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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"

35429 results found.

  1. GRB 250119B: VZLUSAT-2 detection
  2. GRB 250223C: Fermi GBM Final Real-time Localization
  3. GRB 250202B: VZLUSAT-2 detection
  4. GRB 250219A: EP-FXT afterglow detection
  5. GRB 250222A: SVOM/GRM observation of a burst
  6. GRB 250210A: VZLUSAT-2 detection
  7. GRB 250206A: VZLUSAT-2 detection
  8. GRB 250221A: TNOT detection of the optical counterpart
  9. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  10. EP250223a: OASDG optical observations
  11. GRB 250223B: Fermi GBM Final Localization
  12. GRB 250221A: VLA radio detection
  13. Fermi GRB 250223A: Global MASTER-Net observations report
  14. GRB 250223A: Fermi GBM Final Real-time Localization
  15. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  16. GRB 250221A: continued Mondy optical observations, brightening afterglow
  17. GRB 250221A: Optical counterpart detection by LCO.
  18. GRB 250221A: Mondy optical observations
  19. Konus-Wind detection of GRB 250221A
  20. GRB 250221A: Assy optical observations
  21. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  22. GRB 250221A: VLT/X-shooter redshift z = 0.768
  23. GRB 250221A: GRANDMA/TAROT Detection
  24. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  25. GRB 250221A: Swift-XRT refined Analysis
  26. GRB 250221A: NOT optical observations
  27. GRB 250221A: 1.6m Mephisto optical detection
  28. GRB 250221A: AKO Optical Upper Limit
  29. GRB 250221A: Swift/UVOT Detection
  30. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  31. GRB 250221A: REM optical/NIR afterglow detection
  32. GRB 250221A: Enhanced Swift-XRT position
  33. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  34. GRB 250221A: Swift detection of a burst with an optical counterpart
  35. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  36. GRB 250220B: Fermi GBM Final Real-time Localization
  37. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  38. GRB 250220A: Fermi GBM Final Real-time Localization
  39. Konus-Wind detection of GRB 250217C (short)
  40. GRB 250219A: Swift/UVOT Upper Limits
  41. GRB 250219A: OHP/T193 optical upper limit
  42. GRB 250219A: NOT optical observations
  43. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  44. GRB 250219A: 1.6m Mephisto optical upper limits
  45. GRB 250219A: SVOM/VT optical counterpart
  46. GRB 250219A: Swift-XRT observations
  47. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  48. GRB 250219A: Swift ToO observations
  49. GRB 250219A: SVOM detection of a burst
  50. Konus-Wind detection of GRB 250215A / EP250215a
  51. GRB 250217C: Swift-XRT observations
  52. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  53. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  54. GRB 250217C: SVOM/GRM observation
  55. GRB 250217C: Tiled Swift observations
  56. GRB 250217C: Fermi GBM Observation
  57. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  58. IPN triangulation of GRB 250217C (short)
  59. GRB 250213A: Swift-XRT observations
  60. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  61. GRB 250216A: AstroSat CZTI detection
  62. GRB 250217C: AstroSat CZTI detection of a short burst
  63. Fermi GRB 250217C: Global MASTER-Net observations report
  64. GRB 250217C: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  66. Fermi GRB 250217A: Global MASTER-Net observations report
  67. GRANDMA/OPD observations of GRB250215A
  68. GRB 250217B: Fermi GBM Final Real-time Localization
  69. GRB 250217A: Fermi GBM Final Real-time Localization
  70. Fermi GRB 250216A: Global MASTER-Net observations report
  71. GRB 250215A / EP250215a: LCO detection of the afterglow
  72. GRB 250216A: Fermi GBM Final Real-time Localization
  73. GRB 250215A: Swift/UVOT Upper Limits
  74. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  75. EP250215a / GRB 250215A : GTC redshift z = 4.61
  76. GRB 250215A: Fermi GBM Observation
  77. EP250215a / GRB 250215A : NOT optical observations
  78. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  79. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  80. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  81. GRB 250215A: Swift-XRT refined Analysis
  82. GRB 250215A: SVOM/GRM observation
  83. EP250215a / GRB 250215A: AstroSat CZTI detection
  84. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  85. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  86. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  87. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  88. Fermi GRB 250215A: Global MASTER-Net observations report
  89. GRB 250215A: Fermi GBM Final Real-time Localization
  90. GRB 250213A：SVOM/VT optical candidate
  91. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  92. Fermi GRB 250214A: Global MASTER-Net observations report
  93. GRB 250213A: Swift ToO observations
  94. GRB 250214A: Fermi GBM Final Real-time Localization
  95. GRB 250213A: SVOM detection of a burst
  96. GRB 250205A: VIRT Optical Upper Limit
  97. GRB 250205A: Leavitt Observatory optical upper limit
  98. GRB 250210A: GRBAlpha detection
  99. Fermi GRB 250212A: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber

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