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. GRB 210619A: BALROG localization (Fermi Trigger 645799548 / GRB 210619532)
  2. GRB 210619A: Fermi GBM Final Real-time Localization
  3. GRB 210618A: Swift/UVOT Upper Limits
  4. GRB 210618A: BOOTES-2/TELMA optical upper limit
  5. GRB 210618A: Swift-BAT refined analysis
  6. GRB 210618A: Fermi GBM observation
  7. GRB 210618A: Swift-XRT observations
  8. GRB 210618A: DDOTI upper limit for the optical afterglow
  9. GRB 210618A: Swift detection of a burst
  10. Swift GRB210618.07: Global MASTER-Net observations report
  11. GRB 210618A: Fermi GBM Final Real-time Localization
  12. GRB 210610B: Swift/UVOT Detection
  13. GRB 210610A: Swift/UVOT Detection
  14. GRB 210610B: CrAO/ZTSH continued optical observations and light curve
  15. Fermi trigger No 645485036: Global MASTER-Net observations report
  16. GRB 210610B: AbAO optical observations
  17. GRB 201008A: Fermi GBM observation
  18. GRB 210323B: Fermi GBM observation
  19. Fermi GRB 210615A: Global MASTER-Net observations report
  20. GRB 210615A: Fermi GBM Final Real-time Localization
  21. GRB 210610B: REM optical/NIR observations of the afterglow
  22. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  23. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  24. Swift ToO Observations of HAWC transient J0020+3108
  25. GRB 210605B: Swift-XRT afterglow detection
  26. GRB 210610A: Fermi GBM observations
  27. GRB 210610A: CAHA 2.2m Second Epoch
  28. GRB 210610B: iTelescope optical afterglow observations
  29. GRB 210610B: Further SAO RAS optical observations
  30. GRB 210610A: SAO RAS optical observations
  31. GRB 210610B: optical observations from Burke-Gaffney Observatory and Abbey Ridge Observatory
  32. GRB 210610B: Continued KAIT Optical Detection
  33. GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
  34. GRB 210421B: Fermi GBM detection
  35. Swift GRB210612.54: Global MASTER-Net observations report
  36. GRB 210607C: AstroSat CZTI detection
  37. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  38. GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
  39. GRB 210610B: MITSuME Akeno optical observation
  40. GRB 201228B: Fermi GBM observation
  41. GRB 210610B: VLA detection
  42. GRB 210610B: ALMA detection
  43. GRB 210610B: Liverpool Telescope optical photometry
  44. GRB 210610B: CrAO/ZTSH optical observations and light curve
  45. GRB 210610A: CrAO/ZTSH optical observations
  46. GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)
  47. GRB 210610A: CrAO/ZTSH optical observations
  48. GRB 210610A: CAHA 2.2m observations and light-curve behavior
  49. GRB 210606A: Fermi GBM detection
  50. GRB 210605B: Fermi GBM detection
  51. GRB 210610B: Swift-XRT refined Analysis
  52. GRB 210610B: Swift-BAT refined analysis
  53. GRB 210610B: Zwicky Transient Facility afterglow detection
  54. GRB 210610B: optical afterglow observations
  55. GRB 210610B: KAIT Optical Detection
  56. GRB 210610A: KAIT Optical Detection
  57. GRB 210607C: Insight-HXMT/HE detection
  58. GRB 210610B: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
  59. GRB 210610A: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
  60. GRB 210610B: Fermi GBM detection
  61. GRB 210610B: University of Siena Observatory optical photometry of the afterglow
  62. Konus-Wind detection of GRB 210610A
  63. Konus-Wind detection of GRB 210610B
  64. GRB 210610B: AGILE detection
  65. GRB 210610B: Redshift confirmation from GTC
  66. GRB 210610B: GOTO confirmation of afterglow detection
  67. GRB 210610A: Swift-XRT refined Analysis
  68. GRB 210610A: RATIR Optical and NIR Detection
  69. GRB 210610B: RATIR Optical and NIR Observations
  70. GRB 210610B: Enhanced Swift-XRT position
  71. GRB 210610B: Photometry and phot-redshift from Legacy Survey, PanSTAR, and SDSS
  72. GRB 210610B: SAO RAS optical observations
  73. GRB 210610A: Swift-BAT refined analysis
  74. GRB 210610A: 1.5m OSN optical observation
  75. GRB 210610B: correction to GCN 30181
  76. HAWC Transient Monitoring Alert: Significant Spot after 3 transits
  77. GRB 210610B: NOT optical observations and tentative redshift
  78. GRB 210610B: iTelescope optical afterglow observations
  79. GRB210610B: MeerLICHT multi-colour photometry
  80. Fermi trigger No 645047470: Global MASTER-Net observations report
  81. GRB 210610B: CrAO/ZTSh optical afterglow photometry
  82. GRB 210610B: BOOTES-2/TELMA optical observation
  83. Swift GRB 210610B: Global MASTER-Net observations report
  84. GRB 210610B: CrAO/ZTSh optical observations
  85. GRB 210610B: GIT optical detection
  86. Swift GRB210610.83: Global MASTER-Net OT detection
  87. GRB 210606A: Swift-XRT afterglow detection
  88. GRB 210610B: BALROG localization (Fermi Trigger 645047470 / GRB 210610827)
  89. GRB 210610B: Swift detection of a burst with bright optical afterglow
  90. GRB 210610A: MITSuME Ishigaki optical observation
  91. GRB210610A: MeerLICHT multi-colour photometry
  92. Swift GRB 210610A: Global MASTER-Net observations report
  93. Swift GRB 210610A: MASTER optical counterpart observation
  94. GRB 210610A: Enhanced Swift-XRT position
  95. GRB 210610A: Xinglong-2.16m redshift
  96. GRB 210610A: GIT optical detection
  97. GRB 210610A: Xinglong-2.16m optical afterglow observations
  98. GRB 210610A: MITSuME Akeno optical observation
  99. GRB 210610A: Swift detection of a burst with an optical counterpart
  100. GRB 210607B: Insight-HXMT/HE detection

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