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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').
  1. GRB 231114A (short): Glowbug gamma-ray detection
  2. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  3. GECAM-B observation of a short burst from SGR J1555-5402
  4. GRB 231114A: Fermi GBM Final Localization
  5. LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
  6. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  7. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  8. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  9. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  10. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  11. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  12. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  13. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  14. GRB 231110A: Swift-BAT refined analysis
  15. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  16. GRB 231106A: Glowbug gamma-ray detection
  17. GRB 231111A: Xinglong-2.16m optical observations
  18. GRB 231110A: Swift-UVOT Upper Limits
  19. LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
  20. GRB 231111A: Afterglow redshift from OSIRIS+/GTC
  21. GRB 231104A: VZLUSAT-2 detection
  22. GRB 231111A: TNG tentative redshift
  23. GRB 231110A: Glowbug gamma-ray detection
  24. GRB 231110A: AstroSat CZTI detection
  25. GRB 231111A NUTTelA-TAO / BSTI Early Measurements
  26. GRB 231111A: Leavitt Observatory optical observations
  27. GRB231111A: Optical follow-up observations with Mephisto
  28. GRB 231111A: GMG observation (correction)
  29. LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
  30. GRB 231111A: GMG observation upper limit
  31. GRB 231106B: GRBAlpha detection
  32. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  33. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  34. GRB 231111A: Swift-XRT refined Analysis
  35. GRB 231111A: Mondy optical observations
  36. GRB 231111A: GECAM-C detection of a long burst (correction)
  37. GRB 231110A: GECAM-B detection (correction)
  38. GRB 231111A: Enhanced Swift-XRT position
  39. GRB 231111A: GECAM-C detection of a long burst
  40. GRB 231110A: GECAM detection
  41. GRB 231110A: GOTO optical upper limits
  42. GRB 231110A: SAO RAS optical observations
  43. GRB 231110A: Swift-XRT afterglow detection
  44. GRB231111A: YAHPT Observations
  45. GRB231111A: GIT confirmation of the optical afterglow
  46. GRB 231111A: MASTER OT earlier detection
  47. GRB 231111A: Nanshan/HMT optical observations
  48. GRB 231111A: Swift detection of a burst with an optical counterpart
  49. Swift GRB231111.60: Global MASTER-Net observations report
  50. GRB231110A: WFST Observation and upper limits
  51. Swift GRB231110.89: Global MASTER-Net observations report
  52. GRB 231110A: Swift detection of a burst
  53. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  54. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  55. GRB 231109A: Fermi GBM Final Localization
  56. IceCube-231103A: No candidates from the Zwicky Transient Facility
  57. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  58. Fermi trigger No 721204446: Global MASTER-Net observations report
  59. Fermi GRB 231108A: Global MASTER-Net observations report
  60. GRB 231108A: Fermi GBM Final Real-time Localization
  61. LIGO/Virgo/KAGRA O4 Landscape
  62. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  63. GRB 231106A: AstroSat CZTI detection
  64. GRB 231106A: CALET Gamma-Ray Burst Monitor detection
  65. GRB 231104A: Swift-BAT refined analysis
  66. Fermi trigger No 721006392: Global MASTER-Net observations report
  67. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  68. GRB 231104A: FRAM-ORM optical limit
  69. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  70. Fermi GRB 231106A: Global MASTER-Net observations report
  71. GRB 231104A: Wendelstein Optical/Infrared Observations
  72. GRB 231104A: NuSTAR Observation of the prompt emission
  73. GRB 231106A: Fermi GBM Final Real-time Localization
  74. GRB 231104A: 3.6m DOT optical upper limit
  75. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  76. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  77. Fermi-LAT gamma-ray observations of IceCube-231103A
  78. GRB 231104A: NOT upper limit
  79. GRB 231104A: Fermi GBM Observation
  80. GRB 231104B: Fermi GBM Final Real-time Localization
  81. Fermi GRB 231103A: Global MASTER-Net observations report
  82. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  83. GRB 231104A: AKO Upper Limit
  84. GRB 231104A: AstroSat CZTI detection
  85. GRB 231104A: Swift-XRT refined Analysis
  86. GRB 231104A: Fermi-LAT detection
  87. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  88. GRB 231104A: Swift/UVOT Upper Limits
  89. GRB 231104A: Enhanced Swift-XRT position
  90. GRB231104A: LCOGT Optical Upper Limits
  91. GRB 231104A: Swift detection of a bright burst
  92. GRB 231104A: Fermi GBM Final Real-time Localization
  93. Swift GRB231104.07: Global MASTER-Net observations report
  94. IceCube Alert 231103.39: Global MASTER-Net observations report
  95. GRB 231103A: Fermi GBM Final Real-time Localization
  96. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  97. Fermi-LAT gamma-ray observations of IceCube-231027A
  98. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  99. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  100. GRB 231101A: Glowbug gamma-ray detection


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