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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"

32568 results found.

  1. EP250223a: TRT optical afterglow observation
  2. EP250223a: refined analysis of the EP-WXT and FXT observations
  3. EP250223a: 1.6m Mephisto and 50cm array observations
  4. GRB 250221A: TNOT detection of the optical counterpart
  5. EP250223a: SVOM/VT optical observation
  6. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  7. 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
  8. EP250223a: OASDG optical observations
  9. EP250223a: LCO detection of the afterglow
  10. EP250223a: NOT redshift z = 2.756
  11. EP250223a: Swift/XRT localization
  12. EP250223a: NOT optical afterglow candidate
  13. EP250223a: Global MASTER-Net observations report
  14. GRB 250221A: VLA radio detection
  15. Fermi GRB 250223A: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  17. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  18. GRB 250221A: continued Mondy optical observations, brightening afterglow
  19. GRB 250221A: Optical counterpart detection by LCO.
  20. GRB 250221A: Mondy optical observations
  21. Konus-Wind detection of GRB 250221A
  22. GRB 250221A: Assy optical observations
  23. EP250220a: FTW optical and NIR observations and upper limits
  24. EP250220a: EP-FXT follow-up observations
  25. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  26. GRB 250221A: VLT/X-shooter redshift z = 0.768
  27. GRB 250221A: GRANDMA/TAROT Detection
  28. GRB 250221A: NOT optical observations
  29. GRB 250221A: 1.6m Mephisto optical detection
  30. GRB 250221A: AKO Optical Upper Limit
  31. GRB 250221A: Swift/UVOT Detection
  32. EP250220a: Liverpool Telescope upper limits
  33. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  34. GRB 250221A: REM optical/NIR afterglow detection
  35. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  36. EP250220a: 1.6m Mephisto observations
  37. EP250220a: Liverpool Telescope optical upper limits
  38. EP250220a: Optical upper limit with Kinder observations
  39. SVOM trigger sb25022102 is not an astrophysical event
  40. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  41. EP250220a: Xinglong optical upper limit
  42. EP250220a: Global MASTER-Net observations report
  43. Konus-Wind detection of GRB 250217C (short)
  44. GRB 250219A: Swift/UVOT Upper Limits
  45. GRB 250219A: OHP/T193 optical upper limit
  46. GRB 250219A: NOT optical observations
  47. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  48. GRB 250219A: 1.6m Mephisto optical upper limits
  49. GRB 250219A: SVOM/VT optical counterpart
  50. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  51. GRB 250219A: Swift ToO observations
  52. Konus-Wind detection of GRB 250215A / EP250215a
  53. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  54. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  55. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  56. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  57. GRB 250217C: SVOM/GRM observation
  58. GRB 250217C: Tiled Swift observations
  59. GRB 250217C: Fermi GBM Observation
  60. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  61. IPN triangulation of GRB 250217C (short)
  62. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  63. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  64. GRB 250216A: AstroSat CZTI detection
  65. GRB 250217C: AstroSat CZTI detection of a short burst
  66. Fermi GRB 250217C: Global MASTER-Net observations report
  67. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  68. Fermi GRB 250217A: Global MASTER-Net observations report
  69. GRANDMA/OPD observations of GRB250215A
  70. Fermi GRB 250216A: Global MASTER-Net observations report
  71. GRB 250215A / EP250215a: LCO detection of the afterglow
  72. EP250212a: FTW optical and NIR upper limits
  73. GRB 250215A: Swift/UVOT Upper Limits
  74. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  75. EP250215a / GRB 250215A : GTC redshift z = 4.61
  76. GRB 250215A: Fermi GBM Observation
  77. EP250215a / GRB 250215A : NOT optical observations
  78. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  79. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  80. LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
  81. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  82. GRB 250215A: Swift-XRT refined Analysis
  83. GRB 250215A: SVOM/GRM observation
  84. EP250215a / GRB 250215A: AstroSat CZTI detection
  85. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  86. EP250215a: Global MASTER-Net observations report
  87. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  88. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  89. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  90. Fermi GRB 250215A: Global MASTER-Net observations report
  91. GRB 250213A：SVOM/VT optical candidate
  92. EP250207b: Xinglong optical upper limit
  93. Fermi GRB 250214A: Global MASTER-Net observations report
  94. GRB 250213A: Swift ToO observations
  95. EP250212a: Xinglong optical upper limit
  96. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  97. EP250212a: Global MASTER-Net observations report
  98. GRB 250205A: VIRT Optical Upper Limit
  99. GRB 250205A: Leavitt Observatory optical upper limit
  100. GRB 250210A: GRBAlpha detection

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