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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. LIGO/Virgo S190808ae: Coverage and upper limits from MAXI/GSC observations
  2. LIGO/Virgo S190808ae: CLU/NED Galaxies in the 50% Localization Volume
  3. LIGO/Virgo S190808ae: No counterpart candidates in HAWC observations
  4. LIGO/Virgo S190808ae: One Coincident Neutrino Candidate from IceCube Search
  5. LIGO/Virgo S190808ae: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo S190808ae Global MASTER-Net observations report
  7. GRB 190808B: BALROG localization (Fermi Trigger 586980202 / GRB 190808752)
  8. Fermi trigger No 586980202 Global MASTER-Net observations report
  9. GRB 190808B: Fermi GBM Final Real-time Localization
  10. HAWC Burst Alert 1008846_957: IceCube Neutrino Search
  11. GRB 190808A: Fermi GBM Final Real-time Localization
  12. GRB 190804A: AstroSat CZTI detection
  13. Fermi trigger No 586896678 Global MASTER-Net observations report
  14. GRB 190805B: AstroSat CZTI detection
  15. GRB 190804B: Swift-XRT afterglow detection
  16. Konus-Wind observation of GRB 190805B
  17. Alert from the HAWC Burst Monitor
  18. HAWC Alert 190806.56 Global MASTER-Net observations report
  19. Fermi trigger No 586788607 Global MASTER-Net observations report
  20. Fermi trigger No 586800758 Global MASTER-Net observations report
  21. GRB 190806A: Fermi GBM Final Real-time Localization
  22. GRB 190805B: Swift-XRT observations
  23. Fermi trigger No 586676451 Global MASTER-Net observations report
  24. GRB 190805B: Fermi GBM detection
  25. LIGO/Virgo S190728q: AT2019lvw 10.4m GTC spectroscopy
  26. GRB 190805B: Tiled Swift observations
  27. Konus-Wind observation of GRB 190731A
  28. GRB 190804B: Swift-XRT observations
  29. GRB 190805B: BALROG localization (Fermi Trigger 586673165 / GRB 190805199)
  30. GRB 190805B: MAXI/GSC detection
  31. GRB 190805B: Fermi GBM Final Real-time Localization
  32. GRB 190805A: Fermi GBM Final Real-time Localization
  33. Fermi trigger No 586638042 Global MASTER-Net observations report
  34. MAXI GRB190804.33 Global MASTER-Net observations report
  35. Fermi trigger No 586600841 Global MASTER-Net observations report
  36. GRB 190804C: BALROG localization (Fermi Trigger 586638042 / GRB 190804792)
  37. GRB 190804C: Fermi GBM Final Real-time Localization
  38. GRB 190804B: Tiled Swift observations
  39. GRB 190804B: MAXI/GSC detection
  40. LIGO/Virgo S190728q: AT2019lzc 10.4m GTC spectroscopy
  41. Fermi trigger No 586574612 Global MASTER-Net observations report
  42. GRB 190804A: Fermi GBM Final Real-time Localization
  43. GRB 190731A: AstroSat CZTI detection
  44. GRB 190731A: Swift/UVOT Upper Limits
  45. GRB 190731A: no OT detected by MASTER
  46. IceCube 190730A: No counterpart candidates or blazar activity in GOTO observations
  47. GRB 190720B: AstroSat CZTI detection
  48. LIGO/Virgo S190728q: AT2019lzt 10.4m GTC spectroscopy
  49. GRB 190719C: VLT/X-shooter spectroscopic redshift of the host galaxy
  50. GRB 190731A: Swift-XRT afterglow detection
  51. IPN Triangulation of GRB 190731A
  52. LIGO/Virgo S190727h: Updated sky localization
  53. GRB 190731A: Fermi GBM detection
  54. GRB 190726B: AstroSat CZTI detection
  55. GRB 190731A: CALET Gamma-Ray Burst Monitor detection
  56. GRB 190731A: Swift ToO observations
