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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"

19565 results found.

  1. IPN Triangulation of GRB 170921B
  2. INTEGRAL SPI-ACS observation of AMON IceCube-170922A
  3. GRB 170921A: RATIR Optical Afterglow Detection and NIR Observations
  4. LIGO/Virgo G298048: SRT observations of SSS17a in NGC 4993
  5. GRB 170921A: Swift/UVOT Upper Limits
  6. GRB 170921A: NOT optical observations
  7. LIGO/Virgo G298048: LCO FLOYDS and Gemini Spectroscopy
  8. GRB 170921A: Nanshan optical upper limit
  9. GRB 170921A: Enhanced Swift-XRT position
  10. GRB 170921A: MITSuME Okayama upper limits
  11. GRB 170921A: Swift-XRT refined Analysis
  12. GRB 170921A: TAROT Calern observatory optical observations
  13. GRB 170921A: Swift detection of a burst
  14. LIGO/Virgo G298048: ATCA monitoring of SSS17a in NGC 4993
  15. LIGO/Virgo G298048: Milliarcsecond imaging of the NGC 4993 central radio source
  16. LIGO/Virgo G298048: ATLAS pre-discovery limits 601 to 16 days before first detection of SSS17a/DLT17ck
  17. LIGO/Virgo G298048: AST3-2 observations of SSS17a/DLT17ck from Antarctica
  18. LIGO/Virgo G298048: ATCA monitoring of SSS17a in NGC 4993
  19. GRB 170912B: Swift/UVOT Upper Limits
  20. GRB 170912A: Swift-XRT refined Analysis
  21. LIGO/Virgo G299232: Khureltogot observations
  22. GRB 170912A: Swift/UVOT Upper-Limits
  23. GRB 170912B: Enhanced Swift-XRT position
  24. LIGO/Virgo G299232: Pierre Auger Observatory follow-up
  25. LIGO/Virgo G298389: Pierre Auger Observatory neutrino follow-up
  26. GRB 170912B: Swift detection of a burst
  27. GRB 170912A: Enhanced Swift-XRT position
  28. GRB 170912A: Swift detection of a burst
  29. LIGO/Virgo G298048: VLBA upper limits at 8.7GHz for the GW counterpart SSS17a/DLT17ck on August 20-21 UT
  30. GRB 170906A: Swift/UVOT Detection
  31. GRB 170906B: Swift/UVOT Upper Limits
  32. LIGO/Virgo G299232: Swift-XRT sources
  33. GRB 170906C: optical observations
  34. GRB 170906C: COATLI Observations
  35. GRB 170906C: Swift/UVOT Upper Limits
  36. GRB 170906C: Enhanced Swift-XRT position
  37. GRB 170906C: Swift-XRT observations
  38. GRB 170906A: REM optical/NIR observations
  39. GRB 170906A: Enhanced Swift-XRT position
  40. GRB 170906B: Enhanced Swift-XRT position
  41. GRB 170906B: Swift detection of a burst
  42. GRB 170906A: Swift detection of a burst with an optical afterglow
  43. IPN Triangulation of GRB 170904A (long/very bright)
  44. LIGO/VIRGO G298048: Radio detection of SSS17a at 6 GHz with the VLA
  45. LIGO/VIRGO G298048: Radio detection of SSS17a at 3GHz with the VLA/JAGWAR
  46. LIGO/Virgo G299232: Maidanak observations of optical transient SwiftJ014008.5+343403.6
  47. LIGO/Virgo G299232: LOFAR follow-up
  48. GRB 170827A: LCO Observations
  49. GRB 170903A: Swift/UVOT Upper Limits
  50. GRB 170903A: UAFO /ISON optical upper limit
  51. LIGO/Virgo G298048: e-MERLIN upper limits on 5 GHz compact emission from SSS17a
  52. LIGO/Virgo G298048: ATCA monitoring of SSS17a in NGC 4993
  53. LIGO/Virgo G299232: RoboPol observations of MASTER OT J033744.97+723159.0
  54. GRB 170903A: MITSuME Okayama upper limits
  55. GRB 170903A: Host galaxy redshift from OSIRIS/GTC
  56. LIGO/Virgo G298048: Chandra X-ray Update on GW170817
  57. GRB 170903A: Enhanced Swift-XRT position
  58. GRB 170903A: Nanshan optical upper limit
  59. GRB 170903A: Swift-XRT observations
  60. Swift Triggers on MAXI J1535-571
  61. GRB 170902A: Enhanced Swift-XRT position
  62. LIGO/Virgo G297595: DECam observations of BBH merger region of interest
  63. GRB 170902A: Swift detection of a burst or possible Galactic transient
  64. LIGO/Virgo G298048: Chandra monitoring of the X-ray emission from SSS17a
  65. LIGO/Virgo G298048: Continued X-ray monitoring and X-ray detection of GW170817 [erratum]]
  66. LIGO/Virgo G298048
  67. LIGO/Virgo G298048: Hubble Space Telescope observations
  68. LIGO/Virgo G299232: GRAWITA Asiago optical observations
  69. LIGO/Virgo G299232: continued WHT observations of the field of SwiftJ014008.5+343403.6
  70. LIGO/Virgo G298048: Discovery of X-ray emission from SSS17a in NGC4993
  71. GRB 170830A: iTelescope optical observations
  72. LIGO/Virgo G299232: HAWC follow-up
  73. LIGO/Virgo G299232 : RATIR Optical and NIR Observations of Swift UVOT source
  74. LIGO/Virgo G299232: WHT non-detection u-band optical transient
  75. LIGO/Virgo G299232: Liverpool Telescope observations
  76. LIGO/Virgo G299232: observations of the optical Transient Discovered by Swift/UVOT
  77. IPN Triangulation of GRB 170826B
  78. LIGO/Virgo G299232: PIRATE observations of MASTER OT J033744.97+723159.0
  79. LIGO/Virgo G299232/PGWB170825.55: early MASTER observations of the Swift UVOT source position
  80. LIGO/Virgo G298048: ALMA observations
  81. LIGO/Virgo G299232: GRAWITA Asiago/Copernico Telescope observations
  82. GRB170827A: Further GROND follow-up observations
  83. LIGO/Virgo G299232: COATLI Observations of MASTER OT J033744.97+723159.0
  84. IPN Triangulation of GRB 170827B (short)
  85. LIGO/Virgo G298936: HAWC follow-up
  86. GROND observations of GRB170827A
  87. GRB 170827A: ePESSTO NTT afterglow candidate
  88. GRB 170823A: TAROT Calern observatory optical observations
  89. LIGO/Virgo G299232: OVRO-LWA simultaneous low frequency radio observations of localization region
  90. LIGO/Virgo G299232: LOFAR follow-up
  91. GRB 170827A: Swift/UVOT Upper Limits
  92. GRB 170827A: REM optical/NIR observations
  93. GRB 170827A: Swift detection of a burst
  94. LIGO/Virgo G299232: CALET Observations
  95. LIGO/VIRGO G299232: Fermi GBM Observations
  96. LIGO/Virgo G299232 : Fermi-LAT search for high-energy gamma-ray counterpart
  97. LIGO/Virgo G298389: HAWC follow-up
  98. LIGO/Virgo G298936: CALET Observations
  99. GRB 170820A CALET Gamma-Ray Burst Monitor detection
  100. LIGO/Virgo G299232: Swift/BAT data search

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