404a: BOOTES-4/JGT optical afterglow detection
  49. EP250404a: Nanshan/HMT optical counterpart detection
  50. EP250404a: Einstein Probe detection of an X-ray transient
  51. GRB 250402A: Mondy optical observations
  52. GRB 250403A: Swift/UVOT Detection
  53. GRB 250402A: Swift/UVOT Upper Limits
  54. EP250402a: Optical upper limit with Kinder observations
  55. GRB 250403A: SVOM/VT optical observation
  56. GRB 250403A: REM NIR afterglow detection
  57. GRB 250403A: LCO optical counterpart detection
  58. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  59. GRB 250403A: JinShan optical observations
  60. GRB 250402A: EP-FXT afterglow detection
  61. GRB 250403A: Optical counterpart detection by LCO.
  62. EP250402a: EP-FXT follow-up observations
  63. GRB 250403A: Swift-XRT observations
  64. GRB 250322A: 10 GHz VLA radio upper limits
  65. Fermi GRB 250403A: Global MASTER-Net observations report
  66. GRB 250403A: GOTO optical counterpart follow-up observations
  67. GRB 250402A: NUTTelA-TAO Early Optical Limits
  68. GRB 250403A: GMG Optical Observation
  69. GRB 250403A: 1.6m Mephisto multi-band optical detection
  70. GRB 250402A: Fermi GBM Observation
  71. GRB 250403A: SVOM/C-GFT optical observations
  72. GRB 250403A: GOTO detection of the optical afterglow
  73. GRB 250402A: Swift-XRT observations
  74. GRB 250403A : SVOM detection of a burst
  75. GRB 250225B: VLT host galaxy redshift z = 0.950
  76. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  77. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  78. GRB 250402A: REM optical/NIR upper limits
  79. GRB 250402A: LCO optical counterpart detection
  80. GRB 250402A: refined SVOM/MXT data analysis
  81. GRB 250402A: SVOM/VT optical counterpart
  82. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  83. GRB 250314A: ALMA detection
  84. GRB 250329B: Swift/UVOT Upper Limit
  85. GRB 250329A: Swift/UVOT Upper Limit
  86. GRB 250327B: Swift/UVOT Detection
  87. GRB 250327A: Swift/UVOT Upper Limits
  88. GRB 250331E: SVOM/GRM observation
  89. GRB 250327B: Kilonova-Catcher Observations
  90. GRB250331D: AbAO optical observations
  91. GRB 250331D: Fermi GBM observation
  92. GRB 250331C: Swift/UVOT Upper Limits
  93. GRB 250331B: Swift/UVOT Upper Limits
  94. GRB 250328A: AbAO AS-32 Optical Observations
  95. GRB 250219A: NOT candidate host galaxy detection
  96. GRB 250322B: GRBAlpha detection
  97. GRB 250330B: SVOM/GRM observation of a short burst
  98. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  99. Fermi GRB 250331E: Global MASTER-Net observations report
  100. Fermi GRB 250331D: Global MASTER-Net observations report

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