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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 S190828l: no counterpart candidates in the Swift/BAT Observations
  2. LIGO/Virgo S190828j: no counterpart candidates in the Swift/BAT Observations
  3. LIGO/Virgo S190828j: No counterpart candidates in KAIT observations
  4. LIGO/Virgo S190828j: No counterpart candidates in Fermi-LAT observations
  5. GRB 190828A: Tiled Swift observations
  6. GRB 190828D: A long GRB detected by INTEGRAL
  7. Integral GRB190828.78 Global MASTER-Net observations report
  8. LIGO/Virgo S190814bv: no variation of DESGW candidates AT 2019onj and AT 2019okr from ENGRAVE VLT/HAWK-I observations, and archival detection
  9. LIGO/Virgo S190814bv: Swift UVOT - no new counterpart candidates identified
  10. GRB 190828B: Dabancheng-0.5m optical upper limit
  11. LIGO/Virgo S190828l: Upper limits from Fermi-GBM Observations
  12. LIGO/Virgo S190828j: Upper limits from Fermi-GBM Observations
  13. GRB 190828B: Enhanced Swift-XRT position
  14. GRB 190828C: BALROG localization (Fermi Trigger 588696271 / GRB 190828614)
  15. GRB 190828C: Fermi GBM Final Real-time Localization
  16. Swift GRB190828.54 Global MASTER-Net observations report
  17. GRB 190828B: Swift detection of a burst
  18. GRB 190828B: Fermi GBM Final Real-time Localization
  19. LIGO/Virgo S190828l: Upper limits from AGILE-GRID observations
  20. LIGO/Virgo S190828l: Upper limits from IceCube neutrino searches
  21. LIGO/Virgo S190828j: Upper limits from IceCube neutrino searches
  22. LIGO/Virgo S190828l Global MASTER-Net observations report
  23. LIGO/Virgo S190828l: Coverage and upper limits from MAXI/GSC observations
  24. LIGO/Virgo S190828l: No counterpart candidates in AGILE-MCAL observations
  25. LIGO/Virgo S190828j: Coverage and upper limits from MAXI/GSC observations
  26. LIGO/Virgo S190828j : no neutrino counterpart candidate in ANTARES search
  27. LIGO/Virgo S190828l : no neutrino counterpart candidate in ANTARES search
  28. LIGO/Virgo S190828j: Upper limits from AGILE-GRID observations
  29. LIGO/Virgo S190828l: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  30. LIGO/Virgo S190828j: Updated Sky Localization
  31. LIGO/Virgo S190828l: Identification of a GW compact binary merger candidate
  32. GRB 190828A: MAXI/GSC detection
  33. LIGO/Virgo S190828l: No counterpart candidates in HAWC observations
  34. LIGO/Virgo S190828j: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  35. LIGO/Virgo S190828j: No counterpart candidates in HAWC observations
  36. LIGO/Virgo S190828j: No counterpart candidates in AGILE-MCAL observations
  37. LIGO/Virgo S190828j: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo S190814bv: Correction of ASKAP coordinates
  39. LIGO/Virgo S190814bv: DESGW non-detection of AT2019osy/ASKAP 005547-270433
  40. LIGO/Virgo S190814bv: Palomar 200-in spectroscopic redshift and host galaxy properties of ASKAP source AT2019osy
  41. Fermi trigger No 588597173 Global MASTER-Net observations report
  42. LIGO/Virgo S190814bv: Optical non-detection of radio source AT2019osy from CFHT
  43. Fermi GBM-190816: Eight additional candidates from the Zwicky Transient Facility
  44. GRB 190827A: BALROG localization (Fermi Trigger 588597173 / GRB 190827467)
  45. GRB 190827A: Fermi GBM Final Real-time Localization
  46. LIGO/Virgo S190814bv: DECam-GROWTH detection of an optical counterpart to the radio source AT2019osy
  47. LIGO/Virgo S190814bv: Detection of a candidate radio counterpart with ASKAP
