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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"
  1. GRB 171010B: Swift detection of a burst
  2. GRB 171011A: MASTER-SAAO optical observations
  3. GRB 171011A: Swift detection of a burst
  4. GRB 171010A: Fermi GBM observation
  5. GRB 171010A: LCO 1m telescope observations
  6. GRB171010A: AstroSat CZTI detection
  7. GRB 171010A: Swift-XRT afterglow detection
  8. GRB 171010A: optical observations
  9. GRB 171010A: OT, spectrum, and possible host galaxy
  10. GRB 171010A: Swift ToO observations
  11. GRB 171010A: Fermi-LAT detection
  12. GRB 171007A: Swift/UVOT Upper Limits
  13. LIGO/Virgo G298048/GW170817: updated localization from parameter estimation
  14. LIGO/Virgo G298048: Mid-Infrared Spitzer/IRAC Observations at 3.6 and 4.5 microns
  15. GRB 171007A: Swift-BAT refined analysis
  16. GRB 171007A: Fermi GBM observation
  17. GRB 171007A: Enhanced Swift-XRT position
  18. GRB 171007A: Swift-XRT refined Analysis
  19. GRB 171007A: RATIR Optical and NIR Observations
  20. GRB 171007A: Swift detection of a burst
  21. LIGO/Virgo G298048: LWA radio observations
  22. GRB 171004A: Swift/UVOT Upper Limits
  23. GRB 171004A: Swift-BAT refined analysis
  24. GRB 171004A: Correction to RATIR Astrometry and Photometry
  25. GRB 171004A: Swift-XRT refined Analysis
  26. GRB 171004A: Enhanced Swift-XRT position
  27. LIGO/Virgo G299232: SWASP optical imaging coverage
  28. GRB 171004A: RATIR Optical and NIR Observations
  29. GRB 170710A: LCO Observations
  30. GRB 171004A: Swift detection of a burst
  31. GRB 171003A: Enhanced Swift-XRT position
  32. LIGO/Virgo G299232: MAGIC Cherenkov Telescopes observations
  33. Swift Trigger 775946 is a Galactic transient, not GRB 171003
  34. LIGO/Virgo G299232: LOFAR follow-up
  35. GRB 171003A: LT early optical observations
  36. GRB 171003A: Swift detection of a burst or a Galactic Transient
  37. GRB 171001A: RATIR Optical and NIR Observations
  38. GRB 171001A: Swift-BAT refined analysis
  39. GRB 171001A: Nanshan-0.36m optical afterglow detections
  40. GRB 171001A: Swift-XRT refined Analysis
  41. GRB 171001A: Swift/UVOT Detection
  42. GRB 171001A: IRSF Observation
  43. GRB171001A: D50 optical limit
  44. GRB 171001A: Enhanced Swift-XRT position
  45. GRB 170921A: 15 GHz upper limits from AMI
  46. GRB 170903A: 15 GHz upper limits from AMI
  47. GRB 170906C: 15 GHz upper limits from AMI
  48. GRB 170823A: 15 GHz upper limits from AMI
  49. GRB 170822A: 15 GHz upper limits from AMI
  50. GRB 171001A: Swift detection of a burst
  51. LIGO/VIRGO G299232: AMI-LA Observations of the optical transient Swift J014008.5+343403.6
  52. Fermi Gamma-ray Burst Monitor trigger 528508320/170930994 is not a GRB
  53. Fermi Gamma-ray Burst Monitor trigger 528330888/170929011 is not a GRB
  54. 3.6m Devasthal Optical Telescope observations of GRB 170428A
  55. Further Swift-XRT observations of IceCube 170922A
  56. LIGO/Virgo G298048: Record of all e-MERLIN results to date on SSS17a
  57. LIGO/Virgo G298048: Further European VLBI Network (EVN) observations of SSS17a
  58. LIGO/Virgo G299232/GW170825: serendipitous XMM-Newton slew observations
  59. LIGO/Virgo G298936/GW170823: serendipitous XMM-Newton slew observations
  60. Fermi-GBM GRB misclassifications
  61. LIGO/VIRGO G298048: VLA detection of the radio counterpart at 6 GHz
  62. LIGO/Virgo G297595/GW170814: updated localization from parameter estimation
  63. LIGO/VIRGO G298048: Further MeerKAT observations of SSS17a
  64. GRB 170728B: Kottamia R-band observation
  65. LIGO/Virgo G298048: Summary of Pi of the Sky observations
  66. IceCube-170922A: Swift-XRT observations
  67. LIGO/VIRGO G298048: Latest 3 GHz Detection of Radio Counterpart to SSS17a
  68. LIGO/Virgo G298048: Limits from further FRB searches of SSS17a
  69. LIGO/Virgo G298048: MWA Observations of Error Region
  70. Konus-Wind observation of GRB 170921B
  71. Correction to GCN Circular 21919: GRB 170921C: Insight-HXMT detection
  72. IceCube-170922A: HAWC follow-up
  73. Search for counterpart to IceCube-170922A with ANTARES
  74. GRB 170921B: AstroSat CZTI detection
  75. GRB 170906A: Insight-HXMT detection
  76. LIGO/Virgo G298048: Effelsberg 100-m Radio Telescope observations of SSS17a
  77. GRB 170921C: Insight-HXMT detection
  78. IPN Triangulation of GRB 170921B
  79. INTEGRAL SPI-ACS observation of AMON IceCube-170922A
  80. IceCube-170922A - IceCube observation of a high-energy neutrino candidate event
  81. GRB 170921A: RATIR Optical Afterglow Detection and NIR Observations
  82. LIGO/Virgo G298048: SRT observations of SSS17a in NGC 4993
  83. GRB 170921A: Swift/UVOT Upper Limits
  84. GRB 170921A: Swift-BAT refined analysis
  85. GRB 170918A: Insight-HXMT detection
  86. GRB 170921A: LCO 2m telescope observations
  87. GRB 170921A: NOT optical observations
  88. LIGO/Virgo G298048: LCO FLOYDS and Gemini Spectroscopy
  89. GRB 170921A: Nanshan optical upper limit
  90. GRB 170921A: Enhanced Swift-XRT position
  91. GRB 170921A: MITSuME Okayama upper limits
  92. GRB 170921A: Swift-XRT refined Analysis
  93. GRB 170921A: TAROT Calern observatory optical observations
  94. GRB 170921B: Fermi GBM detection
  95. GRB 170921A: Swift detection of a burst
  96. LIGO/Virgo G298048: ATCA monitoring of SSS17a in NGC 4993
  97. LIGO/Virgo G298048: Limits from an FRB search of SSS17a with the Parkes 64m Radio Telescope
  98. LIGO/Virgo G298048: SSS17a photometry of CHILESCOPE observatory
  99. LIGO/Virgo G298048: Milliarcsecond imaging of the NGC 4993 central radio source
  100. Swift trigger 773082 is probably not astrophysical

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