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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"

36191 results found.

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

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