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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 230509B: Tiled Swift observations
  2. GRB 250308A: SVOM/GRM observation of a bright short burst
  3. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  5. GRB 250309A: Fermi GBM Final Real-time Localization
  6. GRB 250306A: EIRSAT-1 GMOD detection
  7. Fermi GRB 250307A: Global MASTER-Net observations report
  8. Konus-Wind detection of GRB 250306A
  9. GRB 250307A: Fermi GBM Final Real-time Localization
  10. GRB 250306A: Swift-BAT refined analysis
  11. GRB 250306A: NuSTAR detection of the prompt emission
  12. GRB 250305A: AstroSat CZTI detection
  13. GRB 250306A: AstroSat CZTI detection
  14. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  15. Swift GRB 250306A: Global MASTER-Net observations report
  16. GRB 250306A: Swift detection of a burst
  17. GRB 250305A: SVOM/GRM observation of a burst
  18. EP250304A: Upper limits from Fermi-GBM Observations
  19. Fermi GRB 250305A: Global MASTER-Net observations report
  20. GRB 250305A: Fermi GBM Final Real-time Localization
  21. EP250302a: Optical Observations at CrAO and SAO RAS
  22. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  23. EP 250304A: Optical counterpart detection by LCO
  24. Konus-Wind detection of GRB 250222A
  25. IPN triangulation of GRB 250222A
  26. EP250302a: Mondy Continued Optical Observations
  27. EP250304a: VLT/X-shooter redshift z = 0.200
  28. EP250302a: Mondy Observations and Optical Light Curve
  29. EP250302a: OHP/T193 optical and spectroscopic observations
  30. GRB 250226A: GRANDMA Optical Observations
  31. EP250302a: Montarrenti Observatory optical detection
  32. Fermi GRB 250302A: Global MASTER-Net observations report
  33. GRB 250302A: Fermi GBM Final Real-time Localization
  34. GRB 250228A: Fermi GBM Final Localization
  35. GRB 250225B: VLT near-infrared afterglow confirmation
  36. Konus-Wind detection of GRB 250226A
  37. GRB 250225B: EIRSAT-1 GMOD Detection
  38. GRB 250226A: KAO Optical Upper Limit
  39. GRB 250226A: AbAO AS-32 Optical Upper Limit
  40. EP250223A: Upper limits from Fermi-GBM Observations
  41. GRB 250225B: VLT/HAWKI near-infrared observations
  42. GRB 250226A: Fermi GBM Observation
  43. GRB 250226A / EP250226a: LCO detection of the afterglow
  44. GRB 250225B: VLT/Xshooter imaging
  45. GRB 250205A / EP250205A: further radio observations with the VLA
  46. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  47. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  48. GRB 250225B: INTEGRAL SPI-ACS detection
  49. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  50. EP250226a / GRB 250226A: SVOM/VT optical observations
  51. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  52. EP250226a/GRB 250226A: 1.6m Mephisto observations
  53. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  54. EP250226a/GRB 250226A: Kinder optical follow-up observations
  55. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  56. Fermi GRB 250226B: Global MASTER-Net observations report
  57. GRB 250226B: Fermi GBM Final Real-time Localization
  58. GRB 250225B: Fermi GBM Observation
  59. GRB 250221A: ATCA Detections and Upper Limits
  60. GRB 250225B: REM NIR upper limits
  61. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  62. Konus-Wind detection of GRB 250225B
  63. EP250223a: CrAO ZTSH optical observation
  64. GRB 250225B: VLT optical and near-infrared candidate counterpart
  65. GRB 250225B: VLT/FORS2 candidate optical afterglow
  66. GRB 250225B: SVOM/GRM observation of a long burst
  67. GRB 250226A: GECAM-B detection
  68. GRB 250221A: EP-FXT detection of the X-ray afterglow
  69. GRB 250214A: SVOM/GRM observation
  70. EP250226a/GRB 250226A: GSP detects optical counterpart
  71. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  72. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  73. EP250226a / GRB 250226A: TRT optical counterpart observation
  74. Swift GRB 250225B: Global MASTER-Net observations report
  75. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  76. Fermi GRB 250226A: Global MASTER-Net observations report
  77. GRB 250226A: Fermi GBM Final Real-time Localization
  78. Fermi GRB 250225A: Global MASTER-Net observations report
  79. GRB 250225B: Swift detection of a burst
  80. GRB 250221A: Swift-BAT refined analysis
  81. GRB 250223C: SVOM/GRM observation of a long burst
  82. GRB 250225A: Fermi GBM Final Real-time Localization
  83. GRB 250207a: ATCA Radio Upper Limits
  84. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  85. GRB 250119B: VZLUSAT-2 detection
  86. GRB 250223C: Fermi GBM Final Real-time Localization
  87. GRB 250202B: VZLUSAT-2 detection
  88. GRB 250219A: EP-FXT afterglow detection
  89. GRB 250222A: SVOM/GRM observation of a burst
  90. GRB 250210A: VZLUSAT-2 detection
  91. GRB 250206A: VZLUSAT-2 detection
  92. GRB 250221A: TNOT detection of the optical counterpart
  93. 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
  94. EP250223a: OASDG optical observations
  95. GRB 250223B: Fermi GBM Final Localization
  96. GRB 250221A: VLA radio detection
  97. Fermi GRB 250223A: Global MASTER-Net observations report
  98. GRB 250223A: Fermi GBM Final Real-time Localization
  99. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  100. GRB 250221A: continued Mondy optical observations, brightening afterglow

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