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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"

26365 results found.

  1. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  2. GRB 200405B: ATCA follow-up and ASKAP limits on pre-burst radio emission
  3. Baksan Neutrino Observatory Alert 200408.26: Global MASTER-Net observations report
  4. Fermi GBM Sub-Threshold Detection of GRB 200409A
  5. GRB 200409A: Swift-XRT refined Analysis
  6. GRB 200409A: Enhanced Swift-XRT position
  7. GRB 200409A: Swift detection of a burst with an optical counterpart
  8. GRB 200405B: LCO Optical Upper Limits
  9. GRB 200405B: Swift-XRT observations
  10. GRB 200405B: Swift/BAT-GUANO detection and *possible* arcminute localization of a short GRB
  11. GRB 200404A: BALROG localization (Fermi Trigger 607712227 / GRB 200404706)
  12. LIGO/Virgo S200316bj: Upper limits from Konus-Wind observations
  13. LIGO/Virgo S200311bg: Upper limits from Konus-Wind observations
  14. LIGO/Virgo S200302c: Upper limits from Konus-Wind observations
  15. LIGO/Virgo S200225q: Upper limits from Konus-Wind observations
  16. LIGO/Virgo S200224ca: Upper limits from Konus-Wind observations
  17. GRB 200402B: BALROG localization (Fermi Trigger 607537834 / GRB 200402688)
  18. GRB 200402A: BALROG localization (Fermi Trigger 607513182 / GRB 200402403)
  19. GRB 200325B: Optical upper limit
  20. GRB 200325B: further Swift-XRT observations
  21. GRB 200401A: Fermi GBM Final Real-time Localization
  22. GRB 200325B: Tautenburg observations
  23. IPN triangulation of GRB 200327A (short)
  24. GRB 200327A: AGILE/MCAL observations
  25. GRB 200325B: Fermi GBM observation
  26. GRB 200325B: Swift-XRT and UVOT observations
  27. GRB 200325B: LCO Optical Detection
  28. GRB 200326B: AstroSat LAXPC detection
  29. GRB 200325A: Fermi GBM observation
  30. GRB 200325B: Mondy and CrAO observations, Master MASTER OT J111012.51+274912.8 confirmation
  31. GRB 200324A: AROMA-N Optical Observation
  32. GRB 200324A, Swift-BAT refined analysis
  33. GRB 200324A:: TSHAO optical upper limit
  34. GRB 200324A: Swift/UVOT Upper Limits
  35. GRB 200325A: AGILE/MCAL observations
  36. GRB 200324A: LCO Optical Upper Limit
  37. GRB 200324A: Swift-XRT refined Analysis
  38. GRB 200324A: Konkoly Obs. optical upper limit
  39. GRB 200324A: NOT optical upper limit
  40. GRB 200324A: Tautenburg observations
  41. GRB 200324A: Enhanced Swift-XRT position
  42. GRB 200324A: Swift detection of a burst
  43. GRB 200323A: Fermi GBM detection
  44. LIGO/Virgo S200316bj: no counterpart candidate in SVOM/GWAC-F30 observations
  45. LIGO/Virgo S200316bj: Updated Sky Localization and EM Bright Classification
  46. GRB 200320B: MAXI/GSC detection
  47. GRB 200319A: BALROG localization (Fermi Trigger 606296685 / GRB 200319323)
  48. Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
  49. GW170817: Continued X-ray emission detected with Chandra at 940 days post-merger
  50. LIGO/Virgo S200316bj : No significant candidates in TAROT - FRAM - GRANDMA observations.
  51. LIGO/Virgo S200316bj: Upper limits from Insight-HXMT/HE observations
  52. Konus-Wind observation of GRB 200313B
  53. LIGO/Virgo S200316bj: no counterpart candidate in SVOM/GWAC observations
  54. LIGO/Virgo S200316bj: No neutrino candidates at Pierre Auger Observatory
  55. LIGO/Virgo S200316bj: No counterpart candidates in Fermi-LAT observations
  56. LIGO/Virgo S200316bj: No Counterparts in DDOTI/OAN Optical Observations
  57. LIGO/Virgo S200316bj: no counterpart candidates in the Swift/BAT observations
  58. LIGO/Virgo S200213t: Continued Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
  59. LIGO/Virgo S200316bj: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
  60. LIGO/Virgo S200316bj: upper limits from AGILE/GRID observations
  61. LIGO/Virgo S200316bj: upper limits from AGILE/MCAL observations
  62. LIGO/Virgo S200316bj: Upper limits from Fermi-GBM Observations
  63. LIGO/Virgo S200316bj: Coverage and upper limits from MAXI/GSC observations
  64. LIGO/Virgo S200316bj : no neutrino counterpart candidate in ANTARES search
  65. LIGO/Virgo S200316bj: Upper limits from IceCube neutrino searches
  66. LIGO/Virgo S200316bj: Identification of a GW compact binary merger candidate
  67. SGR Swift J1818.0-1607: Swift-BAT refined analysis
  68. GRB 200313A: Fermi GBM detection
  69. LIGO/Virgo S200311bg: Updated Sky Localization and EM Bright Classification
  70. GRB 200313A: BALROG localization (Fermi Trigger 605756501 / GRB 200313071)
  71. Swift GRB200312.89: Global MASTER-Net observations report
  72. Swift-BAT trigger 960986: Swift detection of a new SGR Swift J1818.0-1607
  73. LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
  74. IPN triangulation of GRB 200307A (short)
  75. LIGO/Virgo S200311bg: Coverage and upper limits from MAXI/GSC observations
  76. LIGO/Virgo S200311bg: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
  77. LIGO/Virgo S200311bg: Upper limits from IceCube neutrino searches
  78. LIGO/Virgo S200311bg: Identification of a GW compact binary merger candidate
  79. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  80. GRB 200307A: Updated localization from Fermi/GBM and Swift/BAT-GUANO
  81. GRB 200310A: MAXI/GSC detection
  82. GRB 200306C: Swift-BAT refined analysis
  83. GRB 200306C: Swift/UVOT Detection
  84. GRB 200306A: Swift/UVOT Upper Limits
  85. GRB 200306C: Calar Alto 2.2m upper limit
  86. GRB 200306A: Swift-BAT refined analysis
  87. GRB 200306C: Swift-XRT refined Analysis
  88. GRB 200306A: RATIR Optical Observations
  89. GRB 200306C: Enhanced Swift-XRT position
  90. GRB 200306C: VIRT optical upper limits
  91. GRB200306C: First Hour Liverpool Telescope Observations
  92. GRB 200306C: LCO Optical Upper Limits
  93. GRB 200306C: SAO RAS observations of OT
  94. GRB 200306C: GOTO upper limits
  95. GRB 200306A: Swift-XRT refined Analysis
  96. LIGO/Virgo S200302c: No notable candidates in GOTO imaging
  97. GRB 200306C: BOOTES-1 detection of the optical afterglow
  98. GRB 200306C: Swift detection of a burst with an optical counterpart
  99. Swift GRB200306.95: Global MASTER-Net OT detection
  100. Swift GRB200306.95: Global MASTER-Net OT detection

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