Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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. Fermi GRB 200619B: Global MASTER-Net observations report
  2. GRB 200619B: AstroSat CZTI detection
  3. GRB 200619A: Fermi GBM observation
  4. Fermi trigger No 614239407: Global MASTER-Net observations report
  5. GRB 200619A: AGILE detection
  6. LIGO/Virgo MS200618aq: Retraction of a test binary neutron star candidate
  7. LIGO/Virgo MS200619bf: Retraction of a test binary neutron star candidate
  8. LIGO/Virgo MS200618bx: Retraction of a test binary neutron star candidate
  9. LIGO/Virgo MS200618bq: Retraction of a test binary neutron star candidate
  10. GRB 200619B: Fermi GBM Final Real-time Localization
  11. GRB 200619A: Insight-HXMT/HE detection
  12. Fermi trigger No 614226976: Global MASTER-Net observations report
  13. GRB 200613A: continued Kitab optical observations
  14. GRB 200613A: SAO RAS optical observations
  15. GRB 200617A: Insight-HXMT/HE detection
  16. IceCube-200530A - SN2020lls likely unrelated
  17. Swift/UVOT Observations of IceCube 200615A
  18. GRB 200613A: Mondy optical observations
  19. LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
  20. Fermi trigger No 614103490: Global MASTER-Net observations report
  21. Baksan Neutrino Observatory Alert 200617.47: Global MASTER-Net observations report
  22. GRB 200615B: CALET Gamma-Ray Burst Monitor detection
  23. Swift-XRT observations of IceCube 200615A
  24. IceCube-200615A: No significant detection in HAWC
  25. GRB 200613A: Jet-break from Xinglong-2.16m optical observations
  26. Fermi-LAT Gamma-ray Observations of IceCube-200615A
  27. IceCube-200614A: No significant detection in HAWC
  28. IceCube-200615A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 200616B: Fermi GBM Final Real-time Localization
  30. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  31. LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate
  32. GRB 200613A: CALET Gamma-Ray Burst Monitor detection
  33. LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
  34. GRB 200613A: MITSuME Akeno optical upper limits
  35. Fermi GRB 200616A: Global MASTER-Net observations report
  36. GRB 200615B: MAXI/GSC detection
  37. GRB 200616A: Fermi GBM Final Real-time Localization
  38. GRB 200613A: continued AbAO optical afterglow observations
  39. IceCube-200615A: Upper limits from Fermi-GBM Observations
  40. IceCube-200614A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-200614A: not observable by Fermi-GBM
  42. IceCube-200615A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  43. IceCube Alert 200615.62: Global MASTER-Net observations report
  44. IceCube-200614A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  45. LIGO/Virgo MS200615h: Retraction of a test binary neutron star candidate
  46. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  47. GRB 200613A: Continued Xinglong-2.16m optical observations
  48. Fermi GRB 200615A: Global MASTER-Net observations report
  49. GRB 200615A: Fermi GBM Final Real-time Localization
  50. Baksan Neutrino Observatory Alert 200614.34: Global MASTER-Net observations report
  51. IceCube Alert 200614.53: Global MASTER-Net observations report
  52. GRB 200613A: Swift/UVOT Detection
  53. GRB 200613A: Xinglong-2.16m optical observations
  54. Fermi GRB 200614A: Global MASTER-Net observations report
  55. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  56. GRB 200614A: Fermi GBM Final Real-time Localization
  57. GRB 200613A: Liverpool Telescope observations
  58. GRB 200613A: OAJ Afterglow: Error in Coordinates
  59. GRB 200613A: Kitab and AbAO optical afterglow observations, host galaxy candidate
  60. GRB 200613A: Swift-XRT afterglow detection
  61. GRB 200613A: Candidate afterglow from OAJ
  62. GRB 200612A: Fermi GBM detection
  63. Fermi GRB 200613A: Global MASTER-Net observations report
  64. GRB 200613A: Swift ToO observations
  65. GRB 200613A: Fermi-LAT detection
  66. GRB 200613A: Fermi GBM observation
  67. GRB 200612A: Swift/UVOT Upper Limits
  68. Baksan Neutrino Observatory Alert 200611.74: Global MASTER-Net observations report
  69. BALROG localization (Fermi Trigger 613719013 / GRB 200613229)
  70. GRB 200613A: Fermi GBM Final Real-time Localization
  71. GRB 200612A: Swift-BAT refined analysis
  72. GRB 200612A: Swift-XRT refined Analysis
  73. Konus-Wind observation of ultra-long GRB 200612A
  74. GRB 200612A: Enhanced Swift-XRT position
  75. GRB 200612A: Late Optical Maximum Deteted by MASTER
  76. GRB 200612A: BOOTES-3/YA optical upper limit
  77. Fermi trigger No 613630183: Global MASTER-Net observations report
  78. Swift GRB200612.19: Global MASTER-Net OT detection
  79. Swift GRB200612.19: Global MASTER-Net observations report
  80. GRB 200612A: Swift detection of a burst
  81. GRB 200609A: Insight-HXMT/HE detection
  82. GRB 200608A: Swift-BAT refined analysis
  83. Konus-Wind detection of GRB 200605A
  84. GRB 200605A: CALET Gamma-Ray Burst Monitor detection
  85. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  86. GRB 200609A: Fermi GBM Final Real-time Localization
  87. Swift GRB 200608A: Global MASTER-Net observations report
  88. GRB 200608A: BOOTES-3 and BOOTES-4 optical upper limit
  89. GRB 200608A: Swift detection of a burst
  90. GRB 200607B: AstroSat CZTI detection
  91. GRB 200522A: Further HST F125W Observations
  92. Fermi GRB 200607B: Global MASTER-Net observations report
  93. GRB 200607B: Fermi GBM Final Real-time Localization
  94. Fermi GRB 200607A: Global MASTER-Net observations report
  95. IPN triangulation of GRB 200605A (short)
  96. GRB 200607A: Fermi GBM Final Localization
  97. GRB 200607A: BALROG localization (Fermi Trigger 613212114 / GRB 200607362)
  98. GRB 200530A: Fermi GBM detection
  99. GRB 200530A: CALET Gamma-Ray Burst Monitor detection
  100. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov