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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 231117A: Swift-BAT refined analysis
  2. GRB 231118A: GRBAlpha detection
  3. LIGO/Virgo/KAGRA S231118d: Upper limits from Swift/BAT-GUANO
  4. LIGO/Virgo/KAGRA S231118an: Upper limits from Swift/BAT-GUANO
  5. LIGO/Virgo/KAGRA S231114n: Upper limits from Swift/BAT-GUANO
  6. LIGO/Virgo/KAGRA S231113bb: Upper limits from Swift/BAT-GUANO
  7. LIGO/Virgo/KAGRA S231119u: Updated Sky localization and Source Classification
  8. LIGO/Virgo/KAGRA S231118ab: Updated Sky localization and Source Classification
  9. LIGO/Virgo/KAGRA S231118d: Updated Sky localization and Source Classification
  10. GRB 231118A: VZLUSAT-2 detection
  11. GRB 231117A: AMI-LA radio observations
  12. GRB 231118A: Swift-BAT refined analysis
  13. Konus-Wind detection of GRB 231020A
  14. GRB 231117A: LDT Confirmation of Optical Fading
  15. GRB 231117A: Wendelstein Confirmation of Fading of the Optical Afterglow
  16. GRB 231118B: CALET Gamma-Ray Burst Monitor detection
  17. GRB 231117A: CALET Gamma-Ray Burst Monitor detection
  18. 231118A: Swift-UVOT Detection
  19. GRB231117A: Swift-UVOT detection
  20. GRB 231117A : MITSuME Akeno optical afterglow candidate detection
  21. GRB 231118B: Fermi GBM observation
  22. GRB 231118A: Fermi GBM observation
  23. LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
  24. GRB 231120A: Fermi GBM Final Real-time Localization
  25. GRB 231117A: Swift-XRT refined Analysis
  26. GRB 231118A: Swift-XRT refined Analysis
  27. GRB 231118A: MeerLICHT afterglow detection
  28. LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
  29. GRB 231117A: OHP/T120 optical observations
  30. GRB 231118A: VLT/X-shooter redshift
  31. Fermi trigger No 722039659: Global MASTER-Net observations report
  32. GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading
  33. LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
  34. GRB 231117A: MAAO 0.7-m telescope optical upper limit
  35. GRB 231117A: AKO Follow-Up Observation
  36. GRB 231117A: GECAM-C detection
  37. GRB 231118A: AstroSat CZTI detection
  38. GRB 231115A: Upper limit from CALET Gamma-Ray Burst Monitor
  39. GRB 231117A: 10 GHz VLA detection
  40. GRB 231118A: Las Cumbres optical detection
  41. GRB 231118B: BALROG localization (Fermi Trigger 722039659 / GRB 231118940)
  42. GRB 231118B: Fermi GBM Final Real-time Localization
  43. GRB 231118A: LCOGT Optical Observations
  44. GRB 231118A: MASTER OT observation
  45. GRB 231118A: Continued Skynet Observations
  46. Swift GRB231118.72: Global MASTER-Net observations report
  47. GRB 231118A: Enhanced Swift-XRT position
  48. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  49. GRB 231118A: Swift-XRT position
  50. GRB 231118A: Skynet Optical Afterglow Discovery
  51. GRB 231117A: SOAR/Goodman imaging of the afterglow
  52. GRB 231118A: Swift detection of a burst
  53. GRB 231118A: Fermi GBM Final Real-time Localization
  54. GRB 231117A: Lowell Discovery Telescope Observations
  55. GRB 231117A: ePESSTO+ host galaxy redshift confirmation
  56. GRB 231117A: ATCA detection of a radio counterpart
  57. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  58. GRB 231117A: GRBAlpha detection
  59. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  60. GRB 231117A: Keck spectroscopy of afterglow candidate
  61. GRB 231115A: Wendelstein Optical/Infrared Observations
  62. GRB 231115A: JinShan optical upper limits
  63. LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
  64. GRB 231117A: GIT optical follow-up
  65. GRB 231117A: LT observations consistent with fading
  66. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  67. GRB 231117A: REM optical and NIR early-time observations
  68. GRB231117A: AGILE/MCAL analysis
  69. GRB 231117A: AKO Optical Upper Limit
  70. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  71. Swift GRB 231117A: Global MASTER-Net observations report
  72. GRB 231117A (short): Glowbug gamma-ray detection
  73. GRB 231117A: ATLAS non-detection of an optical counterpart
  74. Konus-Wind detection of GRB 231117A (short/hard)
  75. GRB 231115A : OHP/T120 optical upper limit
  76. GRB 231115A: optical observations from INAF observatories
  77. GRB 231117A : MITSuME Akeno optical upper limits
  78. GRB 231117A: AGILE detection of a bright short burst
  79. GRB 231117A: Enhanced Swift-XRT position
  80. GRB 231117A: GOTO optical upper limits
  81. GRB 231117A: AstroSat CZTI detection of a bright short burst
  82. GRB 231117A: Swift detection of a bright short burst
  83. GRB 231115A: Non-detection of radio emission with CHIME/FRB
  84. GRB 231111A: Swift/UVOT Detection
  85. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  86. GRB231115A: Liverpool Telescope imaging
  87. GRB 231115A: NuSTAR Follow-Up Observations
  88. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  89. GRB 231115A: Swift-XRT and Swift-UVOT observations
  90. Fermi GRB 231116A: Global MASTER-Net observations report
  91. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  92. GRB 231115A: AGILE/MCAL upper limits
  93. GRB 231115A: Insight-HXMT/HE detection
  94. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  95. GRB 231116A: Fermi GBM Final Real-time Localization
  96. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  97. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  98. GRB 231115A / AT2023xvj: Updated GIT analysis
  99. GRB 231115A: archival Chandra X-ray observations
  100. GRB 231115A: Upper limits from a neutrino search with IceCube

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