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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"

3999 results found.

  1. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  2. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  3. GRB 250207B: MAXI/GSC detection
  4. GRB 250202B: Fermi GBM Detection
  5. The EP-WXT trigger 01709131196 is likely a flaring star
  6. Swift GRB250129A: MASTER 4 days observations report
  7. GRB 250129A: optical photometry from Konkoly
  8. GRB 250128B: VLA possible radio detection
  9. GRB 250129A: AKO Optical Afterglow Detection
  10. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  11. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  12. GRB 250128B: VLA radio upper limit
  13. GRB 250129A: Skynet optical observations
  14. GRB 250128B: Gemini-North optical extended source detection
  15. GRB 250128B: TNG optical upper limit
  16. GRB 250129A: REM optical/NIR afterglow detection
  17. GRB 250129A: Early afterglow detection by LCO.
  18. GRB 250129A: LCO optical observations
  19. GRB 250129A: GOTO optical observations show brightening afterglow
  20. Swift GRB 250129A: Global MASTER-Net observations report
  21. The EP-WXT trigger 01709131085 is likely a flaring star
  22. Fermi GRB 250128B: Global MASTER-Net observations report
  23. Swift GRB 250129A: Global MASTER-Net OT detection
  24. GRB 250127A: EP-FXT afterglow detection
  25. Fermi GRB 250127B: Global MASTER-Net observations report
  26. GRB 250126A: MAXI/GSC detection
  27. GECAM-A detection of a bright burst from SGR 1E1841-045
  28. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  29. IPN triangulation of a bright burst from SGR 1E1841-045
  30. IPN triangulation of GRB 250119B
  31. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  32. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  33. GRB 250116A: GECAM-B detection of a long burst
  34. GRB 250114B: OHP/T193 optical upper limit
  35. EP250111a: Global MASTER-Net observations report
  36. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  37. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  38. IPN triangulation of GRB 250107D (short/hard)
  39. EP250109a: SVOM/VT optical candidate
  40. GRB 250106A: SVOM detection of a long burst
  41. Fermi trigger No 757753930: Global MASTER-Net observations report
  42. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  43. Swift GRB 250103B: Global MASTER-Net observations report
  44. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  45. Fermi GRB 250101B: Global MASTER-Net observations report
  46. GRB 250101A: SAO RAS optical observations
  47. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  48. GRB 241228B: SAO RAS optical observations
  49. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  50. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 241229A: EP-FXT afterglow candidates
  52. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  53. GRB 241229C: Fermi GBM Final Real-time Localization
  54. GRB 241229B: Fermi GBM Observation
  55. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  56. Swift GRB 241229B: Global MASTER-Net observations report
  57. GRB 241229A: GOTO optical upper limits
  58. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  59. GRB 241229B: Fermi GBM Final Real-time Localization
  60. GRB 241223A: GRBAlpha detection
  61. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  62. GRB 241029A: AbAO AS-32 optical observations
  63. Fermi trigger No 756678579: Global MASTER-Net observations report
  64. IceCube Alert 241224.30: Global MASTER-Net observations report
  65. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  66. Fermi trigger No 756447119: Global MASTER-Net observations report
  67. Fermi GRB 241221A: Global MASTER-Net observations report
  68. EP241217a: Liverpool Telescope optical upper limit
  69. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  70. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  71. EP241119a: 7DT Optical upper limits
  72. GRB 241213A: REM optical/NIR upper limits
  73. GRB 241207A: TSHAO Zeiss-1000 optical observations
  74. GRB 241129A: Fermi GBM Observation
  75. GRB 241209A: Swift-XRT refined Analysis
  76. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  77. EP241208a: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  79. Fermi GRB 241209E: Global MASTER-Net observations report
  80. Fermi GRB 241209A: Global MASTER-Net observations report
  81. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  82. Fermi GRB 241207A: Global MASTER-Net observations report
  83. GRB 241204A: DDOTI Upper Limits on the Afterglow
  84. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  85. EP241202b: Global MASTER-Net observations report
  86. GRB 241128A: AbAO optical upper limit
  87. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  88. GRB 241128A: Swift-BAT refined analysis
  89. GRB 241128A: Mondy optical observations
  90. Swift GRB 241128A: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  92. GRB 241129A: Fermi GBM Final Real-time Localization
  93. SVOM/GRM observation of GRB 241126B or a short burst from magnetar
  94. EP241126a: TRT optical counterpart detection
  95. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  96. SVOM/GRM detection of a short burst from SGR 1830
  97. GECAM detection of a short burst from SGR 1830
  98. Konus-Wind detection of GRB 241115D / EP 241115a
  99. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  100. Fermi GRB 241118A: Global MASTER-Net observations report

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