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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"

20554 results found.

  1. LIGO/Virgo G284239: IceCube neutrino observations
  2. GRB 170428A: GTC spectroscopic redshift of candidate host galaxy
  3. GRB 170428A: 15 GHz upper limits from AMI
  4. Swift Trigger 748858: 15 GHz upper limits from AMI
  5. GRB 170428A: TNG optical observations
  6. Short GRB 170428A: MASTER-OAFA final reduction of the optical observations
  7. GRB 170428A: DCT Imaging
  8. GRB 170428A: TAROT La Silla observatory optical observations
  9. GRB 170428A: RATIR Afterglow Confirmation
  10. GRB 170428A: GROND detection of the afterglow
  11. GRB 170428A: Swift/UVOT Upper Limits
  12. GRB 170428A: Xinglong 2.16-m upper limit and host galaxy candidate
  13. GRB 170428A: MASTER-OAFA early optical observations
  14. Swift Trigger 750337 is probably a noise fluctuation
  15. Swift Trigger 750096 is probably a noise fluctuation
  16. GRB 170424A: LCO Observations
  17. GRB 170419A: Swift/UVOT Upper Limits
  18. GRB 170424A: Tiled Swift observations
  19. GRB 170419A: LCO Observations
  20. Swift Trigger 748858: AbAO and TSHAO optical observations
  21. Swift Trigger 748858: TAROT La Silla observatory optical observations
  22. Swift Trigger 748858: RATIR Optical and NIR Observations
  23. GRB 170419B: Zadko observatory - Gingin optical observations
  24. GRB 170419A: Zadko observatory - Gingin optical observations
  25. Swift trigger 748858: Swift BAT, XRT, and UVOT refined analysis
  26. Swift Trigger 748858: MASTER-OAFA early optical observations
  27. Swift Trigger 748858: Zadko observatory - Gingin optical observations
  28. LIGO/Virgo G275404: DLT40 follow-up observation
  29. GRB 170409A: TAROT Reunion observatory optical observations
  30. GRB 170405A: SMARTS optical/IR afterglow observations
  31. GRB 170317A: SAO RAS optical observations
  32. GRB170405A, Swift-UVOT Detection
  33. GRB 170405A: Etelman observatory optical observations
  34. GRB 170405A: RATIR Optical and NIR Observations
  35. GRB 170405A: LCO FTN observations
  36. GRB 170405A: ISON/Terskol optical observations
  37. GRB 170405A: Watcher optical detection
  38. GRB 170405A: TAROT Reunion observatory optical observations
  39. GRB 170405A: NOT optical observations
  40. LIGO/Virgo G275404: European VLBI Network (EVN) follow-up of the near-IR transient in the AGL J1914+1043 field
  41. GRB 170325A: optical observations, possible OT/host detection
  42. Fermi-LAT Gamma-ray Observations of IceCube-170321
  43. Swift triggered on SAX J1806.5-221
  44. GRB 170331A: Swift/UVOT Upper Limits
  45. IceCube-170321A: Swift-XRT observations
  46. GRB 170330A: Swift/UVOT Detection of a Fading Afterglow
  47. GRB 170325A: 15 GHz upper limits from AMI
  48. GRB 170318B: 15 GHz upper limits from AMI
  49. GRB 170318A: 15 GHz upper limits from AMI
  50. GRB 170317A: 15 GHz upper limits from AMI
  51. GRB 170330A: LCO Cerro Tololo observations
  52. LIGO/Virgo G275697: LOFAR follow-up
  53. GRB 170331A: LCO Sutherland observations
  54. Fermi trigger 512347439/GRB 170327A: MASTER-SAAO possible OT detection
  55. LIGO/Virgo G277583: Konus-Wind observations
  56. INTEGRAL pointed follow-up of IceCube-170321A
  57. LIGO/Virgo G277583: Fermi GBM Observations
  58. LIGO/Virgo G277583: INTEGRAL search for an X-ray and gamma-ray counterpart
  59. LIGO/Virgo G275697: AMI Large Array Search for a Radio Afterglow
  60. GRB 170318A: KAIT Optical Upper Limit
  61. GRB 170317A: Mondy optical observations
  62. GRB 170318B: RATIR Optical and NIR Observations
  63. GRB 170317A: RATIR Optical and NIR Observations
  64. GRB 170318B: Swift/UVOT Upper Limits
  65. LIGO/Virgo G277583: CALET Observations
  66. GRB 170318A: RATIR Optical and NIR Observations
  67. GRB 170318A: Swift/UVOT Upper Limits
  68. GRB 170317A: RATIR Optical and NIR Observations
  69. IceCube-170312A: MASTER follow-up observations
  70. LIGO/Virgo G277583: Asiago spectroscopic classification of ATLAS17byo and ATLAS17cgg
  71. GRB 170317A: LCO FTN observations
  72. LIGO/Virgo G277583 : MAXI/GSC observations
  73. GRB 170317A: Swift/UVOT Detection
  74. GRB 170317A: Mondy optical observations
  75. GRB 170317A: MITSuME Okayama Ks-band upper-limit
  76. IceCube-170312A: Swift-XRT observations
  77. GRB 170317A: GMG observation
  78. LIGO/Virgo G275697: Swift-XRT source 23 no longer fading
  79. LIGO/Virgo G277583: Discovery Channel Telescope Follow-Up of ATLAS17cck
  80. LIGO/Virgo G277583: ATLAS coverage and transients over the first 2 days
  81. GRB 170307A: 15 GHz upper limit from AMI
  82. LIGO/Virgo G277583: GROND follow up of ATLAS17cck
  83. LIGO/Virgo G277583: ATLAS17cck - a fast declining transient
  84. LIGO/Virgo G277583: ERRATUM LV GCN 20871: TAROT Calern (TCA) observations
  85. LIGO/Virgo G277583: TAROT Calern (TCA) observations
  86. LIGO/Virgo G277583: SVOM/Mini-GWAC observations of the initial skymap
  87. LIGO/Virgo G275404: Medicina radio follow-up of near-infrared
  88. LIGO/Virgo G277583: AGILE GRID observations
  89. LIGO/Virgo G277583: AGILE MCAL observations
  90. LIGO/Virgo G270580: optical observations and classification of PS and MASTER sources
  91. LIGO/Virgo G277583: IceCube neutrino observations
  92. GRB 170311A: VLT observations
  93. INTEGRAL observation of IceCube HESE 65274589 129281
  94. LIGO/Virgo G275697: GRAWITA NOT optical observations of Swift/XRT Source 23
  95. GRB 170311A: Further GROND analysis
  96. GRB 170311A: Swift/UVOT Upper Limits
  97. SN MASTER OT J042250.16-820415.4 is the possible optical counterpart of the gravitational waves event LIGO/Virgo G274296
  98. GRB 170311A: GROND upper limits
  99. GRB 170311A: MASTER-OAFA early optical observations
  100. GRB170306A: SALT observations

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