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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"

36350 results found.

  1. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  2. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  3. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  4. GRB 250309B: PRIME near-infrared detection
  5. GRB 250225B: Swift-BAT refined analysis
  6. GRB 250311A/EP250311a: TRT optical upper limit
  7. GRB 250311A: Tiled Swift observations
  8. EP250311a/GRB 250311A: EP-WXT detection
  9. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 250311B: SVOM detection of a burst
  11. GRB 250309B: SVOM/VT optical observation
  12. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  13. GRB 250309B / AT2025dws: further SAO RAS optical observations
  14. IceCube-250309A: Upper limits from Fermi-GBM Observations
  15. Konus-Wind detection of GRB 250309B
  16. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  17. IPN triangulation of GRB 250308A (short)
  18. IPN triangulation of GRB 250309B
  19. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  20. GRB 250309B: Swift-XRT refined Analysis
  21. GRB 250309B / IceCube-250309A: GECAM-B observations
  22. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  23. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  24. GRB 250309B / AT2025dws: SAO RAS optical observations
  25. GRB 250309B / AT2025dws: Swift-UVOT detection
  26. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  27. GRB 250309B: Fermi GBM Observation
  28. Fermi GRB 250309B: Global MASTER-Net observations report
  29. Fermi GRB 250309A: Global MASTER-Net observations report
  30. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  31. Fermi-LAT gamma-ray observations of IceCube-250309A
  32. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  33. GRB 250309B: Fermi GBM Final Localization
  34. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  35. GRB 230509B: Tiled Swift observations
  36. GRB 250308A: SVOM/GRM observation of a bright short burst
  37. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  39. GRB 250309A: Fermi GBM Final Real-time Localization
  40. GRB 250306A: EIRSAT-1 GMOD detection
  41. Fermi GRB 250307A: Global MASTER-Net observations report
  42. Konus-Wind detection of GRB 250306A
  43. GRB 250307A: Fermi GBM Final Real-time Localization
  44. GRB 250306A: Swift-BAT refined analysis
  45. GRB 250306A: NuSTAR detection of the prompt emission
  46. GRB 250305A: AstroSat CZTI detection
  47. GRB 250306A: AstroSat CZTI detection
  48. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  49. Swift GRB 250306A: Global MASTER-Net observations report
  50. GRB 250306A: Swift detection of a burst
  51. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  52. GRB 250305A: SVOM/GRM observation of a burst
  53. EP250304A: Upper limits from Fermi-GBM Observations
  54. Fermi GRB 250305A: Global MASTER-Net observations report
  55. GRB 250305A: Fermi GBM Final Real-time Localization
  56. EP250302a: Optical Observations at CrAO and SAO RAS
  57. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  58. EP 250304A: Optical counterpart detection by LCO
  59. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  60. Konus-Wind detection of GRB 250222A
  61. IPN triangulation of GRB 250222A
  62. EP250302a: Mondy Continued Optical Observations
  63. EP250304a: VLT/X-shooter redshift z = 0.200
  64. EP250302a: NUTTelA-TAO Early Measurments
  65. EP250302a: Mondy Observations and Optical Light Curve
  66. EP250302a: OHP/T193 optical and spectroscopic observations
  67. GRB 250226A: GRANDMA Optical Observations
  68. EP250302a: Montarrenti Observatory optical detection
  69. Fermi GRB 250302A: Global MASTER-Net observations report
  70. GRB 250302A: Fermi GBM Final Real-time Localization
  71. GRB 250228A: Fermi GBM Final Localization
  72. GRB 250225B: VLT near-infrared afterglow confirmation
  73. Konus-Wind detection of GRB 250226A
  74. GRB 250225B: EIRSAT-1 GMOD Detection
  75. GRB 250226A: KAO Optical Upper Limit
  76. GRB 250226A: AbAO AS-32 Optical Upper Limit
  77. EP250223A: Upper limits from Fermi-GBM Observations
  78. GRB 250225B: VLT/HAWKI near-infrared observations
  79. GRB 250226A: Fermi GBM Observation
  80. GRB 250226A / EP250226a: LCO detection of the afterglow
  81. GRB 250225B: VLT/Xshooter imaging
  82. GRB 250205A / EP250205A: further radio observations with the VLA
  83. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  84. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  85. GRB 250225B: INTEGRAL SPI-ACS detection
  86. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  87. EP250226a / GRB 250226A: SVOM/VT optical observations
  88. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  89. EP250226a/GRB 250226A: 1.6m Mephisto observations
  90. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  91. EP250226a/GRB 250226A: Kinder optical follow-up observations
  92. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  93. Fermi GRB 250226B: Global MASTER-Net observations report
  94. GRB 250226B: Fermi GBM Final Real-time Localization
  95. GRB 250225B: Fermi GBM Observation
  96. GRB 250221A: ATCA Detections and Upper Limits
  97. GRB 250225B: REM NIR upper limits
  98. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  99. Konus-Wind detection of GRB 250225B
  100. EP250223a: CrAO ZTSH optical observation

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