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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"

35427 results found.

  1. GRB 250219A: EP-FXT afterglow detection
  2. GRB 250222A: SVOM/GRM observation of a burst
  3. GRB 250210A: VZLUSAT-2 detection
  4. GRB 250206A: VZLUSAT-2 detection
  5. GRB 250221A: TNOT detection of the optical counterpart
  6. 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
  7. EP250223a: OASDG optical observations
  8. GRB 250223B: Fermi GBM Final Localization
  9. GRB 250221A: VLA radio detection
  10. Fermi GRB 250223A: Global MASTER-Net observations report
  11. GRB 250223A: Fermi GBM Final Real-time Localization
  12. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  13. GRB 250221A: continued Mondy optical observations, brightening afterglow
  14. GRB 250221A: Optical counterpart detection by LCO.
  15. GRB 250221A: Mondy optical observations
  16. Konus-Wind detection of GRB 250221A
  17. GRB 250221A: Assy optical observations
  18. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  19. GRB 250221A: VLT/X-shooter redshift z = 0.768
  20. GRB 250221A: GRANDMA/TAROT Detection
  21. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  22. GRB 250221A: Swift-XRT refined Analysis
  23. GRB 250221A: NOT optical observations
  24. GRB 250221A: 1.6m Mephisto optical detection
  25. GRB 250221A: AKO Optical Upper Limit
  26. GRB 250221A: Swift/UVOT Detection
  27. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  28. GRB 250221A: REM optical/NIR afterglow detection
  29. GRB 250221A: Enhanced Swift-XRT position
  30. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  31. GRB 250221A: Swift detection of a burst with an optical counterpart
  32. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  33. GRB 250220B: Fermi GBM Final Real-time Localization
  34. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  35. GRB 250220A: Fermi GBM Final Real-time Localization
  36. Konus-Wind detection of GRB 250217C (short)
  37. GRB 250219A: Swift/UVOT Upper Limits
  38. GRB 250219A: OHP/T193 optical upper limit
  39. GRB 250219A: NOT optical observations
  40. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  41. GRB 250219A: 1.6m Mephisto optical upper limits
  42. GRB 250219A: SVOM/VT optical counterpart
  43. GRB 250219A: Swift-XRT observations
  44. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  45. GRB 250219A: Swift ToO observations
  46. GRB 250219A: SVOM detection of a burst
  47. Konus-Wind detection of GRB 250215A / EP250215a
  48. GRB 250217C: Swift-XRT observations
  49. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  50. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  51. GRB 250217C: SVOM/GRM observation
  52. GRB 250217C: Tiled Swift observations
  53. GRB 250217C: Fermi GBM Observation
  54. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  55. IPN triangulation of GRB 250217C (short)
  56. GRB 250213A: Swift-XRT observations
  57. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  58. GRB 250216A: AstroSat CZTI detection
  59. GRB 250217C: AstroSat CZTI detection of a short burst
  60. Fermi GRB 250217C: Global MASTER-Net observations report
  61. GRB 250217C: Fermi GBM Final Real-time Localization
  62. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  63. Fermi GRB 250217A: Global MASTER-Net observations report
  64. GRANDMA/OPD observations of GRB250215A
  65. GRB 250217B: Fermi GBM Final Real-time Localization
  66. GRB 250217A: Fermi GBM Final Real-time Localization
  67. Fermi GRB 250216A: Global MASTER-Net observations report
  68. GRB 250215A / EP250215a: LCO detection of the afterglow
  69. GRB 250216A: Fermi GBM Final Real-time Localization
  70. GRB 250215A: Swift/UVOT Upper Limits
  71. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  72. EP250215a / GRB 250215A : GTC redshift z = 4.61
  73. GRB 250215A: Fermi GBM Observation
  74. EP250215a / GRB 250215A : NOT optical observations
  75. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  76. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  77. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  78. GRB 250215A: Swift-XRT refined Analysis
  79. GRB 250215A: SVOM/GRM observation
  80. EP250215a / GRB 250215A: AstroSat CZTI detection
  81. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  82. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  83. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  84. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  85. Fermi GRB 250215A: Global MASTER-Net observations report
  86. GRB 250215A: Fermi GBM Final Real-time Localization
  87. GRB 250213A：SVOM/VT optical candidate
  88. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  89. Fermi GRB 250214A: Global MASTER-Net observations report
  90. GRB 250213A: Swift ToO observations
  91. GRB 250214A: Fermi GBM Final Real-time Localization
  92. GRB 250213A: SVOM detection of a burst
  93. GRB 250205A: VIRT Optical Upper Limit
  94. GRB 250205A: Leavitt Observatory optical upper limit
  95. GRB 250210A: GRBAlpha detection
  96. Fermi GRB 250212A: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  98. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  99. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  100. GRB 250211B: A long GRB detected by INTEGRAL

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