Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  2. GRB 230307A: Bad Time Intervals for Fermi GBM data
  3. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  4. GRB 230328B: CAHA 2.2m/CAFOS detection
  5. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 230328B: 3.6m DOT multiband optical observation
  7. Fermi trigger No 701883729: Global MASTER-Net observations report
  8. GRB 230330B: Fermi GBM Final Localization
  9. Konus-Wind detection of GRB 230328B
  10. GRB 230328B: GRBAlpha detection
  11. GRB 230330A: Fermi GBM Final Real-time Localization
  12. GRB 230328B: Swift-BAT refined analysis
  13. GRB 230328B: Nanshan/NEXT 2nd optical observation
  14. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  15. GRB 230328B: Liverpool Telescope afterglow detection
  16. GRB 230328B: OHP/T120 optical observations
  17. GRB 230328B: GIT optical follow-up
  18. GRB 230328B: OASDG optical observations
  19. GRB 230328B: Nanshan/NEXT optical upper limit
  20. GRB 230328B: Swift-XRT refined Analysis
  21. GRB 230328B: AstroSat CZTI detection
  22. GRB 230328B: Fermi GBM observation
  23. GRB 230328B: Mondy, AbAO and Kitab optical observations
  24. GRB 230328B: Enhanced Swift-XRT position
  25. GRB 230328B: Mondy optical afterglow confirmation
  26. GRB 230328B: Swift detection of a burst with an optical afterglow
  27. GRB 230328B: Fermi GBM Final Real-time Localization
  28. Fermi GRB 230328A: Global MASTER-Net observations report
  29. GRB 230328A: Fermi GBM Final Real-time Localization
  30. GRB 230325A: Swift-BAT refined analysis
  31. GRB 230325A: Swift/UVOT Upper Limits
  32. GRB 230325A: X-shooter optical afterglow and redshift
  33. GRB 230325A: Swift-XRT refined Analysis
  34. GRB 230322B: Swift-BAT refined analysis
  35. GRB 230325A: Enhanced Swift-XRT position
  36. GRB 230325A: Prompt enhanced Swift-XRT position
  37. GRB 230325A: Swift detection of a burst
  38. GRB 230320B: Fermi GBM Observation
  39. Fermi trigger No 701313046: Global MASTER-Net observations report
  40. Fermi trigger No 701321709: Global MASTER-Net observations report
  41. GRB 230322B: Swift/UVOT Detection
  42. Konus-Wind detection of GRB 230309A
  43. Konus-Wind detection of GRB 230308A
  44. Konus-Wind detection of GRB 230304B
  45. GRB 230322B: Swift-XRT refined Analysis
  46. GRB 230322B: Enhanced Swift-XRT position
  47. Swift GRB 230322B: Global MASTER-Net observations report
  48. GRB 230322B: Swift detection of a burst with optical counterpart
  49. GRB 230322A: Fermi GBM Final Real-time Localization
  50. GRB 230320B: GRBAlpha detection
  51. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  52. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  53. Fermi trigger No 701071944: Global MASTER-Net observations report
  54. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  55. Fermi GRB 230320A: Global MASTER-Net observations report
  56. Fermi GRB 230321A: Global MASTER-Net observations report
  57. Fermi trigger No 701058254: Global MASTER-Net observations report
  58. SGR 1806-20: Correction to GCN 33494
  59. INTEGRAL detection of a burst from SGR 1806-200
  60. GRB 230321B: AstroSat CZTI detection
  61. GRB 230320B: AstroSat CZTI detection
  62. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  63. GRB 230321A: Fermi GBM Final Real-time Localization
  64. GRB 230320A: Fermi GBM Final Real-time Localization
  65. GRB 230314A: TURBO Optical Upper Limit
  66. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  67. Fermi trigger No 700976129: Global MASTER-Net observations report
  68. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  69. IPN triangulation of GRB 230309A
  70. Fermi GRB 230316A: Global MASTER-Net observations report
  71. GRB 230304D: AstroSat CZTI detection
  72. GRB 230316A: Fermi GBM Final Real-time Localization
  73. IPN triangulation of GRB 230304B
  74. GRB 230313A: AstroSat CZTI detection
  75. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  76. IPN triangulation of GRB 230308A (short/bright)
  77. Fermi GRB 230314A: Global MASTER-Net observations report
  78. GRB 230307A: ATCA radio detection
  79. GRB 230314A: Fermi GBM Final Real-time Localization
  80. VZLUSAT-2 detection of SGR 1806-20
  81. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  82. GRB 230307A: Swift/UVOT detection
  83. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  84. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  85. Fermi GRB 230313A: Global MASTER-Net observations report
  86. GRB 230313A: Fermi GBM Final Real-time Localization
  87. GRB 230307A: soft X-ray detection with LEIA
  88. GRB 230307A: Swift-XRT afterglow detection
  89. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  90. Swift GRB230311.85: Global MASTER-Net observations report
  91. Swift GRB230311.83: Global MASTER-Net observations report
  92. Further improved IPN localization for GRB 230307A
  93. Swift GRB230311.81: Global MASTER-Net observations report
  94. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  95. Swift GRB230311.84: Global MASTER-Net observations report
  96. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  97. Swift GRB230311.82: Global MASTER-Net observations report
  98. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  99. Alert from the HAWC Burst Monitor HAWC-230311A
  100. TESS Detection of the Optical Afterglow of GRB230307A

Advanced

Download all Circulars as a .tar.gz archive:
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