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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 G194575: CQUEAN/LOAO observations
  2. GRB 151023A: Enhanced Swift-XRT position
  3. Possible Fermi-LAT Gamma-ray counterpart for LIGO/Virgo G194575
  4. LIGO/Virgo G194575: LOFAR follow-up
  5. GRB 151022A: Swift/UVOT Upper Limits
  6. LIGO/Virgo G194575: RATIR Observations of Nearby Galaxies in the 1sigma Error Region
  7. LIGO Virgo G194575: MWA Observations
  8. LIGO/Virgo G194575: INTEGRAL search of temporally coincident prompt hard X-ray emission
  9. LIGO/Virgo G194575: RATIR Observations of Nearby Galaxies in the 1sigma Error Region
  10. GRB 151022A: Swift-BAT refined analysis
  11. LIGO/Virgo G194575: more details on transients from Pan-STARRS in the RA=1hr localisation region
  12. GRB 151023A: Swift detection of a burst
  13. GRB 151022A: RATIR Upper Limits
  14. GRB 151022A: Swift-XRT refined Analysis
  15. LIGO/Virgo G194575: Fermi GBM Observations
  16. GRB 151022A: MITSuME Okayama upper limits
  17. LIGO/Virgo G194575: Mini-MegaTORTORA observations
  18. LIGO/Virgo G194575: transients from Pan-STARRS in the RA=1hr localisation region
  19. GRB 151022A: Enhanced Swift-XRT position
  20. LIGO Virgo G194575: TZAC TAROT observations
  21. LIGO/Virgo G194575: Identification of a GW CBC Candidate
  22. GRB 151022A: Mondy optical upper limit
  23. GRB 151022A: MITSuME Okayama Ks-band upper-limit
  24. GRB 151022A: Kanata/HOWPol optical observation
  25. GRB 151022A: Prompt enhanced Swift-XRT position
  26. GRB 151022A: MASTER-Ural observations
  27. GRB 151022A: Swift detection of a burst
  28. GRB 151021A: MITSuME Okayama Ks-band upper-limit
  29. GRB 151021B: Fermi GBM detection
  30. Konus-Wind observation of GRB 151021A
  31. GRB 151021A: Swift/UVOT Detection
  32. GRB 151021A: MITSuME Okayama upper limits
  33. GRB 151021A: Swift-XRT refined Analysis
  34. GRB 151021A: Swift-BAT refined analysis
  35. GRB 151021A: Enhanced Swift-XRT position
  36. GRB 151021A: MASTER-NET bright OT detection
  37. GRB 151021A: Optical counterpart and redshift from X-shooter
  38. GRB 151021A: Swift detection of a burst
  39. LIGO/Virgo G184098: LOFAR follow-up
  40. GRB 151004A: Swift-XRT follow-up observations
  41. GRB 151006A: Astrosat CZTI detection
  42. Trigger 659734: Swift detection of SAX J1750.8-2900 or other source near Galactic center
  43. LIGO/Virgo G184098: VLA follow-up of iPTF15cyk
  44. Fermi GBM trigger 466602792/151015495 is not a GRB
  45. LIGO/VIRGO G184098 : PESSTO classifications of PanSTARRS transients in the northern region
  46. Fermi GBM trigger 466316973/151012187 is not a GRB
  47. GRB 151006A: Mondy optical upper limit
  48. GRB 151006A: MITSuME Akeno optical upper limits
  49. Fermi GBM trigger 466059859/151009211 is not a GRB
  50. Konus-Wind observation of GRB 151006A
  51. Swift Trigger 658045 is not a GRB
  52. GRB 151006A: OSN optical upper limit
  53. GRB 151006A: Swift-BAT refined analysis
  54. GRB 151006A: MITSuME Okayama Ks-band upper-limit
  55. GRB 151006A: Swift-XRT refined Analysis
  56. GRB 151006A: Fermi-LAT detection
  57. GRB 151006A: Swift/UVOT Upper Limits
  58. GRB 151006A: Fermi GBM detection
  59. GRB 151006A: Enhanced Swift-XRT position
  60. GRB 151006A: MITSuME Okayama upper limits
  61. Konus-Wind observation of GRB 151001B
  62. GRB 151006A: Kanata/HOWPol optical imaging polarimetry
  63. GRB 151006A: Prompt enhanced Swift-XRT position
  64. GRB 151006A: Swift detection of a burst
  65. LIGO/Virgo G184098: Further VST-ESO PARANAL observations
  66. Trigger 657564 / GRB 151004A: Swift BAT and XRT refined analysis
  67. LIGO/VIRGO G184098 : PESSTO classification of PS15cbm in the northern region
  68. LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients
  69. Trigger 657564 / GRB 151004A: Swift/UVOT Upper Limits
  70. Swift Trigger 657564: MASTER-NET early optical observations.
  71. Swift Trigger 657564: XRT prompt analysis
  72. LIGO/Virgo G184098: MASTER OTs detection and Scenario Machine prediction
  73. Swift Trigger 657564: a probable GRB
  74. LIGO/Virgo G184098: Ongoing gravitational-wave analysis
  75. GRB 151001A: Swift-BAT refined analysis
  76. GRB 151001A: RATIR Observations
  77. GRB 151001B: Swift/UVOT Upper Limits
  78. GRB 151001B: Swift-XRT refined Analysis
  79. GRB 151001B: Swift-BAT refined analysis
  80. GRB 151001A: Swift/UVOT Detection
  81. GRB 151001B: MASTER-NET early optical observations.
  82. GRB 151001A: NOT imaging
  83. GRB 151001A: Swift-XRT refined Analysis
  84. GRB 151001B: Enhanced Swift-XRT position
  85. GRB 151001A: Enhanced Swift-XRT position
  86. GRB 151001A: Fermi GBM detection
  87. GRB 151001B: Swift detection of a burst
  88. GRB 151001A: Swift detection of a burst with an optical counterpart
  89. LIGO/Virgo G184098: spectral classification of PS15cci
  90. LIGO/Virgo G184098: Update to LT Spectroscopy of PS15ccx
  91. LIGO/Virgo G184098: Liverpool Telescope Spectroscopy of PS15ccx
  92. GRB 150925A: Swift/UVOT Upper Limits
  93. GRB 150925A: Swift-BAT refined analysis
  94. GRB 150925A: Swift-XRT refined Analysis
  95. GRB 150925A: Enhanced Swift-XRT position
  96. GRB 150925A: Swift detection of a burst
  97. LIGO/Virgo G184098: LOFAR follow-up
  98. LIGO/Virgo G184098: ASKAP followup
  99. LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients
  100. LIGO/Virgo G184098: optical transient search with Kiso Schmidt telescope and KWFC on behalf of J-GEM collaboration

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