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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 S190828j: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  2. LIGO/Virgo S190828j: No counterpart candidates in HAWC observations
  3. LIGO/Virgo S190828j: No counterpart candidates in AGILE-MCAL observations
  4. LIGO/Virgo S190828j: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo S190814bv: Correction of ASKAP coordinates
  6. LIGO/Virgo S190814bv: DESGW non-detection of AT2019osy/ASKAP 005547-270433
  7. LIGO/Virgo S190814bv: Palomar 200-in spectroscopic redshift and host galaxy properties of ASKAP source AT2019osy
  8. Fermi trigger No 588597173 Global MASTER-Net observations report
  9. LIGO/Virgo S190814bv: Optical non-detection of radio source AT2019osy from CFHT
  10. Fermi GBM-190816: Eight additional candidates from the Zwicky Transient Facility
  11. GRB 190827A: BALROG localization (Fermi Trigger 588597173 / GRB 190827467)
  12. GRB 190827A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo S190814bv: DECam-GROWTH detection of an optical counterpart to the radio source AT2019osy
  14. LIGO/Virgo S190814bv: Detection of a candidate radio counterpart with ASKAP
  15. LIGO/Virgo S190814bv: Final list of candidates from the DESGW coadd analysis from the week long search campaign
  16. LIGO/Virgo S190814bv: CFHTphotometryof AT2019npv
  17. LIGO/Virgo S190814bv: SOAR spectroscopy of DECam candidates AT2019npw and AT2019num
  18. LIGO/Virgo S190814bv : Magellan IMACS Spectrum of AT2019npv classified as a Type Ib supernova
  19. GRB 190824A, Swift-BAT refined analysis
  20. LIGO/Virgo S190814bv: SALT optical spectrum of candidate DG19aqbkc
  21. LIGO/Virgo S190814bv: Radio non-detection of DG19wxnjc/AT2019npv with the VLA
  22. GRB 190824A: Swift/UVOT Upper Limits
  23. LIGO/Virgo S190814bv: Keck II NIRES classification of DG19wxnjc/AT2019npv as a stripped envelope supernova
  24. LIGO/Virgo S190814bv: LCO Photometry of DG19wxnjc/AT2019npv
  25. GRB 190823A: Swift-XRT observations
  26. Fermi trigger No 588398821 Global MASTER-Net observations report
  27. LIGO/Virgo S190814bv: MASTER prediscovery and postdiscovery observations DECam candidate DG19wxnjc/AT2019npv field
  28. GRB 190816A: Swift-XRT afterglow detection
  29. LIGO/Virgo S190814bv: No radio counterpart to DG19wxnjc/AT2019npv in ASKAP observations
  30. GRB 190825A: Fermi GBM Final Real-time Localization
  31. GRB 190824A: Swift-XRT refined Analysis
  32. GRB 190824A: Fermi GBM observation
  33. LIGO/Virgo S190814bv: Archival detection of DG19wxnjc/AT2019npv in DES data
  34. Fermi trigger No 588350802 Global MASTER-Net observations report
  35. GRB 190824A: Enhanced Swift-XRT position
  36. Fermi GBM-190816: Updated localization of subthreshold GRB-GW candidate
  37. GRB 190821A: Swift-BAT refined analysis
  38. GRB 190824A: Swift detection of a burst
  39. GRB 190824A: Fermi GBM Final Real-time Localization
  40. LIGO/Virgo S190814bv: Keck NIRES spectroscopy of DG19wxnjc/AT2019npv
  41. LIGO/Virgo S190814bv: Photometric Evolution of DECAM candidates
  42. GRB 190823A: Tiled Swift observations
  43. LIGO/Virgo S190814bv: DESGW photometry of AT2019npv
  44. LIGO/Virgo S190814bv: GROND follow-up observations of AT2019npv
  45. GRB 190823A: MAXI/GSC detection
  46. LIGO/Virgo S190814bv: Further Pan-STARRS z-band observations and AT2019npv photometry
  47. LIGO/Virgo S190814bv: WHT spectroscopy of the host of AT2019npv
  48. Fermi trigger No 588185734 Global MASTER-Net observations report
  49. Fermi GBM-190816: Coverage and upper limits from MAXI/GSC observations
