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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"

45776 results found.

  1. EP250302a: Chandra X-ray Detection
  2. GRB 250312A: Swift-XRT refined Analysis
  3. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  4. Fermi trigger No 763509110: Global MASTER-Net observations report
  5. Fermi GRB 250312B: Global MASTER-Net observations report
  6. GRB 250312A: Enhanced Swift-XRT position
  7. GRB 250312B: Fermi GBM Final Localization
  8. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  9. GRB 250226B: Fermi GBM Observation
  10. Swift GRB 250312A: Global MASTER-Net observations report
  11. GRB 250302A: Fermi GBM Observation
  12. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  13. GRB 250312A: Swift detection of a burst
  14. GRB 241213A: VIRT Optical Upper Limit
  15. GRB 241228A: VIRT Optical Upper Limit
  16. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  17. GRB 250223B: Fermi GBM Observation
  18. GRB 250311A: Swift-XRT observations
  19. GRB 250228A: Fermi GBM Observation
  20. GRB 250309B: 1.3m DFOT Optical observations
  21. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  22. EP250311a: Global MASTER-Net observations report
  23. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  24. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  25. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  26. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  27. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  28. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  29. GRB 250309B: PRIME near-infrared detection
  30. EP250304a: Chandra detection
  31. GRB 250225B: Swift-BAT refined analysis
  32. GRB 250311A/EP250311a: TRT optical upper limit
  33. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  34. GRB 250311A: Tiled Swift observations
  35. EP250311a/GRB 250311A: EP-WXT detection
  36. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  37. GRB 250311B: SVOM detection of a burst
  38. GRB 250309B: SVOM/VT optical observation
  39. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  40. The EP-WXT trigger 01709132425 is not a real source
  41. GRB 250309B / AT2025dws: further SAO RAS optical observations
  42. IceCube-250309A: Upper limits from Fermi-GBM Observations
  43. EP250308a: 1.6m Mephisto optical upper limits
  44. Konus-Wind detection of GRB 250309B
  45. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  46. IPN triangulation of GRB 250308A (short)
  47. IPN triangulation of GRB 250309B
  48. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  49. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  50. GRB 250309B: Swift-XRT refined Analysis
  51. GRB 250309B / IceCube-250309A: GECAM-B observations
  52. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  53. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  54. GRB 250309B / AT2025dws: SAO RAS optical observations
  55. GRB 250309B / AT2025dws: Swift-UVOT detection
  56. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  57. GRB 250309B: Fermi GBM Observation
  58. Fermi GRB 250309B: Global MASTER-Net observations report
  59. Fermi GRB 250309A: Global MASTER-Net observations report
  60. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  61. IceCube-250309A: No candidates from the Zwicky Transient Facility
  62. Fermi-LAT gamma-ray observations of IceCube-250309A
  63. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  64. GRB 250309B: Fermi GBM Final Localization
  65. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  66. GRB 230509B: Tiled Swift observations
  67. GRB 250308A: SVOM/GRM observation of a bright short burst
  68. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  69. IceCube Alert 250309.32: Global MASTER-Net observations report
  70. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  71. EP250308a: Global MASTER-Net observations report
  72. EP250308a: GSP optical upper limit
  73. EP250308a: FTW optical and NIR upper limits
  74. EP250308a: Einstein Probe detection of an X-ray transient
  75. EP250308a: NOT optical upper limit
  76. GRB 250309A: Fermi GBM Final Real-time Localization
  77. GRB 250306A: EIRSAT-1 GMOD detection
  78. The EP-WXT trigger 01709132387 is likely a flaring star
  79. Fermi GRB 250307A: Global MASTER-Net observations report
  80. Konus-Wind detection of GRB 250306A
  81. GRB 250307A: Fermi GBM Final Real-time Localization
  82. GRB 250306A: Swift-BAT refined analysis
  83. GRB 250306A: NuSTAR detection of the prompt emission
  84. EP250304a: MeerKAT detection of a possible radio counterpart
  85. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  86. GRB 250305A: AstroSat CZTI detection
  87. EP250302a:Xinglong optical observations
  88. GRB 250306A: AstroSat CZTI detection
  89. Fermi trigger No 762963055: Global MASTER-Net observations report
  90. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  91. Swift GRB 250306A: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  93. GRB 250306A: Swift detection of a burst
  94. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  95. GRB250101A: Radio upper limits from VLA observations
  96. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  97. GRB 250305A: SVOM/GRM observation of a burst
  98. The EP-WXT trigger 01709132323 is likely a flaring star
  99. EP250304A: Upper limits from Fermi-GBM Observations
  100. Fermi GRB 250305A: Global MASTER-Net observations report

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