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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"

2623 results found.

  1. LIGO/Virgo S190425z: SAGUARO follow-up observations
  2. LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
  3. GRB 190326A: Swift XRT and UVOT follow-up observations
  4. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  5. LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
  6. IceCube-190331A: Swift-XRT Follow-up Observations
  7. GRB 190409A: ground analysis reveals a likely spurious event
  8. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  9. GRB 190409A: Swift detection of a possible burst
  10. LIGO/Virgo S190408an: SAGUARO follow-up observations
  11. Swift GRB 190331B: Further Swift-XRT observations
  12. GRB 190331B: Swift observations of a ground-detected burst
  13. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  14. Further Chandra observations of GW170817 ~581-583 days since merger
  15. Swift detection of LS I +61 303
  16. Correction: Chandra observations of GW170817 ~581 days since merger
  17. Chandra observations of GW170817 ~581 days since merger
  18. GRB 190206A: AstroSat CZTI detection
  19. GRB 190203A: Swift-BAT refined analysis
  20. GRB 190204A: Swift detection of a burst with a possible optical counterpart
  21. GRB 190202A: LCO-CTIO optical observations
  22. GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
  23. GRB 190129B: GROND possible host candidate
  24. IceCube-190124A - IceCube observation of a high-energy neutrino candidate event
  25. GRB 190114C: GMRT detection at 1.26GHz
  26. Swift ToO Instructions Update
  27. Swift ToO Website Down
  28. GRB 190114C: RATIR Optical and NIR Detections
  29. GRB 190114C: COATLI Optical Detection
  30. GRB 190114B, Swift-BAT refined analysis
  31. GRB 190114C: SPI-ACS/INTEGRAL extended emission detection
  32. GRB 190114C: Possible host galaxy in Pan-STARRS
  33. GRB 190114B: Swift detection of a burst
  34. GRB 190114A: Possible UVOT Detection
  35. GRB 190106A: optical observations, possible jet break detection
  36. Correction to the GCN circ. 23654 / GRB 190109B: Mondy optical upper limit
  37. GRB 190106A: GMG spectral results
  38. GRB 181228A: possible NOT optical detection
  39. FRB 181228: Global MASTER Net optical inspection
  40. Swift Trigger 878504 is not astrophysical
  41. MASTER: OTs detection during Fermi alert trigger 565936249 early observations
  42. GRB 181201A: VLT/FORS2 tentative spectroscopic redshift
  43. Short-duration GRB 181121.4: MASTER-Tavrida possible OT detection near the PGC galaxy during large Fermi error box inspection
  44. GRB 181123B: Keck near-infrared imaging
  45. GRB 181110A: Kanata 1.5m optical observation
  46. Fermi GRB 181105.31: Global MASTER Net optical observations
  47. GRB 181030A: Swift detection of a burst with a possible optical counterpart
  48. IceCube-181023A - IceCube observation of a high-energy neutrino candidate event
  49. GRB 181020A: Global MASTER Net OT observations
  50. IceCube-181014A - IceCube observation of a high-energy neutrino candidate event
  51. IceCube-180908A - IceCube observation of a high-energy neutrino candidate event
  52. GRB 180828A: Swift detection of a GRB or possible Galactic Transient Swift J1754.9-2548
  53. GRB 180728A: discovery of the associated supernova
  54. Swift Trigger 852625: Swift/BAT/XRT/UVOT observations
  55. GRB 180809B: CALET Gamma-Ray Burst Monitor detection
  56. Swift Trigger 852625: a possible GRB
  57. GRB 180806.94: MASTER possible OT detection in Fermi GMB trigger 555287944 error box
  58. GMRT radio detection of GRB 180720B
  59. GRB 180728B: GOTO optical search over IPN region
  60. GRB 180728B: MASTER optical observations short GRB IPN error box
  61. GRB 180720C: Swift detection of a burst or possible Galactic Transient
  62. GRB 180720B: LCO Haleakala possible bright optical candidate
  63. GRB 180715A: LCO Sutherland possible optical candidate
  64. GRB 180705A: OSN observations
  65. Konus-Wind observation of GRB 180704A
  66. GRB 180703A: LCO Sutherland possible optical candidate
  67. GRB150101B: INTEGRAL prompt gamma-ray signal from a possible GRB170817A-analogue
  68. GRB 180626C : GOTO optical observations
  69. GRB 180626B : GOTO optical observations
  70. GRB 180613A: Possible IR afterglow
  71. GRB 180613A: Possible host galaxy at XRT position, or star
  72. GRB 180529A: CALET Gamma-Ray Burst Monitor detection
  73. AGILE/MCAL detection of GRB 180529 and a possible precursor
  74. Swift Trigger 831888: a possible GRB or Galactic transient
  75. GRB 180510B: Swift detection of a burst with an optical counterpart
  76. Chandra observations of GW170817 reveal a fading afterglow
  77. Chandra observations of GW170817 260 days since merger: first statistically significant evidence for an X-ray decay
  78. GRB 180418A GROND observations
  79. Chandra observations of GRB161219B 400 days after the explosion
  80. Swift Trigger 819301: possible GRB 180329A
  81. GRB 180324A: RATIR Optical Observations and Possible Afterglow Detection
  82. GRB 180316A: RATIR Optical Observations, Possible Re-brightening
  83. GRB 180224A: AbAO optical observations
  84. Swift trigger 811074 (possible GRB 180221A): Swift refined analysis
  85. GRB180221A: MASTER-OAFA optical observations
  86. Swift Trigger 811074: possible GRB 180221A
  87. Trigger 809374: Swift detection of a possible non-burst faint source
  88. Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
  89. LIGO/Virgo GW170817: Chandra X-ray Emission Continues to Rise ~156 Days Post-Merger
  90. GRB 180120A CALET Gamma-Ray Burst Monitor detection
  91. GRB180111A: Xinglong TNT possible optical detection
  92. GRB 180103A: LCO Sutherland 1-m telescope observations
  93. GRB 171209A: Swift/UVOT Analysis of the burst
  94. GRB 171209A: Swift detection of a burst
  95. LIGO/Virgo G298048: Brightening X-ray Emission from GW170817/GRB170817A/SSS17a
  96. LIGO/Virgo GW170817: Chandra X-ray brightening of the counterpart 108 days since merger
  97. GRB 171205A: Host galaxy photometric properties
  98. Possible blackbody component in the X-ray spectrum of GRB171205A
  99. Pan-STARRS follow-up of IceCube-171106A
  100. GRB 171123A: Swift detection of a burst

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