Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21131 results found.

  1. Fermi GRB 210515A: Global MASTER-Net observations report
  2. Swift GRB210514.71: Global MASTER-Net observations report
  3. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEM-210515A and 210515B
  4. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  5. Fermi trigger No 642538568: Global MASTER-Net observations report
  6. IceCube-210510A: not observable by Fermi-GBM
  7. Short GRB 210323A: likely host galaxy detection
  8. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  9. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  10. Fermi GRB 210511A: Global MASTER-Net observations report
  11. Fermi GRB 210511B: Global MASTER-Net observations report
  12. Fermi GRB 210510A: Global MASTER-Net observations report
  13. IceCube Alert 210510.20: Global MASTER-Net observations report
  14. GRB 210509A: Swift/UVOT Upper Limits
  15. Swift GRB 210509A: Global MASTER-Net observations report
  16. GRB 210509A: BOOTES-4/MET optical upper limit
  17. GRB 210509A: Swift-XRT observations
  18. Fermi GRB 210507A: Global MASTER-Net observations report
  19. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  20. ZTF21aayokph (AT2021lfa): continued Mondy optical observations
  21. Integral GRB210507.04: Global MASTER-Net observations report
  22. Integral GRB210506.78: Global MASTER-Net observations report
  23. GRB 210506A: Swift-XRT observations
  24. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF
  25. Alert from the HAWC Burst Monitor HAWC-210507A
  26. GRB 210506A: TNG NIR upper limits
  27. ZTF21aayokph (AT2021lfa): Mondy and Koshka observatory optical observations
  28. ZTF21aayokph (AT2021lfa): X-ray Detection with Swift/XRT
  29. Lowell Discovery Telescope Observations of ZTF21aayokph (AT2021lfa)
  30. ZTF21aayokph (AT2021lfa): Assy optical observations
  31. GRB 210506A: Swift ToO observations
  32. GRB 210506A: Swift/BAT-GUANO detection and possible arcminute localization of a short hard burst
  33. GRB 210504A: Lowell Discovery Telescope optical observations
  34. ZTF21aayokph (AT2021lfa): Redshift from Gemini South
  35. RATIR Observations of ZTF21aayokph (AT2021lfa)
  36. DDOTI Observations of ZTF21aayokph (AT2021lfa)
  37. ZTF and LT observations of ZTF21aayokph (AT2021lfa), a fast-fading red transient
  38. GRB 210504A: NOT optical afterglow detection
  39. GRB 210504A: Swift/UVOT Detection
  40. Swift GRB210504.58: Global MASTER-Net observations report
  41. Fermi GRB 210503A: Global MASTER-Net observations report
  42. Swift GRB210502.74: Global MASTER-Net observations report
  43. MAXI GRB210501.83: Global MASTER-Net observations report
  44. Fermi GRB 210501A: Global MASTER-Net observations report
  45. Fermi trigger No 641601187: Global MASTER-Net observations report
  46. Fermi GRB 210430B: Global MASTER-Net observations report
  47. Swift GRB210430.45: Global MASTER-Net observations report
  48. GRB 210413B: Swift/UVOT Observations
  49. Delayed GRB GCN Notices from Swift
  50. GRB 210323B: Swift-XRT observations
  51. Fermi GRB 210427A: Global MASTER-Net observations report
  52. GRB 210420B: Assy optical observations
  53. Fermi trigger No 640975205: Global MASTER-Net observations report
  54. GRB 210420B: Zeiss-1000 of Koshka optical observations
  55. GRB 210421B: Swift-XRT observations
  56. GRB 210420B: continued Tautenburg observations
  57. Swift GRB210422.74: Global MASTER-Net observations report
  58. GRB 210421A: Swift/UVOT Upper Limits
  59. GRB 210421B: Swift ToO observations
  60. GRB 210421B: Swift/BAT-GUANO detection and arcminute localization
  61. Fermi GRB 210421C: Global MASTER-Net observations report
  62. GRB 210420B: Montarrenti Observatory follow-up observations
  63. Fermi trigger No 640695289: Global MASTER-Net observations report
  64. GRB 210419C: Swift/UVOT Upper Limits
  65. GRB 210420B: Ondrejov D50 optical afterglow detection
  66. GRB 210420B: RATIR Optical and NIR Observations
  67. GRB 210420B: Tautenburg observations
  68. GRB 210420B: Swift/UVOT Detection
  69. GRB 210420B: KAIT Optical Observations
  70. Fermi GRB 210420A: Global MASTER-Net observations report
  71. GRB 210420B: Redshift from GTC
  72. GRB 210420B: Montarrenti Observatory optical afterglow detection
  73. Swift GRB 210421A: Global MASTER-Net observations report
  74. GRB 210420B: BOOTES-4/MET optical afterglow detection
  75. GRB 210420B: Optical observations
  76. GRB 210419C: Montarrenti Observatory Upper Limit
  77. GRB 210419A: Swift/UVOT Upper Limits
  78. Swift GRB210419.98: Global MASTER-Net observations report
  79. Fermi GRB 210419B: Global MASTER-Net observations report
  80. Swift GRB 210419A: Global MASTER-Net observations report
  81. GRB 210413B: Swift-XRT observations
  82. IceCube Alert 210416.09: Global MASTER-Net observations report
  83. GRB 210413B: Swift ToO observations
  84. GRB 210413B: Swift/BAT detection and probable localization of a short burst
  85. GRB 210410A: A twin of short GRB 090510 with complementary observations
  86. Fermi GRB 210415A: Global MASTER-Net observations report
  87. GRB 210411C: Swift/UVOT Detection
  88. GRB 210411C: Chilescope optical observations
  89. GRB 210411C: ePESSTO+ NTT optical observations
  90. Swift GRB 210411C: Global MASTER-Net observations report
  91. GRB 210411C: BOOTES-4/MET optical upper limit
  92. Fermi GRB 210411B: Global MASTER-Net observations report
  93. GRB 210406A: 10.4m GTC follow-up observation
  94. Fermi GRB 210411A: Global MASTER-Net observations report
  95. GRB 210410A: Swift/UVOT Upper Limits
  96. GRB 210406A: Swift-XRT observations
  97. GRB 210410A: RATIR Optical and NIR Observations
  98. Fermi GRB 210410A: Global MASTER-Net observations report
  99. GRB 210406A: Swift ToO observations
  100. GRB 210406A: Mondy optical upper limit

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