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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"

36344 results found.

  1. EP250311a/GRB 250311A: EP-WXT detection
  2. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  3. GRB 250311B: SVOM detection of a burst
  4. GRB 250309B: SVOM/VT optical observation
  5. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  6. GRB 250309B / AT2025dws: further SAO RAS optical observations
  7. IceCube-250309A: Upper limits from Fermi-GBM Observations
  8. Konus-Wind detection of GRB 250309B
  9. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  10. IPN triangulation of GRB 250308A (short)
  11. IPN triangulation of GRB 250309B
  12. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  13. GRB 250309B: Swift-XRT refined Analysis
  14. GRB 250309B / IceCube-250309A: GECAM-B observations
  15. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  16. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  17. GRB 250309B / AT2025dws: SAO RAS optical observations
  18. GRB 250309B / AT2025dws: Swift-UVOT detection
  19. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  20. GRB 250309B: Fermi GBM Observation
  21. Fermi GRB 250309B: Global MASTER-Net observations report
  22. Fermi GRB 250309A: Global MASTER-Net observations report
  23. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  24. Fermi-LAT gamma-ray observations of IceCube-250309A
  25. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  26. GRB 250309B: Fermi GBM Final Localization
  27. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  28. GRB 230509B: Tiled Swift observations
  29. GRB 250308A: SVOM/GRM observation of a bright short burst
  30. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  31. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  32. GRB 250309A: Fermi GBM Final Real-time Localization
  33. GRB 250306A: EIRSAT-1 GMOD detection
  34. Fermi GRB 250307A: Global MASTER-Net observations report
  35. Konus-Wind detection of GRB 250306A
  36. GRB 250307A: Fermi GBM Final Real-time Localization
  37. GRB 250306A: Swift-BAT refined analysis
  38. GRB 250306A: NuSTAR detection of the prompt emission
  39. GRB 250305A: AstroSat CZTI detection
  40. GRB 250306A: AstroSat CZTI detection
  41. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  42. Swift GRB 250306A: Global MASTER-Net observations report
  43. GRB 250306A: Swift detection of a burst
  44. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  45. GRB 250305A: SVOM/GRM observation of a burst
  46. EP250304A: Upper limits from Fermi-GBM Observations
  47. Fermi GRB 250305A: Global MASTER-Net observations report
  48. GRB 250305A: Fermi GBM Final Real-time Localization
  49. EP250302a: Optical Observations at CrAO and SAO RAS
  50. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  51. EP 250304A: Optical counterpart detection by LCO
  52. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  53. Konus-Wind detection of GRB 250222A
  54. IPN triangulation of GRB 250222A
  55. EP250302a: Mondy Continued Optical Observations
  56. EP250304a: VLT/X-shooter redshift z = 0.200
  57. EP250302a: NUTTelA-TAO Early Measurments
  58. EP250302a: Mondy Observations and Optical Light Curve
  59. EP250302a: OHP/T193 optical and spectroscopic observations
  60. GRB 250226A: GRANDMA Optical Observations
  61. EP250302a: Montarrenti Observatory optical detection
  62. Fermi GRB 250302A: Global MASTER-Net observations report
  63. GRB 250302A: Fermi GBM Final Real-time Localization
  64. GRB 250228A: Fermi GBM Final Localization
  65. GRB 250225B: VLT near-infrared afterglow confirmation
  66. Konus-Wind detection of GRB 250226A
  67. GRB 250225B: EIRSAT-1 GMOD Detection
  68. GRB 250226A: KAO Optical Upper Limit
  69. GRB 250226A: AbAO AS-32 Optical Upper Limit
  70. EP250223A: Upper limits from Fermi-GBM Observations
  71. GRB 250225B: VLT/HAWKI near-infrared observations
  72. GRB 250226A: Fermi GBM Observation
  73. GRB 250226A / EP250226a: LCO detection of the afterglow
  74. GRB 250225B: VLT/Xshooter imaging
  75. GRB 250205A / EP250205A: further radio observations with the VLA
  76. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  77. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  78. GRB 250225B: INTEGRAL SPI-ACS detection
  79. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  80. EP250226a / GRB 250226A: SVOM/VT optical observations
  81. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  82. EP250226a/GRB 250226A: 1.6m Mephisto observations
  83. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  84. EP250226a/GRB 250226A: Kinder optical follow-up observations
  85. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  86. Fermi GRB 250226B: Global MASTER-Net observations report
  87. GRB 250226B: Fermi GBM Final Real-time Localization
  88. GRB 250225B: Fermi GBM Observation
  89. GRB 250221A: ATCA Detections and Upper Limits
  90. GRB 250225B: REM NIR upper limits
  91. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  92. Konus-Wind detection of GRB 250225B
  93. EP250223a: CrAO ZTSH optical observation
  94. GRB 250225B: VLT optical and near-infrared candidate counterpart
  95. GRB 250225B: VLT/FORS2 candidate optical afterglow
  96. GRB 250225B: SVOM/GRM observation of a long burst
  97. GRB 250226A: GECAM-B detection
  98. GRB 250221A: EP-FXT detection of the X-ray afterglow
  99. GRB 250214A: SVOM/GRM observation
  100. EP250226a/GRB 250226A: GSP detects optical counterpart

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