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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"

19548 results found.

  1. GRB 190613B: Enhanced Swift-XRT position
  2. IPN Triangulation of GRB 190611B
  3. GRB 190613A: Enhanced Swift-XRT position
  4. GRB 190613B: Swift detection of a burst with an optical counterpart
  5. GRB 190613A: Swift detection of a burst with an optical counterpart
  6. GRB 190611A: Swift/UVOT Upper Limits
  7. GRB 190611A: Optical observations from VLT/FORS2
  8. GRB 190611A: Enhanced Swift-XRT position
  9. GRB 190611A: Swift detection of a burst
  10. GRB 190608A: Fermi GBM Final Real-time Localization
  11. LIGO/Virgo S190425z: Swift UVOT - no new sources identified, and a summary of the Swift UVOT processing of GW triggers.
  12. GRB 190604B: VLT Afterglow Detection
  13. GRB 190604B: Kitab observatory optical upper limit
  14. GRB190604B: GROWTH-India telescope followup - no optical counterpart found
  15. GRB190604B: Swift/UVOT detection
  16. GRB 190604B: Enhanced Swift-XRT position
  17. GRB190530A: Photometric follow-up with GROWTH-India telescope
  18. GRB 190604B: Swift detection of a burst
  19. LIGO/Virgo S190602aq: Upper limits from CALET observations
  20. GRB 190531B: Swift/UVOT Upper Limits
  21. GRB 190530A: R-band observation from HCT
  22. LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  23. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  24. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  25. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  26. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  27. GRB 190531B: VLT optical upper limit
  28. GRB 190530A: SAO RAS optical observations
  29. GRB 190531B: Swift-XRT afterglow detection
  30. GRB 190530A: Swift/UVOT Detection
  31. GRB 190531B: Swift ToO observations
  32. GRB 190530A: COATLI Optical Detection of the Fading Afterglow
  33. GRB 190530A: Swift-XRT afterglow detection
  34. GRB 190530A: GWAC-F30 optical detection
  35. GRB 190530A: OAJ optical detection
  36. GRB 190530A: NOT photometry and spectroscopy
  37. GRB 190530A: Swift ToO observations
  38. GRB 190530A: AGILE-MCAL detection
  39. LIGO/Virgo S190521r: CNEOST follow-up observations
  40. LIGO/Virgo S190521r: Kanata optical/NIR follow-up observations of the CNEOST Transient
  41. LIGO/Virgo S190521r: No optical counterpart from SVOM/GWAC-F30 observations.
  42. LIGO/Virgo S190521r: No optical counterpart from SVOM/GWAC observations.
  43. LIGO/Virgo S190521g: No optical counterpart from SVOM/GWAC observations.
  44. LIGO/Virgo S190521r: RATIR Optical and NIR Observations of the CNEOST Transient
  45. LIGO/Virgo S190521g: Upper limits from CALET observations
  46. LIGO/Virgo S190521g: Swift/BAT Counterpart Search
  47. LIGO/Virgo S190521r: Swift/BAT Counterpart Search
  48. LIGO/Virgo S190521g: No Counterparts in DDOTI/OAN Optical Observations
  49. LIGO/Virgo S190521r: Coverage and upper limits from Fermi-LAT observations
  50. LIGO/Virgo S190521g: No candidate counterpart in Fermi-LAT observations
  51. LIGO/Virgo S190521r: No neutrino counterpart candidates in ANTARES search
  52. LIGO/Virgo S190521r: No counterpart candidates in HAWC observations
  53. LIGO/Virgo S190521r: No counterpart candidates in INTEGRAL SPI/ACS prompt observation
  54. LIGO/Virgo S190521g: No neutrino counterpart candidates in ANTARES search
  55. LIGO/Virgo S190519bj: Fermi-LAT search for a high-energy gamma-ray counterpart
  56. LIGO/Virgo S190521g: No counterpart candidates in INTEGRAL SPI/ACS & IBIS/PICsIT prompt observations
  57. LIGO/Virgo S190521g: No counterpart candidates in HAWC observations
  58. LIGO/Virgo S190521g: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo S190521g: INTEGRAL SPI/ACS prompt observation
  60. S190519bj: No transient candidates from CALET observations
  61. LIGO/Virgo S190512at: SVOM/GWAC-F60A observations
  62. GRB 190519A: Swift/UVOT Upper Limits
  63. LIGO/Virgo S190519bj: Swift/BAT Counterpart Search
  64. GRB 190519A: Swift-BAT refined analysis
  65. LIGO/Virgo S190519bj: ANTARES neutrino search
  66. LIGO/Virgo S190519bj: HAWC follow-up
  67. LIGO/Virgo S190519bj: INTEGRAL SPI/ACS prompt observation
  68. GRB 190519A: Enhanced Swift-XRT position
  69. GRB 190519A: Swift detection of a burst
  70. LIGO/Virgo S190517h: CALET Observations
  71. LIGO/Virgo S190517h: INTEGRAL prompt observation
  72. LIGO/Virgo S190517h: Fermi-LAT search for a high-energy gamma-ray counterpart
  73. LIGO/Virgo S190517h: Swift/BAT Counterpart Search
  74. LIGO/Virgo S190517h: ANTARES neutrino search
  75. LIGO/Virgo S190517h: HAWC follow-up
  76. LIGO/Virgo S190517h: INTEGRAL/SPI-ACS prompt observation
  77. GRB 190515B: Swift/UVOT Upper Limits
  78. GRB 190515B: Optical observations from OSN
  79. GRB 190515B: Enhanced Swift-XRT position
  80. GRB 190515B: Kitab Observatory optical upper limit
  81. GRB 190515B: Swift detection of a burst
  82. LIGO/Virgo S190513bm: CALET Observations
  83. LIGO/Virgo S190513bm: Swift/BAT Counterpart Search
  84. LIGO/Virgo S190513bm: ANTARES neutrino search
  85. LIGO/Virgo S190513bm: Fermi-LAT search for a high-energy gamma-ray counterpart
  86. LIGO/Virgo S190512at: CALET Observations
  87. LIGO/Virgo S190513bm: MAXI/GSC Observations
  88. LIGO/Virgo S190513bm: INTEGRAL prompt observation
  89. LIGO/Virgo S190513bm: HAWC follow-up
  90. LIGO-Virgo S190512at: AGILE GRID observations
  91. LIGO/Virgo S190512at: Swift/BAT Counterpart Search
  92. LIGO/Virgo S190510g: Pan-STARRS and ATLAS observations and candidates
  93. LIGO/Virgo S190512at: ANTARES neutrino search
  94. LIGO/Virgo S190512at: Fermi-LAT search for a high-energy gamma-ray counterpart
  95. IPN triangulation of GRB 190510A (short)
  96. LIGO/Virgo S190510g: DOAO Observation
  97. LIGO/Virgo S190510g: CALET Observations
  98. GRB 190511A: Swift/UVOT Detection
  99. GRB 190511A: NOT optical afterglow
  100. LIGO/Virgo S190426c: VLA Follow-Up Observations of ZTF19aassfws

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