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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"

28058 results found.

  1. GRB 200303A: Swift-XRT refined Analysis
  2. GRB 200303A: Swift-BAT refined analysis
  3. LIGO/Virgo S200302c: Upper limits from Insight-HXMT/HE observations
  4. GRB 200303A: Swift/UVOT Upper Limits
  5. GRB 200303A: GOTO observations upper limit
  6. GRB 200303A: Optical limit from CAHA
  7. GRB 200303A: Enhanced Swift-XRT position
  8. GRB 200303A: Swift detection of a burst
  9. LIGO/Virgo S200302c: Updated Sky Localization
  10. LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
  11. LIGO/Virgo S200302c: no counterpart candidates in the Swift/BAT observations
  12. LIGO/Virgo S200224ca: Transient found in Swift/UVOT counterpart search
  13. LIGO/Virgo S200302c: No counterpart candidates in HAWC observations
  14. LIGO/Virgo S200302c: Upper limits from Fermi-GBM Observations
  15. LIGO/Virgo S200302c: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  16. LIGO/Virgo S200302c : no neutrino counterpart candidate in ANTARES search
  17. LIGO/Virgo S200302c: upper limits from AGILE/MCAL observations
  18. LIGO/Virgo S200225q: AstroSat CZTI upper limits
  19. LIGO/Virgo S200219ac: AstroSat CZTI upper limits
  20. LIGO/Virgo S200302c: Coverage and upper limits from MAXI/GSC observations
  21. LIGO/Virgo S200302c: Upper limits from IceCube neutrino searches
  22. LIGO/Virgo S200302c: Identification of a GW compact binary merger candidate
  23. GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
  24. LIGO/Virgo S200225q : No significant candidates in TAROT - FRAM - GRANDMA observations.
  25. GRB 200228B: LCO Optical Upper Limit
  26. GRB 200228B: Swift-BAT refined analysis
  27. GRB 200228B: RATIR Optical Observations
  28. GRB 200228B: Liverpool Telescope imaging
  29. GRB 200228B: Swift-XRT refined Analysis
  30. GRB 200228B: Swift/UVOT Upper Limits
  31. GRB 200228B: RATIR Optical Observations
  32. GRB 200228B: Fermi GBM observation
  33. GRB 200227A: RATIR Optical Observations
  34. IceCube-200227A: Upper limits from a search for additional neutrino events in IceCube
  35. LIGO/Virgo S200224ca: Updated Sky Localization and EM Bright Classification
  36. GRB 200228C: Insight-HXMT/HE detection
  37. GRB 200228A: Fermi GBM observation
  38. GRB 200227A: Mondy optical upper limit
  39. GRB 200228B: Enhanced Swift-XRT position
  40. Fermi-LAT Gamma-ray Observations of IceCube-200227A
  41. GRB 200228B: Swift detection of a burst
  42. GRB 200227A: Insight-HXMT/HE detection
  43. IceCube-200227A : Upper limits from Insight-HXMT/HE observations
  44. GRB 200227A: Swift-XRT refined Analysis
  45. GRB 200228A: BALROG localization (Fermi Trigger 604565918 / GRB 200228291)
  46. GRB 200227A: Swift-BAT refined analysis
  47. GRB 200227A: Swift/UVOT Upper Limits
  48. GRB 200227A: Enhanced Swift-XRT position
  49. HAWC-200216A: No Neutrino Counterpart in ANTARES Search
  50. GRB 200224A: Mondy optical upper limit
  51. GRB 200227A: Fermi GBM observation
  52. LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
  53. IceCube-200227A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  54. GRB 200227A: Swift detection of a burst
  55. LIGO/Virgo S200224ca: Upper limits from CALET observations.
  56. LIGO/Virgo S200224car: GRAWITA VST-ESO PARANAL observations.
  57. LIGO/Virgo S200225q: Updated Sky Localization
  58. LIGO/Virgo S200219ac: Upper limits from Konus-Wind observations
  59. LIGO/Virgo S200213t: Upper limits from Konus-Wind observations
  60. LIGO/Virgo S200208q: Upper limits from Konus-Wind observations
  61. GRB 200224A: Calar Alto 2.2m optical afterglow detection
  62. LIGO/Virgo S200225q: no counterpart candidate in SVOM/GWAC observations
  63. LIGO/Virgo S200225q: Upper limits from Insight-HXMT/HE observations
  64. LIGO/Virgo S200224ca: Upper limits from Insight-HXMT/HE observations
  65. LIGO/Virgo S200225q: no counterpart candidates in the Swift/BAT observations
  66. LIGO/Virgo S200224ca: no counterpart candidates in the Swift/BAT observations
  67. GRB 200224B: DDOTI/OAN optical observations report
  68. LIGO/Virgo S200219ac: Updated Sky Localization
  69. LIGO/Virgo S200224ca: No Counterparts in DDOTI/OAN Optical Observations
  70. LIGO/Virgo S200224ca: GRAWITA-Campo Imperatore observations.
  71. LIGO/Virgo S200225q: Upper limits from Fermi-GBM Observations
  72. LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
  73. LIGO/Virgo S200225q: upper limits from AGILE/GRID observations
  74. LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
  75. LIGO/Virgo S200225q: upper limits from AGILE/MCAL observations
  76. LIGO/Virgo S200225q: Upper limits from IceCube neutrino searches
  77. LIGO/Virgo S200225q: No counterpart candidates in HAWC observations
  78. LIGO/Virgo S200225q : no neutrino counterpart candidate in ANTARES search
  79. LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
  80. LIGO/Virgo S200225q: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  81. LIGO/Virgo S200225q: Coverage and upper limits from MAXI/GSC observations
  82. LIGO/Virgo S200219ac: No counterpart candidates from Nanshan/NEXT observations
  83. LIGO/Virgo S200224ca: upper limits from AGILE/GRID observations
  84. GRB 200224A: Swift-BAT refined analysis
  85. LIGO/Virgo S200225q: Identification of a GW compact binary merger candidate The LIGO Scientific Collaboration and the Virgo Collaboration
  86. GRB 200224A: LCO Upper Limits
  87. LIGO/Virgo S200224ca: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  88. GRB 200224A: RATIR Optical Observations and Confirmation of the Afterglow
  89. LIGO/Virgo S200224ca: Coverage and upper limits from MAXI/GSC observations
  90. LIGO/Virgo S200224ca: upper limits from AGILE/MCAL observations
  91. LIGO/Virgo S200224ca: Upper limits from IceCube neutrino searches
  92. LIGO/Virgo S200224ca: Identification of a GW compact binary merger candidate The LIGO Scientific Collaboration and the Virgo Collaboration
  93. GRB 200224A: Swift/UVOT Detection
  94. GRB 200224A: Swift-XRT refined Analysis
  95. GRB 200224A: Tautenburg observations
  96. GRB 200224A: BOOTES-1 and 1.5m OSN optical observations
  97. GRB 200224A: Swift detection of a burst
  98. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC-F30 observations
  99. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC observations
  100. LIGO/Virgo S200219ac : No significant candidates in TAROT - FRAM - GRANDMA observations.

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