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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"

36341 results found.

  1. GRB 250311B: SVOM detection of a burst
  2. GRB 250309B: SVOM/VT optical observation
  3. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  4. GRB 250309B / AT2025dws: further SAO RAS optical observations
  5. IceCube-250309A: Upper limits from Fermi-GBM Observations
  6. Konus-Wind detection of GRB 250309B
  7. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  8. IPN triangulation of GRB 250308A (short)
  9. IPN triangulation of GRB 250309B
  10. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  11. GRB 250309B: Swift-XRT refined Analysis
  12. GRB 250309B / IceCube-250309A: GECAM-B observations
  13. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  14. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  15. GRB 250309B / AT2025dws: SAO RAS optical observations
  16. GRB 250309B / AT2025dws: Swift-UVOT detection
  17. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  18. GRB 250309B: Fermi GBM Observation
  19. Fermi GRB 250309B: Global MASTER-Net observations report
  20. Fermi GRB 250309A: Global MASTER-Net observations report
  21. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  22. Fermi-LAT gamma-ray observations of IceCube-250309A
  23. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  24. GRB 250309B: Fermi GBM Final Localization
  25. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  26. GRB 230509B: Tiled Swift observations
  27. GRB 250308A: SVOM/GRM observation of a bright short burst
  28. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  30. GRB 250309A: Fermi GBM Final Real-time Localization
  31. GRB 250306A: EIRSAT-1 GMOD detection
  32. Fermi GRB 250307A: Global MASTER-Net observations report
  33. Konus-Wind detection of GRB 250306A
  34. GRB 250307A: Fermi GBM Final Real-time Localization
  35. GRB 250306A: Swift-BAT refined analysis
  36. GRB 250306A: NuSTAR detection of the prompt emission
  37. GRB 250305A: AstroSat CZTI detection
  38. GRB 250306A: AstroSat CZTI detection
  39. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  40. Swift GRB 250306A: Global MASTER-Net observations report
  41. GRB 250306A: Swift detection of a burst
  42. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  43. GRB 250305A: SVOM/GRM observation of a burst
  44. EP250304A: Upper limits from Fermi-GBM Observations
  45. Fermi GRB 250305A: Global MASTER-Net observations report
  46. GRB 250305A: Fermi GBM Final Real-time Localization
  47. EP250302a: Optical Observations at CrAO and SAO RAS
  48. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  49. EP 250304A: Optical counterpart detection by LCO
  50. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  51. Konus-Wind detection of GRB 250222A
  52. IPN triangulation of GRB 250222A
  53. EP250302a: Mondy Continued Optical Observations
  54. EP250304a: VLT/X-shooter redshift z = 0.200
  55. EP250302a: NUTTelA-TAO Early Measurments
  56. EP250302a: Mondy Observations and Optical Light Curve
  57. EP250302a: OHP/T193 optical and spectroscopic observations
  58. GRB 250226A: GRANDMA Optical Observations
  59. EP250302a: Montarrenti Observatory optical detection
  60. Fermi GRB 250302A: Global MASTER-Net observations report
  61. GRB 250302A: Fermi GBM Final Real-time Localization
  62. GRB 250228A: Fermi GBM Final Localization
  63. GRB 250225B: VLT near-infrared afterglow confirmation
  64. Konus-Wind detection of GRB 250226A
  65. GRB 250225B: EIRSAT-1 GMOD Detection
  66. GRB 250226A: KAO Optical Upper Limit
  67. GRB 250226A: AbAO AS-32 Optical Upper Limit
  68. EP250223A: Upper limits from Fermi-GBM Observations
  69. GRB 250225B: VLT/HAWKI near-infrared observations
  70. GRB 250226A: Fermi GBM Observation
  71. GRB 250226A / EP250226a: LCO detection of the afterglow
  72. GRB 250225B: VLT/Xshooter imaging
  73. GRB 250205A / EP250205A: further radio observations with the VLA
  74. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  75. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  76. GRB 250225B: INTEGRAL SPI-ACS detection
  77. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  78. EP250226a / GRB 250226A: SVOM/VT optical observations
  79. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  80. EP250226a/GRB 250226A: 1.6m Mephisto observations
  81. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  82. EP250226a/GRB 250226A: Kinder optical follow-up observations
  83. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  84. Fermi GRB 250226B: Global MASTER-Net observations report
  85. GRB 250226B: Fermi GBM Final Real-time Localization
  86. GRB 250225B: Fermi GBM Observation
  87. GRB 250221A: ATCA Detections and Upper Limits
  88. GRB 250225B: REM NIR upper limits
  89. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  90. Konus-Wind detection of GRB 250225B
  91. EP250223a: CrAO ZTSH optical observation
  92. GRB 250225B: VLT optical and near-infrared candidate counterpart
  93. GRB 250225B: VLT/FORS2 candidate optical afterglow
  94. GRB 250225B: SVOM/GRM observation of a long burst
  95. GRB 250226A: GECAM-B detection
  96. GRB 250221A: EP-FXT detection of the X-ray afterglow
  97. GRB 250214A: SVOM/GRM observation
  98. EP250226a/GRB 250226A: GSP detects optical counterpart
  99. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  100. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315

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