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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"
  1. GRB 231125A: AstroSat CZTI detection of a short burst
  2. GRB 231111A: Optical follow-up observations at Terskol, AbAO, Maidanak, Mondy, Assy
  3. GRB 231126A: Fermi GBM Final Real-time Localization
  4. GRB 231123C: Insight-HXMT/HE detection
  5. Fermi trigger No 722460326: Global MASTER-Net observations report
  6. Fermi trigger No 722507896: Global MASTER-Net observations report
  7. GRB 231123C (short): Glowbug gamma-ray detection
  8. GRB 231124A: Glowbug gamma-ray detection
  9. GRB230728A: VIRT optical upper limit
  10. GRB230506C: VIRT optical upper limit
  11. GRB230506B: VIRT optical upper limit
  12. GRB 231123C: Swift/BAT-GUANO detection of a short burst likely outside the coded FOV
  13. Fermi trigger No 722462310: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S231118an: Updated Sky localization and EM Bright Classification
  15. GRB 231124A: CALET Gamma-Ray Burst Monitor detection
  16. GRB 231115A: XMM-Newton observation
  17. GRB 231124A: Fermi GBM Final Real-time Localization
  18. GRB 231123A: AstroSat CZTI detection
  19. GRB 231117A: Mondy optical observations
  20. GRB 231123C: Fermi GBM Final Real-time Localization
  21. GRB 231123B: Fermi GBM Final Real-time Localization
  22. Fermi trigger No 722400249: Global MASTER-Net observations report
  23. LIGO/Virgo/KAGRA S231123cg: Identification of a GW compact binary merger candidate
  24. GRB 231118A: REM optical afterglow detection
  25. GRB 231122B: AstroSat CZTI detection
  26. GRB 231122B: CALET Gamma-Ray Burst Monitor detection
  27. GRB 231122B: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  28. GRB 231117A: Chandra afterglow detection
  29. GRB 231123A: Fermi GBM Final Real-time Localization
  30. GRB 231122B: Glowbug gamma-ray detection
  31. GRB 231117A: Continued GTC Observations
  32. Fermi trigger No 722349867: Global MASTER-Net observations report
  33. GRB 231122A: GECAM detection
  34. GRB 231122B: GECAM detection
  35. GRB 231122A: Fermi GBM Final Real-time Localization
  36. GRB 231118A: ATCA detection of radio counterpart
  37. GRB 231117A: Swift/UVOT late time observations
  38. GRB 231117A: GTC Near-Infrared Observations
  39. GRB 231117A: Swift-BAT refined analysis
  40. GRB 231118A: GRBAlpha detection
  41. LIGO/Virgo/KAGRA S231118d: Upper limits from Swift/BAT-GUANO
  42. LIGO/Virgo/KAGRA S231118an: Upper limits from Swift/BAT-GUANO
  43. LIGO/Virgo/KAGRA S231114n: Upper limits from Swift/BAT-GUANO
  44. LIGO/Virgo/KAGRA S231113bb: Upper limits from Swift/BAT-GUANO
  45. LIGO/Virgo/KAGRA S231119u: Updated Sky localization and Source Classification
  46. LIGO/Virgo/KAGRA S231118ab: Updated Sky localization and Source Classification
  47. LIGO/Virgo/KAGRA S231118d: Updated Sky localization and Source Classification
  48. GRB 231118A: VZLUSAT-2 detection
  49. GRB 231117A: AMI-LA radio observations
  50. GRB 231118A: Swift-BAT refined analysis
  51. Konus-Wind detection of GRB 231020A
  52. GRB 231117A: LDT Confirmation of Optical Fading
  53. GRB 231117A: Wendelstein Confirmation of Fading of the Optical Afterglow
  54. GRB 231118B: CALET Gamma-Ray Burst Monitor detection
  55. GRB 231117A: CALET Gamma-Ray Burst Monitor detection
  56. 231118A: Swift-UVOT Detection
  57. GRB231117A: Swift-UVOT detection
  58. GRB 231117A : MITSuME Akeno optical afterglow candidate detection
  59. GRB 231118B: Fermi GBM observation
  60. GRB 231118A: Fermi GBM observation
  61. LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
  62. GRB 231120A: Fermi GBM Final Real-time Localization
  63. GRB 231117A: Swift-XRT refined Analysis
  64. GRB 231118A: Swift-XRT refined Analysis
  65. GRB 231118A: MeerLICHT afterglow detection
  66. LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
  67. GRB 231117A: OHP/T120 optical observations
  68. GRB 231118A: VLT/X-shooter redshift
  69. Fermi trigger No 722039659: Global MASTER-Net observations report
  70. GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading
  71. LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
  72. GRB 231117A: MAAO 0.7-m telescope optical upper limit
  73. GRB 231117A: AKO Follow-Up Observation
  74. GRB 231117A: GECAM-C detection
  75. GRB 231118A: AstroSat CZTI detection
  76. GRB 231115A: Upper limit from CALET Gamma-Ray Burst Monitor
  77. GRB 231117A: 10 GHz VLA detection
  78. GRB 231118A: Las Cumbres optical detection
  79. GRB 231118B: BALROG localization (Fermi Trigger 722039659 / GRB 231118940)
  80. GRB 231118B: Fermi GBM Final Real-time Localization
  81. GRB 231118A: LCOGT Optical Observations
  82. GRB 231118A: MASTER OT observation
  83. GRB 231118A: Continued Skynet Observations
  84. Swift GRB231118.72: Global MASTER-Net observations report
  85. GRB 231118A: Enhanced Swift-XRT position
  86. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  87. GRB 231118A: Swift-XRT position
  88. GRB 231118A: Skynet Optical Afterglow Discovery
  89. GRB 231117A: SOAR/Goodman imaging of the afterglow
  90. GRB 231118A: Swift detection of a burst
  91. GRB 231118A: Fermi GBM Final Real-time Localization
  92. GRB 231117A: Lowell Discovery Telescope Observations
  93. GRB 231117A: ePESSTO+ host galaxy redshift confirmation
  94. GRB 231117A: ATCA detection of a radio counterpart
  95. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  96. GRB 231117A: GRBAlpha detection
  97. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  98. GRB 231117A: Keck spectroscopy of afterglow candidate
  99. GRB 231115A: Wendelstein Optical/Infrared Observations
  100. GRB 231115A: JinShan optical upper limits

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