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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"

36349 results found.

  1. GRB 250225B: VLT/FORS2 candidate optical afterglow
  2. GRB 250225B: SVOM/GRM observation of a long burst
  3. GRB 250226A: GECAM-B detection
  4. GRB 250221A: EP-FXT detection of the X-ray afterglow
  5. GRB 250214A: SVOM/GRM observation
  6. EP250226a/GRB 250226A: GSP detects optical counterpart
  7. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  8. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  9. EP250226a / GRB 250226A: TRT optical counterpart observation
  10. Swift GRB 250225B: Global MASTER-Net observations report
  11. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  12. Fermi GRB 250226A: Global MASTER-Net observations report
  13. GRB 250226A: Fermi GBM Final Real-time Localization
  14. Fermi GRB 250225A: Global MASTER-Net observations report
  15. GRB 250225B: Swift detection of a burst
  16. GRB 250221A: Swift-BAT refined analysis
  17. GRB 250223C: SVOM/GRM observation of a long burst
  18. GRB 250225A: Fermi GBM Final Real-time Localization
  19. GRB 250207a: ATCA Radio Upper Limits
  20. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  21. GRB 250119B: VZLUSAT-2 detection
  22. GRB 250223C: Fermi GBM Final Real-time Localization
  23. GRB 250202B: VZLUSAT-2 detection
  24. GRB 250219A: EP-FXT afterglow detection
  25. GRB 250222A: SVOM/GRM observation of a burst
  26. GRB 250210A: VZLUSAT-2 detection
  27. GRB 250206A: VZLUSAT-2 detection
  28. GRB 250221A: TNOT detection of the optical counterpart
  29. 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
  30. EP250223a: OASDG optical observations
  31. GRB 250223B: Fermi GBM Final Localization
  32. GRB 250221A: VLA radio detection
  33. Fermi GRB 250223A: Global MASTER-Net observations report
  34. GRB 250223A: Fermi GBM Final Real-time Localization
  35. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  36. GRB 250221A: continued Mondy optical observations, brightening afterglow
  37. GRB 250221A: Optical counterpart detection by LCO.
  38. GRB 250221A: Mondy optical observations
  39. Konus-Wind detection of GRB 250221A
  40. GRB 250221A: Assy optical observations
  41. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  42. GRB 250221A: VLT/X-shooter redshift z = 0.768
  43. GRB 250221A: GRANDMA/TAROT Detection
  44. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  45. GRB 250221A: Swift-XRT refined Analysis
  46. GRB 250221A: NOT optical observations
  47. GRB 250221A: 1.6m Mephisto optical detection
  48. GRB 250221A: AKO Optical Upper Limit
  49. GRB 250221A: Swift/UVOT Detection
  50. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  51. GRB 250221A: REM optical/NIR afterglow detection
  52. GRB 250221A: Enhanced Swift-XRT position
  53. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  54. GRB 250221A: Swift detection of a burst with an optical counterpart
  55. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  56. GRB 250220B: Fermi GBM Final Real-time Localization
  57. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  58. GRB 250220A: Fermi GBM Final Real-time Localization
  59. Konus-Wind detection of GRB 250217C (short)
  60. GRB 250219A: Swift/UVOT Upper Limits
  61. GRB 250219A: OHP/T193 optical upper limit
  62. GRB 250219A: NOT optical observations
  63. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  64. GRB 250219A: 1.6m Mephisto optical upper limits
  65. GRB 250219A: SVOM/VT optical counterpart
  66. GRB 250219A: Swift-XRT observations
  67. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  68. GRB 250219A: Swift ToO observations
  69. GRB 250219A: SVOM detection of a burst
  70. Konus-Wind detection of GRB 250215A / EP250215a
  71. GRB 250217C: Swift-XRT observations
  72. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  73. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  74. GRB 250217C: SVOM/GRM observation
  75. GRB 250217C: Tiled Swift observations
  76. GRB 250217C: Fermi GBM Observation
  77. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  78. IPN triangulation of GRB 250217C (short)
  79. GRB 250213A: Swift-XRT observations
  80. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  81. GRB 250216A: AstroSat CZTI detection
  82. GRB 250217C: AstroSat CZTI detection of a short burst
  83. Fermi GRB 250217C: Global MASTER-Net observations report
  84. GRB 250217C: Fermi GBM Final Real-time Localization
  85. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  86. Fermi GRB 250217A: Global MASTER-Net observations report
  87. GRANDMA/OPD observations of GRB250215A
  88. GRB 250217B: Fermi GBM Final Real-time Localization
  89. GRB 250217A: Fermi GBM Final Real-time Localization
  90. Fermi GRB 250216A: Global MASTER-Net observations report
  91. GRB 250215A / EP250215a: LCO detection of the afterglow
  92. GRB 250216A: Fermi GBM Final Real-time Localization
  93. GRB 250215A: Swift/UVOT Upper Limits
  94. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  95. EP250215a / GRB 250215A : GTC redshift z = 4.61
  96. GRB 250215A: Fermi GBM Observation
  97. EP250215a / GRB 250215A : NOT optical observations
  98. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  99. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  100. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow

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