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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

36194 results found.

  1. GRB 250221A: Optical counterpart detection by LCO.
  2. GRB 250221A: Mondy optical observations
  3. Konus-Wind detection of GRB 250221A
  4. GRB 250221A: Assy optical observations
  5. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  6. GRB 250221A: VLT/X-shooter redshift z = 0.768
  7. GRB 250221A: GRANDMA/TAROT Detection
  8. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  9. GRB 250221A: Swift-XRT refined Analysis
  10. GRB 250221A: NOT optical observations
  11. GRB 250221A: 1.6m Mephisto optical detection
  12. GRB 250221A: AKO Optical Upper Limit
  13. GRB 250221A: Swift/UVOT Detection
  14. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  15. GRB 250221A: REM optical/NIR afterglow detection
  16. GRB 250221A: Enhanced Swift-XRT position
  17. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  18. GRB 250221A: Swift detection of a burst with an optical counterpart
  19. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  20. GRB 250220B: Fermi GBM Final Real-time Localization
  21. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  22. GRB 250220A: Fermi GBM Final Real-time Localization
  23. Konus-Wind detection of GRB 250217C (short)
  24. GRB 250219A: Swift/UVOT Upper Limits
  25. GRB 250219A: OHP/T193 optical upper limit
  26. GRB 250219A: NOT optical observations
  27. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  28. GRB 250219A: 1.6m Mephisto optical upper limits
  29. GRB 250219A: SVOM/VT optical counterpart
  30. GRB 250219A: Swift-XRT observations
  31. GRB 250219A: Swift ToO observations
  32. GRB 250219A: SVOM detection of a burst
  33. Konus-Wind detection of GRB 250215A / EP250215a
  34. GRB 250217C: Swift-XRT observations
  35. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  36. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  37. GRB 250217C: SVOM/GRM observation
  38. GRB 250217C: Tiled Swift observations
  39. GRB 250217C: Fermi GBM Observation
  40. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  41. IPN triangulation of GRB 250217C (short)
  42. GRB 250213A: Swift-XRT observations
  43. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  44. GRB 250216A: AstroSat CZTI detection
  45. GRB 250217C: AstroSat CZTI detection of a short burst
  46. Fermi GRB 250217C: Global MASTER-Net observations report
  47. GRB 250217C: Fermi GBM Final Real-time Localization
  48. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  49. Fermi GRB 250217A: Global MASTER-Net observations report
  50. GRANDMA/OPD observations of GRB250215A
  51. GRB 250217B: Fermi GBM Final Real-time Localization
  52. GRB 250217A: Fermi GBM Final Real-time Localization
  53. Fermi GRB 250216A: Global MASTER-Net observations report
  54. GRB 250215A / EP250215a: LCO detection of the afterglow
  55. GRB 250216A: Fermi GBM Final Real-time Localization
  56. GRB 250215A: Swift/UVOT Upper Limits
  57. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  58. EP250215a / GRB 250215A : GTC redshift z = 4.61
  59. GRB 250215A: Fermi GBM Observation
  60. EP250215a / GRB 250215A : NOT optical observations
  61. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  62. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  63. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  64. GRB 250215A: Swift-XRT refined Analysis
  65. GRB 250215A: SVOM/GRM observation
  66. EP250215a / GRB 250215A: AstroSat CZTI detection
  67. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  68. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  69. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  70. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  71. Fermi GRB 250215A: Global MASTER-Net observations report
  72. GRB 250215A: Fermi GBM Final Real-time Localization
  73. GRB 250213A：SVOM/VT optical candidate
  74. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  75. Fermi GRB 250214A: Global MASTER-Net observations report
  76. GRB 250213A: Swift ToO observations
  77. GRB 250214A: Fermi GBM Final Real-time Localization
  78. GRB 250213A: SVOM detection of a burst
  79. GRB 250205A: VIRT Optical Upper Limit
  80. GRB 250205A: Leavitt Observatory optical upper limit
  81. GRB 250210A: GRBAlpha detection
  82. Fermi GRB 250212A: Global MASTER-Net observations report
  83. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  84. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  85. GRB 250211B: A long GRB detected by INTEGRAL
  86. GRB 250211A: Swift ToO observations
  87. GRB 250212A: Fermi GBM Final Real-time Localization
  88. GRB 250207A: Fermi GBM Observation
  89. GRB 250206A: Fermi GBM Observation
  90. GRB 250205A / EP250205A: radio detection with the VLA
  91. Konus-Wind detection of GRB 250207A
  92. Konus-Wind detection of GRB 250206A
  93. GRB 250210A: SVOM/GRM observation of a long burst
  94. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  95. GRB 250207A: Skynet optical afterglow observations
  96. GRB 241128A: VIRT Optical Upper Limit
  97. EP250207A: Upper limits from Fermi-GBM Observations
  98. GRB 250210A: INTEGRAL SPI-ACS detection
  99. GRB 250210A: AstroSat CZTI detection
  100. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)

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