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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.

Advanced Search Examples (click to copy):

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

3869 results found.

  1. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  2. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  3. GRB 250116A: GECAM-B detection of a long burst
  4. GRB 250114B: OHP/T193 optical upper limit
  5. EP250111a: Global MASTER-Net observations report
  6. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  7. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  8. IPN triangulation of GRB 250107D (short/hard)
  9. EP250109a: SVOM/VT optical candidate
  10. GRB 250106A: SVOM detection of a long burst
  11. Fermi trigger No 757753930: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  13. Swift GRB 250103B: Global MASTER-Net observations report
  14. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  15. Fermi GRB 250101B: Global MASTER-Net observations report
  16. GRB 250101A: SAO RAS optical observations
  17. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  18. GRB 241228B: SAO RAS optical observations
  19. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  20. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  21. GRB 241229A: EP-FXT afterglow candidates
  22. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  23. GRB 241229C: Fermi GBM Final Real-time Localization
  24. GRB 241229B: Fermi GBM Observation
  25. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  26. Swift GRB 241229B: Global MASTER-Net observations report
  27. GRB 241229A: GOTO optical upper limits
  28. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  29. GRB 241229B: Fermi GBM Final Real-time Localization
  30. GRB 241223A: GRBAlpha detection
  31. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  32. GRB 241029A: AbAO AS-32 optical observations
  33. Fermi trigger No 756678579: Global MASTER-Net observations report
  34. IceCube Alert 241224.30: Global MASTER-Net observations report
  35. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  36. Fermi trigger No 756447119: Global MASTER-Net observations report
  37. Fermi GRB 241221A: Global MASTER-Net observations report
  38. EP241217a: Liverpool Telescope optical upper limit
  39. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  40. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  41. EP241119a: 7DT Optical upper limits
  42. GRB 241213A: REM optical/NIR upper limits
  43. GRB 241207A: TSHAO Zeiss-1000 optical observations
  44. GRB 241129A: Fermi GBM Observation
  45. GRB 241209A: Swift-XRT refined Analysis
  46. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  47. EP241208a: Global MASTER-Net observations report
  48. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  49. Fermi GRB 241209E: Global MASTER-Net observations report
  50. Fermi GRB 241209A: Global MASTER-Net observations report
  51. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  52. Fermi GRB 241207A: Global MASTER-Net observations report
  53. GRB 241204A: DDOTI Upper Limits on the Afterglow
  54. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  55. EP241202b: Global MASTER-Net observations report
  56. GRB 241128A: AbAO optical upper limit
  57. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  58. GRB 241128A: Swift-BAT refined analysis
  59. GRB 241128A: Mondy optical observations
  60. Swift GRB 241128A: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  62. GRB 241129A: Fermi GBM Final Real-time Localization
  63. SVOM/GRM observation of GRB 241126B or a short burst from magnetar
  64. EP241126a: TRT optical counterpart detection
  65. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  66. SVOM/GRM detection of a short burst from SGR 1830
  67. GECAM detection of a short burst from SGR 1830
  68. Konus-Wind detection of GRB 241115D / EP 241115a
  69. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  70. Fermi GRB 241118A: Global MASTER-Net observations report
  71. EP241113b: Global MASTER-Net observations report
  72. SVOM/GRM detection of a short burst from SGR 1E1841-045
  73. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  74. Fermi trigger No 752990530: Global MASTER-Net observations report
  75. Fermi trigger No 752878030: Global MASTER-Net observations report
  76. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  77. EP241107a: FTW Optical and NIR observations of the optical counterpart
  78. GRB 241030A: Mondy optical observations
  79. Fermi GRB 241105A: Global MASTER-Net observations report
  80. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  81. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  82. EP241021a: OHP/T193 further optical observations
  83. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  84. EP241103a: Global MASTER-Net observations report
  85. GRB 241029A: GRBAlpha detection
  86. GRB241030A: OHP/T193 optical observations
  87. GRB 241029A: LCO optical detection
  88. Fermi trigger No 752006065: Global MASTER-Net observations report
  89. EP241021a: Swift-UVOT detection
  90. EP241021a: Optical rebrightening observations with Mephisto
  91. GRB 241029A: GROWTH-India Telescope optical follow up
  92. GRB 241029A: SAO RAS optical observations
  93. GRB 241026A: SAO RAS optical observations
  94. EP241021a: SAO RAS observations of rebrightening
  95. GRB 241029A: Fermi GBM Observation
  96. GRB 241029A: AKO Optical Afterglow Detection
  97. GRB 241029A: GOTO optical afterglow detection
  98. GRB 241029A: MASTER early optical counterpart detection
  99. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  100. GRB 241029A: Mephisto observations

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