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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"
  1. GRB 240125A: AstroSat CZTI detection of a short burst
  2. GRB 240124B: AstroSat CZTI detection
  3. GRB 240123C: AstroSat CZTI detection
  4. GRB 240125B: Fermi GBM Final Localization
  5. GRB240122A: PRIME near infrared detection
  6. GRB 240123B: Fermi GBM Observation
  7. GRB 240123A: Glowbug gamma-ray detection
  8. GRB 240125A (short): Glowbug gamma-ray detection
  9. GRB 240123B: Swift/BAT-GUANO detection of a long burst
  10. GRB 240123A: GRBAlpha detection
  11. IPN triangulation of GRB 240123C (short)
  12. Swift trigger 1210856 is not astrophysical
  13. Fermi-LAT gamma-ray observations of IceCube-240123A
  14. GRB 240123A: further SAO RAS optical observations
  15. GRB 240122B: CALET Gamma-Ray Burst Monitor detection
  16. GRB 240123A: Swift-BAT refined analysis
  17. IceCube Alert 240123.48: Global MASTER-Net observations report
  18. GRB 240123A: Mondy continued optical observations and the PL decay index
  19. GRB 240123A: SAO RAS optical observations
  20. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  21. Fermi/GBM trigger 727752941: BALROG analysis retraction
  22. GRB 240123A: Enhanced Swift-XRT position
  23. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  24. Fermi GRB 240123B: Global MASTER-Net observations report
  25. GRB 240122A: Swift/UVOT Upper Limits
  26. GRB 240123A: Swift-XRT refined Analysis
  27. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  28. Fermi GBM Sub-Threshold Detection of GRB 240123A
  29. GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
  30. GRB 240123B: Fermi GBM Final Real-time Localization
  31. GRB 240118A: Swift/UVOT Upper Limits
  32. GRB 240122B: Glowbug gamma-ray detection
  33. GRB 240123A: Mondy optical afterglow observations
  34. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  35. Konus-Wind detection of GRB 240112A
  36. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  37. Swift GRB240123.46: Global MASTER-Net observations report
  38. GRB 240122A: Swift-XRT afterglow detection
  39. GRB 240122A: VLT/X-shooter redshift confirmation
  40. GRB 240122A: Redshift from OSIRIS+/GTC
  41. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  42. GRB 240122A: GOTO optical counterpart candidate
  43. GRB 240122A: Tiled Swift observations
  44. Konus-Wind detection of GRB 240119A (short/hard)
  45. GRB 240122A: MAXI/GSC detection
  46. IPN triangulation of GRB 240119A (short)
  47. GRB 240119A: GECAM detection of a short burst
  48. GRB 240118C: GECAM-B detection of a long burst
  49. GRB 240119A: AstroSat CZTI detection of a short burst
  50. GRB 240118A: Mondy optical observations
  51. GRB 240118A: Swift-XRT afterglow detection
  52. GRB 240118C: Fermi GBM Observation
  53. Fermi GRB 240119A: Global MASTER-Net observations report
  54. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  55. GRB 240119A: Fermi GBM Final Localization
  56. GRB 240117A: CALET Gamma-Ray Burst Monitor detection
  57. GRB 240118C: Swift/BAT-GUANO detection of a burst
  58. GRB 240118A: GRBAlpha detection
  59. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A: correction on the localization
  60. GRB 240115A: Fermi GBM Observation
  61. Swift triggers 1209631, 1209632, 1209635 and 1209644 are not interesting astrophysical events
  62. GRB 240118C: Fermi GBM Final Localization
  63. GRB 240118D: AstroSat CZTI detection
  64. GRB 240117A: AstroSat CZTI detection
  65. GRB 240118A: Swift ToO observations
  66. GRB 240118A: AbAO optical upper limit
  67. Fermi GRB 240118B: Global MASTER-Net observations report
  68. GRB 240118A: NuSTAR Offline Analysis of the GRB
  69. GRB 240117A: Glowbug gamma-ray detection
  70. GRB 240118A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  71. Konus-Wind detection of GRB 240118A
  72. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A
  73. GRB 240118C: BALROG localization (Fermi Trigger 727291408 / GRB 240118725)
  74. GRB 240118A: NuSTAR Detection of a Long GRB
  75. GRB 240118A: Fermi GBM Observation
  76. GRB 240118B: Fermi GBM Final Real-time Localization
  77. LAT GRB240118.08: Global MASTER-Net observations report
  78. GRB 240118A: Fermi-LAT detection
  79. GRID detection of GRB 231230A
  80. GRB 240118A: Fermi GBM Final Real-time Localization
  81. GRB 240115A: Swift/BAT-GUANO detection of a short burst
  82. Swift Trigger 1209406 is not an astrophysical event
  83. Swift Triggers 1209401 and 1209403 are not astrophysical events
  84. IPN triangulation of GRB 240112A (long)
  85. Swift Triggers 1209371 through 1209374 are not astrophysical events
  86. Swift Triggers 1209369 and 1209370 are not astrophysical events
  87. GRB 240115B: AstroSat CZTI detection
  88. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  89. GRB 240115B: Fermi GBM Detection
  90. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  91. GRB 240112D: Glowbug gamma-ray detection
  92. GRB 240112C: Glowbug gamma-ray detection
  93. GRB 240112C: VZLUSAT-2 detection
  94. GRB 240107A: VZLUSAT-2 detection
  95. Integral GRB240115.70: Global MASTER-Net observations report
  96. Fermi GRB 240115B: Global MASTER-Net observations report
  97. GRB 240115B: A long GRB detected by INTEGRAL
  98. GRB 240115B: Fermi GBM Final Real-time Localization
  99. Konus-Wind detection of GRB 240112C
  100. Fermi GRB 240115A: Global MASTER-Net observations report

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