  50. Fermi trigger No 588115134 Global MASTER-Net observations report
  51. GRB 190821A: Swift/UVOT Upper Limits
  52. LIGO/Virgo S190814bv: NIR imaging follow-up of ASKAP transient
  53. GRB 190821A: MASTER VWFC syncronous optical observations
  54. LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate
  55. Fermi GBM-190816: MASTER-Net optical observation report
  56. LIGO/Virgo S190814bv: No radio counterpart detected in ASKAP observations
  57. GRB 190821A: Swift-XRT refined Analysis
  58. LIGO/Virgo S190814bv: a potential faint optical counterpart in CFHT imaging
  59. LIGO/Virgo S190822c: Retraction of GW compact binary merger candidate
  60. LIGO/Virgo S190822c: CLU/NED Galaxies in the 50% Localization Volume
  61. LIGO/Virgo S190822c Global MASTER-Net observations report
  62. LIGO/Virgo S190822c: Upper limits from IceCube neutrino searches
  63. LIGO/Virgo S190814bv: new candidate from DESGW
  64. LIGO/Virgo S190814bv: No Optical Counterpart Candidates in Second-Epoch Lick/KAIT Observations
  65. GRB 190821A: Enhanced Swift-XRT position
  66. GRB 190821A: Fermi GBM observation
  67. Fermi GBM-190816: Upper Limits from Swift/BAT Observations
  68. GRB 190821A: MASTER do not see any afterglow candidate
  69. Fermi GBM-190816: Correction from the Zwicky Transient Facility
  70. GRB 190821A: T60 Les Makes optical detection of the afterglow
  71. Fermi GBM-190816: Four additional candidates from the Zwicky Transient Facility
  72. Swift GRB190821.72 Global MASTER-Net observations report
  73. Fermi trigger No 588100239 Global MASTER-Net observations report
  74. GRB 190821A: Swift detection of a burst
  75. Fermi GBM-190816: No counterpart candidates in Fermi-LAT observations
  76. LIGO/Virgo S190814bv: further candidates from DESGW
  77. Fermi GBM-190816: AGILE in SAA at T0
  78. LIGO/Virgo S190814bv: SOAR spectroscopy of AT2019noq and AT2019ntn
  79. LIGO/Virgo S190814bv: No Counterpart Candidates in Las Cumbres Observatory Galaxy Targeted Search
  80. Fermi GBM-190816: ZTF19abqanpy 10.4m GTC spectroscopy
  81. Fermi-LAT Gamma-ray Observations of IceCube-190819A
  82. LIGO/Virgo S190814bv: AT2019nqq 10.4m GTC spectroscopy
  83. Fermi GBM-190816: One candidate counterpart from the Zwicky Transient Facility
  84. LIGO/Virgo S190814bv: Further Pan-STARRS observations and transient sources
  85. LIGO/Virgo S190814bv: RATIR Optical observations of DECam transients
  86. LIGO/Virgo GBM-190816: no counterpart candidates in the Swift/BAT Observations
  87. Fermi GBM-190816: Upper limits from IceCube neutrino searches
  88. IceCube-190819A: Upper limits from a search for additional neutrino events in IceCube
  89. IceCube-190819A: MASTER analysis
  90. IceCube-190819A - HAWC follow-up
  91. Fermi GBM-190816: No counterpart candidates in HAWC observations
  92. LIGO/Virgo S190814bv: No neutrino candidates at Pierre Auger Observatory
  93. Fermi GBM-190816+LIGO/Virgo : no neutrino counterpart candidate in ANTARES search
  94. Fermi GBM-190816: Location-dependent upper limits from INTEGRAL/SPI-ACS prompt observation
  95. Fermi GBM-190816: A subthreshold GRB candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  96. GRB 190816A: Swift-BAT refined analysis
  97. IceCube-190819A: Upper limits from Fermi-GBM Observations
  98. IceCube-190819A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  99. IceCube-190819A - IceCube observation of a high-energy neutrino candidate event
  100. LIGO/Virgo S190814bv: GRAWITA TNG NIR imaging of AT2019nqq and AT2019nqc

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