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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"

37281 results found.

  1. GRB 250202B: VZLUSAT-2 detection
  2. GRB 250219A: EP-FXT afterglow detection
  3. EP250223a: GOTO optical afterglow detections
  4. GRB 250222A: SVOM/GRM observation of a burst
  5. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  6. GRB 250210A: VZLUSAT-2 detection
  7. GRB 250206A: VZLUSAT-2 detection
  8. EP250223a: 1.6m Mephisto and 50cm array observations
  9. GRB 250221A: TNOT detection of the optical counterpart
  10. 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
  11. EP250223a: OASDG optical observations
  12. EP250223a: LCO detection of the afterglow
  13. EP250223a: NOT optical afterglow candidate
  14. GRB 250223B: Fermi GBM Final Localization
  15. GRB 250221A: VLA radio detection
  16. Fermi GRB 250223A: Global MASTER-Net observations report
  17. GRB 250223A: Fermi GBM Final Real-time Localization
  18. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  19. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  20. GRB 250221A: continued Mondy optical observations, brightening afterglow
  21. GRB 250221A: Optical counterpart detection by LCO.
  22. GRB 250221A: Mondy optical observations
  23. Konus-Wind detection of GRB 250221A
  24. GRB 250221A: Assy optical observations
  25. EP250220a: EP-FXT follow-up observations
  26. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  27. GRB 250221A: VLT/X-shooter redshift z = 0.768
  28. GRB 250221A: GRANDMA/TAROT Detection
  29. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  30. GRB 250221A: Swift-XRT refined Analysis
  31. GRB 250221A: NOT optical observations
  32. GRB 250221A: 1.6m Mephisto optical detection
  33. GRB 250221A: AKO Optical Upper Limit
  34. GRB 250221A: Swift/UVOT Detection
  35. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  36. GRB 250221A: REM optical/NIR afterglow detection
  37. GRB 250221A: Enhanced Swift-XRT position
  38. EP250220a: 1.6m Mephisto observations
  39. EP250220a: Optical upper limit with Kinder observations
  40. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  41. GRB 250221A: Swift detection of a burst with an optical counterpart
  42. Swift GRB250221.15: Global MASTER-Net OT detection
  43. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  44. GRB 250220B: Fermi GBM Final Real-time Localization
  45. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  46. GRB 250220A: Fermi GBM Final Real-time Localization
  47. Konus-Wind detection of GRB 250217C (short)
  48. GRB 250219A: Swift/UVOT Upper Limits
  49. GRB 250219A: OHP/T193 optical upper limit
  50. GRB 250219A: NOT optical observations
  51. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  52. GRB 250219A: 1.6m Mephisto optical upper limits
  53. GRB 250219A: SVOM/VT optical counterpart
  54. GRB 250219A: Swift-XRT observations
  55. GRB 250219A: Swift ToO observations
  56. GRB 250219A: SVOM detection of a burst
  57. Konus-Wind detection of GRB 250215A / EP250215a
  58. GRB 250217C: Swift-XRT observations
  59. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  60. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  61. GRB 250217C: SVOM/GRM observation
  62. GRB 250217C: Tiled Swift observations
  63. GRB 250217C: Fermi GBM Observation
  64. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  65. IPN triangulation of GRB 250217C (short)
  66. GRB 250213A: Swift-XRT observations
  67. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  68. GRB 250216A: AstroSat CZTI detection
  69. GRB 250217C: AstroSat CZTI detection of a short burst
  70. Fermi GRB 250217C: Global MASTER-Net observations report
  71. GRB 250217C: Fermi GBM Final Real-time Localization
  72. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  73. Fermi GRB 250217A: Global MASTER-Net observations report
  74. GRANDMA/OPD observations of GRB250215A
  75. GRB 250217B: Fermi GBM Final Real-time Localization
  76. GRB 250217A: Fermi GBM Final Real-time Localization
  77. Fermi GRB 250216A: Global MASTER-Net observations report
  78. GRB 250215A / EP250215a: LCO detection of the afterglow
  79. GRB 250216A: Fermi GBM Final Real-time Localization
  80. GRB 250215A: Swift/UVOT Upper Limits
  81. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  82. EP250215a / GRB 250215A : GTC redshift z = 4.61
  83. GRB 250215A: Fermi GBM Observation
  84. EP250215a / GRB 250215A : NOT optical observations
  85. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  86. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  87. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  88. GRB 250215A: Swift-XRT refined Analysis
  89. GRB 250215A: SVOM/GRM observation
  90. EP250215a / GRB 250215A: AstroSat CZTI detection
  91. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  92. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  93. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  94. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  95. Fermi GRB 250215A: Global MASTER-Net observations report
  96. GRB 250215A: Fermi GBM Final Real-time Localization
  97. GRB 250213A：SVOM/VT optical candidate
  98. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  99. Fermi GRB 250214A: Global MASTER-Net observations report
  100. GRB 250213A: Swift ToO observations

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