  48. LIGO/Virgo S190814bv: Final list of candidates from the DESGW coadd analysis from the week long search campaign
  49. LIGO/Virgo S190814bv: CFHTphotometryof AT2019npv
  50. LIGO/Virgo S190814bv: SOAR spectroscopy of DECam candidates AT2019npw and AT2019num
  51. LIGO/Virgo S190814bv : Magellan IMACS Spectrum of AT2019npv classified as a Type Ib supernova
  52. GRB 190824A, Swift-BAT refined analysis
  53. LIGO/Virgo S190814bv: SALT optical spectrum of candidate DG19aqbkc
  54. LIGO/Virgo S190814bv: Radio non-detection of DG19wxnjc/AT2019npv with the VLA
  55. GRB 190824A: Swift/UVOT Upper Limits
  56. LIGO/Virgo S190814bv: Keck II NIRES classification of DG19wxnjc/AT2019npv as a stripped envelope supernova
  57. LIGO/Virgo S190814bv: LCO Photometry of DG19wxnjc/AT2019npv
  58. GRB 190823A: Swift-XRT observations
  59. Fermi trigger No 588398821 Global MASTER-Net observations report
  60. LIGO/Virgo S190814bv: MASTER prediscovery and postdiscovery observations DECam candidate DG19wxnjc/AT2019npv field
  61. GRB 190816A: Swift-XRT afterglow detection
  62. LIGO/Virgo S190814bv: No radio counterpart to DG19wxnjc/AT2019npv in ASKAP observations
  63. GRB 190825A: Fermi GBM Final Real-time Localization
  64. GRB 190824A: Swift-XRT refined Analysis
  65. GRB 190824A: Fermi GBM observation
  66. LIGO/Virgo S190814bv: Archival detection of DG19wxnjc/AT2019npv in DES data
  67. Fermi trigger No 588350802 Global MASTER-Net observations report
  68. GRB 190824A: Enhanced Swift-XRT position
  69. Fermi GBM-190816: Updated localization of subthreshold GRB-GW candidate
  70. GRB 190821A: Swift-BAT refined analysis
  71. GRB 190824A: Swift detection of a burst
  72. GRB 190824A: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo S190814bv: Keck NIRES spectroscopy of DG19wxnjc/AT2019npv
  74. LIGO/Virgo S190814bv: Photometric Evolution of DECAM candidates
  75. GRB 190823A: Tiled Swift observations
  76. LIGO/Virgo S190814bv: DESGW photometry of AT2019npv
  77. LIGO/Virgo S190814bv: GROND follow-up observations of AT2019npv
  78. GRB 190823A: MAXI/GSC detection
  79. LIGO/Virgo S190814bv: Further Pan-STARRS z-band observations and AT2019npv photometry
  80. LIGO/Virgo S190814bv: WHT spectroscopy of the host of AT2019npv
  81. Fermi trigger No 588185734 Global MASTER-Net observations report
  82. Fermi GBM-190816: Coverage and upper limits from MAXI/GSC observations
  83. Fermi trigger No 588115134 Global MASTER-Net observations report
  84. GRB 190821A: Swift/UVOT Upper Limits
  85. LIGO/Virgo S190814bv: NIR imaging follow-up of ASKAP transient
  86. GRB 190821A: MASTER VWFC syncronous optical observations
  87. LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate
  88. Fermi GBM-190816: MASTER-Net optical observation report
  89. LIGO/Virgo S190814bv: No radio counterpart detected in ASKAP observations
  90. GRB 190821A: Swift-XRT refined Analysis
  91. LIGO/Virgo S190814bv: a potential faint optical counterpart in CFHT imaging
  92. LIGO/Virgo S190822c: Retraction of GW compact binary merger candidate
  93. LIGO/Virgo S190822c: CLU/NED Galaxies in the 50% Localization Volume
  94. LIGO/Virgo S190822c Global MASTER-Net observations report
  95. LIGO/Virgo S190822c: Upper limits from IceCube neutrino searches
  96. LIGO/Virgo S190814bv: new candidate from DESGW
  97. LIGO/Virgo S190814bv: No Optical Counterpart Candidates in Second-Epoch Lick/KAIT Observations
  98. GRB 190821A: Enhanced Swift-XRT position
  99. GRB 190821A: Fermi GBM observation
  100. Fermi GBM-190816: Upper Limits from Swift/BAT Observations

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