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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 231117A: Swift-XRT refined Analysis
  2. GRB 231118A: Swift-XRT refined Analysis
  3. GRB 231118A: MeerLICHT afterglow detection
  4. LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
  5. GRB 231117A: OHP/T120 optical observations
  6. GRB 231118A: VLT/X-shooter redshift
  7. Fermi trigger No 722039659: Global MASTER-Net observations report
  8. GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading
  9. LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
  10. GRB 231117A: MAAO 0.7-m telescope optical upper limit
  11. GRB 231117A: AKO Follow-Up Observation
  12. GRB 231117A: GECAM-C detection
  13. GRB 231118A: AstroSat CZTI detection
  14. GRB 231115A: Upper limit from CALET Gamma-Ray Burst Monitor
  15. GRB 231117A: 10 GHz VLA detection
  16. GRB 231118A: Las Cumbres optical detection
  17. GRB 231118B: BALROG localization (Fermi Trigger 722039659 / GRB 231118940)
  18. GRB 231118B: Fermi GBM Final Real-time Localization
  19. GRB 231118A: LCOGT Optical Observations
  20. GRB 231118A: MASTER OT observation
  21. GRB 231118A: Continued Skynet Observations
  22. Swift GRB231118.72: Global MASTER-Net observations report
  23. GRB 231118A: Enhanced Swift-XRT position
  24. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  25. GRB 231118A: Swift-XRT position
  26. GRB 231118A: Skynet Optical Afterglow Discovery
  27. GRB 231117A: SOAR/Goodman imaging of the afterglow
  28. GRB 231118A: Swift detection of a burst
  29. GRB 231118A: Fermi GBM Final Real-time Localization
  30. GRB 231117A: Lowell Discovery Telescope Observations
  31. GRB 231117A: ePESSTO+ host galaxy redshift confirmation
  32. GRB 231117A: ATCA detection of a radio counterpart
  33. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  34. GRB 231117A: GRBAlpha detection
  35. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  36. GRB 231117A: Keck spectroscopy of afterglow candidate
  37. GRB 231115A: Wendelstein Optical/Infrared Observations
  38. GRB 231115A: JinShan optical upper limits
  39. LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
  40. GRB 231117A: GIT optical follow-up
  41. GRB 231117A: LT observations consistent with fading
  42. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  43. GRB 231117A: REM optical and NIR early-time observations
  44. GRB231117A: AGILE/MCAL analysis
  45. GRB 231117A: AKO Optical Upper Limit
  46. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  47. Swift GRB 231117A: Global MASTER-Net observations report
  48. GRB 231117A (short): Glowbug gamma-ray detection
  49. GRB 231117A: ATLAS non-detection of an optical counterpart
  50. Konus-Wind detection of GRB 231117A (short/hard)
  51. GRB 231115A : OHP/T120 optical upper limit
  52. GRB 231115A: optical observations from INAF observatories
  53. GRB 231117A : MITSuME Akeno optical upper limits
  54. GRB 231117A: AGILE detection of a bright short burst
  55. GRB 231117A: Enhanced Swift-XRT position
  56. GRB 231117A: GOTO optical upper limits
  57. GRB 231117A: AstroSat CZTI detection of a bright short burst
  58. GRB 231117A: Swift detection of a bright short burst
  59. GRB 231115A: Non-detection of radio emission with CHIME/FRB
  60. GRB 231111A: Swift/UVOT Detection
  61. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  62. GRB231115A: Liverpool Telescope imaging
  63. GRB 231115A: NuSTAR Follow-Up Observations
  64. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  65. GRB 231115A: Swift-XRT and Swift-UVOT observations
  66. Fermi GRB 231116A: Global MASTER-Net observations report
  67. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  68. GRB 231115A: AGILE/MCAL upper limits
  69. GRB 231115A: Insight-HXMT/HE detection
  70. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  71. GRB 231116A: Fermi GBM Final Real-time Localization
  72. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  73. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  74. GRB 231115A / AT2023xvj: Updated GIT analysis
  75. GRB 231115A: archival Chandra X-ray observations
  76. GRB 231115A: Upper limits from a neutrino search with IceCube
  77. GRB 231115A: Kinder observations with Lulin observatory
  78. GRB231115A: GRANDMA Observations
  79. GRB 231115A: GOTO pre-burst limits of AT2023xvj
  80. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  81. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  82. GRB 231106A: TESS identification of candidate optical counterpart
  83. GRB 231115A: MASTER optical observations
  84. GRB 231115A (short): Glowbug gamma-ray detection
  85. GRB 231115A: Fermi Observations of a probable Magnetar Giant Flare from M82
  86. GRB 231115A: archival HST observations
  87. Integral GRB231115.65: Global MASTER-Net observations report
  88. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  89. GRB 231115A: Swift ToO observations
  90. Fermi GRB 231115A: Global MASTER-Net observations report
  91. GRB 231115A: significance of INTEGRAL localization alignment with M82
  92. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  93. GRB 231115A position consistent with M 82 galaxy
  94. GRB 231115A: Fermi GBM Final Real-time Localization
  95. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  96. GRB 231111A: Swift-BAT refined analysis
  97. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  98. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  99. Fermi GRB 231114A: Global MASTER-Net observations report
  100. GRB 231113A (short): Glowbug gamma-ray detection

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