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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"

27222 results found.

  1. GRB 250223A: Fermi GBM Final Real-time Localization
  2. EP250223a: Einstein Probe detection of an X-ray transient
  3. GRB 250221A: Optical counterpart detection by LCO.
  4. EP250220a: FTW optical and NIR observations and upper limits
  5. EP250220a: EP-FXT follow-up observations
  6. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  7. GRB 250221A: GRANDMA/TAROT Detection
  8. Fermi trigger No 761805304: Global MASTER-Net observations report
  9. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  10. GRB 250221A: Swift-XRT refined Analysis
  11. GRB 250221A: NOT optical observations
  12. GRB 250221A: 1.6m Mephisto optical detection
  13. LIGO/Virgo/KAGRA S250221gb: Retraction of GW compact binary merger candidate
  14. GRB 250221A: AKO Optical Upper Limit
  15. GRB 250221A: Swift/UVOT Detection
  16. EP250220a: Liverpool Telescope upper limits
  17. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  18. GRB 250221A: REM optical/NIR afterglow detection
  19. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  20. LIGO/Virgo/KAGRA S250221eb: Retraction of GW compact binary merger candidate
  21. EP250220a: 1.6m Mephisto observations
  22. EP250220a: Optical upper limit with Kinder observations
  23. SVOM trigger sb25022102 is not an astrophysical event
  24. SVOM/sb25022102: SVOM detection of an X-ray transient
  25. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  26. GRB 250221A: Swift detection of a burst with an optical counterpart
  27. Swift GRB250221.15: Global MASTER-Net OT detection
  28. Swift GRB250221.15: Global MASTER-Net observations report
  29. EP250220a: Xinglong optical upper limit
  30. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  31. GRB 250220B: Fermi GBM Final Real-time Localization
  32. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  33. GRB 250220A: Fermi GBM Final Real-time Localization
  34. EP250220a: Global MASTER-Net observations report
  35. EP250220a: EP-WXT detection of a fast X-ray transient
  36. GRB 250219A: Swift/UVOT Upper Limits
  37. GRB 250219A: OHP/T193 optical upper limit
  38. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  39. GRB 250219A: 1.6m Mephisto optical upper limits
  40. GRB 250219A: SVOM/VT optical counterpart
  41. GRB 250219A: SVOM detection of a burst
  42. Konus-Wind detection of GRB 250215A / EP250215a
  43. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  44. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  45. GRB 250217C: SVOM/GRM observation
  46. GRB 250217C: Fermi GBM Observation
  47. IPN triangulation of GRB 250217C (short)
  48. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  49. SVOM/sb25021804: SVOM detection of a long X-ray transient
  50. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  51. Fermi GRB 250217C: Global MASTER-Net observations report
  52. GRB 250217C: Fermi GBM Final Real-time Localization
  53. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  54. Fermi GRB 250217A: Global MASTER-Net observations report
  55. GRB 250217B: Fermi GBM Final Real-time Localization
  56. The EP-WXT trigger 01709131775 is likely a flaring star
  57. GRB 250217A: Fermi GBM Final Real-time Localization
  58. Fermi GRB 250216A: Global MASTER-Net observations report
  59. GRB 250215A / EP250215a: LCO detection of the afterglow
  60. GRB 250216A: Fermi GBM Final Real-time Localization
  61. EP250212a: FTW optical and NIR upper limits
  62. GRB 250215A: Swift/UVOT Upper Limits
  63. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  64. GRB 250215A: Fermi GBM Observation
  65. EP250215a / GRB 250215A : NOT optical observations
  66. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  67. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  68. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  69. GRB 250215A: Swift-XRT refined Analysis
  70. GRB 250215A: SVOM/GRM observation
  71. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  72. EP250215a: Global MASTER-Net observations report
  73. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  74. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  75. Fermi GRB 250215A: Global MASTER-Net observations report
  76. GRB 250215A: Fermi GBM Final Real-time Localization
  77. Fermi trigger No 761206993: Global MASTER-Net observations report
  78. GRB 250213A：SVOM/VT optical candidate
  79. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  80. EP250207b: Xinglong optical upper limit
  81. Fermi GRB 250214A: Global MASTER-Net observations report
  82. GRB 250214A: Fermi GBM Final Real-time Localization
  83. EP250212a: Xinglong optical upper limit
  84. GRB 250213A: SVOM detection of a burst
  85. EP250212a: Global MASTER-Net observations report
  86. GRB 250205A: Leavitt Observatory optical upper limit
  87. EP250207B: Chandra localization of the X-ray counterpart
  88. EP250207b: VLA radio upper limits
  89. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  90. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  91. EP250207B: GTC z-band Observations
  92. Fermi GRB 250212A: Global MASTER-Net observations report
  93. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  94. Fermi trigger No 760945500: Global MASTER-Net observations report
  95. EP250207b: NOT optical counterpart candidate
  96. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  97. Integral GRB250211.89: Global MASTER-Net observations report
  98. GRB 250212A: Fermi GBM Final Real-time Localization
  99. GRB 250207A: Fermi GBM Observation
  100. GRB 250206A: Fermi GBM Observation

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