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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: 10 GHz VLA detection
  2. GRB 231118A: Las Cumbres optical detection
  3. GRB 231118B: BALROG localization (Fermi Trigger 722039659 / GRB 231118940)
  4. GRB 231118B: Fermi GBM Final Real-time Localization
  5. GRB 231118A: LCOGT Optical Observations
  6. GRB 231118A: MASTER OT observation
  7. GRB 231118A: Continued Skynet Observations
  8. Swift GRB231118.72: Global MASTER-Net observations report
  9. GRB 231118A: Enhanced Swift-XRT position
  10. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  11. GRB 231118A: Swift-XRT position
  12. GRB 231118A: Skynet Optical Afterglow Discovery
  13. GRB 231117A: SOAR/Goodman imaging of the afterglow
  14. GRB 231118A: Swift detection of a burst
  15. GRB 231118A: Fermi GBM Final Real-time Localization
  16. GRB 231117A: Lowell Discovery Telescope Observations
  17. GRB 231117A: ePESSTO+ host galaxy redshift confirmation
  18. GRB 231117A: ATCA detection of a radio counterpart
  19. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  20. GRB 231117A: GRBAlpha detection
  21. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  22. GRB 231117A: Keck spectroscopy of afterglow candidate
  23. GRB 231115A: Wendelstein Optical/Infrared Observations
  24. GRB 231115A: JinShan optical upper limits
  25. LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
  26. GRB 231117A: GIT optical follow-up
  27. GRB 231117A: LT observations consistent with fading
  28. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  29. GRB 231117A: REM optical and NIR early-time observations
  30. GRB231117A: AGILE/MCAL analysis
  31. GRB 231117A: AKO Optical Upper Limit
  32. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  33. Swift GRB 231117A: Global MASTER-Net observations report
  34. GRB 231117A (short): Glowbug gamma-ray detection
  35. GRB 231117A: ATLAS non-detection of an optical counterpart
  36. Konus-Wind detection of GRB 231117A (short/hard)
  37. GRB 231115A : OHP/T120 optical upper limit
  38. GRB 231115A: optical observations from INAF observatories
  39. GRB 231117A : MITSuME Akeno optical upper limits
  40. GRB 231117A: AGILE detection of a bright short burst
  41. GRB 231117A: Enhanced Swift-XRT position
  42. GRB 231117A: GOTO optical upper limits
  43. GRB 231117A: AstroSat CZTI detection of a bright short burst
  44. GRB 231117A: Swift detection of a bright short burst
  45. GRB 231115A: Non-detection of radio emission with CHIME/FRB
  46. GRB 231111A: Swift/UVOT Detection
  47. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  48. GRB231115A: Liverpool Telescope imaging
  49. GRB 231115A: NuSTAR Follow-Up Observations
  50. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  51. GRB 231115A: Swift-XRT and Swift-UVOT observations
  52. Fermi GRB 231116A: Global MASTER-Net observations report
  53. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  54. GRB 231115A: AGILE/MCAL upper limits
  55. GRB 231115A: Insight-HXMT/HE detection
  56. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  57. GRB 231116A: Fermi GBM Final Real-time Localization
  58. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  59. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  60. GRB 231115A / AT2023xvj: Updated GIT analysis
  61. GRB 231115A: archival Chandra X-ray observations
  62. GRB 231115A: Upper limits from a neutrino search with IceCube
  63. GRB 231115A: Kinder observations with Lulin observatory
  64. GRB231115A: GRANDMA Observations
  65. GRB 231115A: GOTO pre-burst limits of AT2023xvj
  66. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  67. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  68. GRB 231106A: TESS identification of candidate optical counterpart
  69. GRB 231115A: MASTER optical observations
  70. GRB 231115A (short): Glowbug gamma-ray detection
  71. GRB 231115A: Fermi Observations of a probable Magnetar Giant Flare from M82
  72. GRB 231115A: archival HST observations
  73. Integral GRB231115.65: Global MASTER-Net observations report
  74. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  75. GRB 231115A: Swift ToO observations
  76. Fermi GRB 231115A: Global MASTER-Net observations report
  77. GRB 231115A: significance of INTEGRAL localization alignment with M82
  78. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  79. GRB 231115A position consistent with M 82 galaxy
  80. GRB 231115A: Fermi GBM Final Real-time Localization
  81. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  82. GRB 231111A: Swift-BAT refined analysis
  83. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  84. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  85. Fermi GRB 231114A: Global MASTER-Net observations report
  86. GRB 231113A (short): Glowbug gamma-ray detection
  87. GRB 231114A (short): Glowbug gamma-ray detection
  88. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  89. GECAM-B observation of a short burst from SGR J1555-5402
  90. GRB 231114A: Fermi GBM Final Localization
  91. LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
  92. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  93. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  94. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  95. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  96. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  97. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  98. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  99. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  100. GRB 231110A: Swift-BAT refined analysis

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