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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23211 results found.

  1. Konus-Wind detection of GRB 250407A
  2. GRB 250407A: SVOM/GRM observation of a bright long burst
  3. GRB 250407A: EP-WXT afterglow detection
  4. EP250407a: EP-WXT detection of a fast X-ray transient
  5. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  6. GRB 250407A: KAIT Optical Afterglow Candidate
  7. IceCube-250406A: No candidates from the Zwicky Transient Facility
  8. GRB 250407A: Fermi GBM Detection
  9. GRB 250407A: Swift-XRT afterglow detection
  10. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  11. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  12. Konus-Wind detection of GRB 250406B (short/hard)
  13. IPN triangulation of GRB 250406B (short/hard)
  14. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  15. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  16. IceCube 250406.951: DDOTI Optical Observations
  17. GRB 250406A: AstroSat CZTI detection
  18. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  19. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  20. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  21. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  22. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  23. Konus-Wind detection of GRB 250404A / EP250404a
  24. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  26. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  27. EP250402a: Optical upper limit with PD 1.3m observations
  28. GRB 250404A / EP250404a: NOT optical observations
  29. GRB 250331D: Swift-XRT afterglow detection
  30. GRB 250403A: AstroSat CZTI detection
  31. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  32. EP250404a: REM optical/NIR observations
  33. EP250404a: Seimei/TriCCS optical counterpart detection
  34. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  35. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  36. EP250404a: LCO optical counterpart detection
  37. EP250404a: Xinglong decaying optical counterpart
  38. GRB 250403A: Montarrenti Observatory optical detection
  39. GRB 250404A: Fermi GBM Detection
  40. GRB 250403A: KAIT optical observations
  41. EP250404a: AKO Optical Afterglow Detection
  42. EP250404a: LAST detection of optical counterpart
  43. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  44. EP250404a: Xinglong-2.16m spectroscopic redshift
  45. GRB 250403A: Fermi GBM observations
  46. GRB 250327B: VIRT Optical Upper Limit
  47. EP250404a: Mephisto multi-band optical detection
  48. EP250321A: J band upper limit by SYSU 80cm telescope
  49. EP250404a: Nanshan/HMT optical counterpart detection
  50. EP250404a: Einstein Probe detection of an X-ray transient
  51. GRB 250403A: Swift/UVOT Detection
  52. GRB 250402A: Swift/UVOT Upper Limits
  53. EP250402a: Optical upper limit with Kinder observations
  54. GRB 250403A: REM NIR afterglow detection
  55. GRB 250403A: LCO optical counterpart detection
  56. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  57. GRB 250403A: JinShan optical observations
  58. GRB 250402A: EP-FXT afterglow detection
  59. GRB 250403A: Optical counterpart detection by LCO.
  60. EP250402a: EP-FXT follow-up observations
  61. GRB 250403A: Swift-XRT observations
  62. GRB 250403A: GMG Optical Observation
  63. GRB 250403A: 1.6m Mephisto multi-band optical detection
  64. GRB 250402A: Fermi GBM Observation
  65. GRB 250403A: SVOM/C-GFT optical observations
  66. GRB 250402A: Swift-XRT observations
  67. GRB 250403A : SVOM detection of a burst
  68. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  69. GRB 250402A: REM optical/NIR upper limits
  70. GRB 250402A: LCO optical counterpart detection
  71. The EP-WXT trigger 01709133862 is a flaring star
  72. EP250402a: Einstein Probe detection of a fast X-ray transient
  73. GRB 250402A: SVOM/VT optical counterpart
  74. GRB 250402A: SVOM detection of a burst
  75. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  76. GRB 250329B: Swift/UVOT Upper Limit
  77. GRB 250329A: Swift/UVOT Upper Limit
  78. GRB 250327B: Swift/UVOT Detection
  79. GRB 250327A: Swift/UVOT Upper Limits
  80. GRB 250331E: SVOM/GRM observation
  81. GRB 250327B: Kilonova-Catcher Observations
  82. GRB250331D: AbAO optical observations
  83. GRB 250331D: Fermi GBM observation
  84. GRB 250331C: Swift/UVOT Upper Limits
  85. GRB 250331B: Swift/UVOT Upper Limits
  86. GRB 250328A: AbAO AS-32 Optical Observations
  87. GRB 250219A: NOT candidate host galaxy detection
  88. GRB 250331D: Swift-XRT observations
  89. GRB 250331C: Swift-XRT refined Analysis
  90. GRB 250331B: Swift-XRT refined Analysis
  91. GRB 250331B: Swift-XRT refined Analysis
  92. GRB 250330B: SVOM/GRM observation of a short burst
  93. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  94. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  95. Konus-Wind detection of GRB 250327B
  96. GRB 250331C: Enhanced Swift-XRT position
  97. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 250331B: Enhanced Swift-XRT position
  99. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  100. GRB 250330A: VLT/FORS2 Afterglow Detection

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