  57. GRB190731A: Fermi-LAT detection
  58. Fermi trigger No 586305505 Global MASTER-Net observations report
  59. Fermi trigger No 586305505 Global MASTER-Net observations report
  60. IceCube-190730A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 190731A: Fermi GBM Final Real-time Localization
  62. Fermi-LAT Gamma-ray Observations of IceCube-190730A
  63. IceCube-190730A - HAWC follow-up
  64. LIGO/Virgo S190728q: No counterpart candidates in H.E.S.S. observations
  65. LIGO/Virgo S190728q: Correction to GCN #25235: also PS19dxm and DG19zrjmb are not associated with S190728q
  66. LIGO/Virgo S190728q: ZTF Forced Photometry for PS1 and DECam-GROWTH optical candidates, and a note on DECam Photometry from GCN 25215
  67. Fermi trigger No 586240252 Global MASTER-Net observations report
  68. IceCube 190730A: not observable by Fermi-GBM
  69. IceCube 190730A: one weakly associated counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
  70. IceCube-190730A: MASTER optical observation
  71. LIGO/Virgo S190707q: AstroSat CZTI upper limits
  72. LIGO/Virgo S190718y: AstroSat CZTI upper limits
  73. LIGO/Virgo S190727h: AstroSat CZTI upper limits
  74. LIGO/Virgo S190720a: AstroSat CZTI upper limits
  75. LIGO/Virgo S190728q: MITSuME Okayama and Bisei Follow-Up of ZTF19abjethn (AT2019lvs)
  76. IceCube-190730A - IceCube observation of a high-energy neutrino candidate event
  77. LIGO/Virgo S190728q: Optical transients from Pan-STARRS coverage during first 2 nights
  78. LIGO/Virgo S190727h: Gaia Photometric Alerts transient candidate
  79. LIGO/Virgo S190728q: GRAWITA VST-ESO PARANAL observations
  80. LIGO/Virgo s190728q: ePESSTO+ NTT classification of AT2019lvt as a type-Ia SN
  81. LIGO/Virgo S190728q/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  82. Fermi Gamma-ray Burst Monitor trigger 190729668/586108936 is not a GRB
  83. Konus-Wind observation of GRB 190727B
  84. LIGO/VIRGO S190728q: No candidate counterparts from ATLAS observations
  85. S190728q: MASTER multiple previous outbursts detection of ZTF19abjethn=AT2019lvs
  86. LIGO/Virgo S190728q: Optical Counterpart Candidates from DECam-GROWTH
  87. LIGO/Virgo S190728q: No transient candidates in CALET observations
  88. LIGO/Virgo S190728q: No counterpart candidates in KAIT observations
  89. LIGO/Virgo S190728q: ZTF19abjethn TShAO and NUTTelA-TAO optical observations / classification
  90. GRB 190727B: Swift-BAT refined analysis
  91. LIGO/Virgo S190728q: Third update on neutrino search with IceCube
  92. LIGO/Virgo S190728q: Classification of AT2019lvs/ZTF19abjethn as a CV
  93. LIGO/Virgo S190728q: Update on Sky-Localization and Source-Classification
  94. LIGO/Virgo S190728q: ZTF19abjethn is inconsistent with new GW localization
  95. LIGO/Virgo S190728q: LCO Follow-Up of ZTF19abjethn (AT2019lvs)
  96. IPN triangulation of GRB 190728A (short)
  97. LIGO/Virgo S190728q: Pan-STARRS detection of the transient AT2019lvs/ZTF19abjethn 18hrs before S190728q
  98. LIGO/Virgo S190728q: declination for GCN 25202
  99. LIGO/Virgo S190728q: Identification of a Faint Blue Static Source at the Location of ZTF19abjethn
  100. LIGO/Virgo S190728q: Photometric Redshift and Stellar Mass Estimates for the Potential Host Galaxy of Optical Counterpart Candidate ZTF19abjethn

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