Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

32568 results found.

  1. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  2. EP250421a: Upper limits from Fermi-GBM Observations
  3. SVOM/sb25042207: XRT observations
  4. SVOM/sb25042207: BOOTES-2 early optical upper limit
  5. SVOM/sb25042207: GOTO optical upper limits
  6. GRB 250421A: AstroSat CZTI detection
  7. GRB250419A: VLA radio detection
  8. IceCube-250421A: DDOTI Detection of the LAST Candidate
  9. GRB 250419A: Mephisto Multi-band Optical Detection
  10. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  11. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  12. EP250421a: NOT optical observations
  13. GRB 250419A: Optical Observations via Virtual Telescope Project
  14. EP250421a: REM optical upper limit
  15. EP250421a: Swift/XRT counterpart detection
  16. EP250421A: COLIBRÍ Optical Upper Limit
  17. GRB 250419A: Mondy Continued Optical Observations
  18. Fermi GRB 250421A: Global MASTER-Net observations report
  19. EP250421a: Global MASTER-Net observations report
  20. EP250421a: Mephisto optical counterpart confirmation
  21. GRB 250419A: Liverpool Telescope observations
  22. GRB 250419A: LCO optical observation
  23. GRB 250419A: JinShan optical observations
  24. GRB 250419A: SVOM/VT optical continuous observations
  25. GRB 250419A: SVOM/C-GFT optical observations
  26. GRB 250419A: Swift/UVOT Follow up
  27. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  28. GRB 250419A: LCO optical afterglow multi-band observations
  29. GRB 250419A: Mondy and AbAO Optical Observations
  30. GRB 250419A: Liverpool Telescope observations
  31. GRB 250419A: AKO Optical Afterglow Detection
  32. GRB 250419A: MASTER optical afterglow observation
  33. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  34. GRB 250407A: rest-frame energetics from Konus-Wind observation
  35. GRB 250419A: Swift-XRT localisation
  36. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  37. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  38. GRB 250419A: Swift-XRT refined Analysis
  39. GRB 250419A: GOTO optical counterpart detection
  40. GRB 250419A: KAIT optical afterglow observations
  41. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  42. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  43. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  44. EP250416a: Swift/XRT counterpart fading
  45. EP250416a: refined EP-WXT and EP-FXT analysis
  46. Konus-Wind detection of GRB 250403A
  47. EP20250416a: Swift/XRT counterpart detection
  48. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  49. IceCube-250416A: DDOTI Optical Observations
  50. EP250416a: Gemini South-GMOS optical counterpart
  51. EP250225a: SVOM/VT optical brightening
  52. SVOM/sb25041603 is not a GRB
  53. EP250416a: GSP optical upper limit
  54. EP250416a: Global MASTER-Net observations report
  55. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  56. GRB 250413A: AstroSat CZTI detection
  57. EP250304a: ATCA radio observations
  58. EP250404a: Nanshan 0.43m Telescope optical observatios
  59. GRB 250411A: DDOTI Optical Observations
  60. Fermi GRB 250411A: Global MASTER-Net observations report
  61. GRB 250407A: Continued KAIT/Nickel optical observations
  62. GRB 250314A: e-MERLIN observations
  63. GRB 250407A: Mondy and AbAO Optical Observations
  64. EP250227a: Further NOT optical observations
  65. GRB 250320B: cubesat Avion detection
  66. IceCube-250406A: Swift-XRT observations
  67. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  68. IPN triangulation of GRB 250407A
  69. EP250407a: Global MASTER-Net observations report
  70. GRB 250407A: LCO detection of a fading optical counterpart
  71. Fermi-LAT gamma-ray observations of IceCube-250406A
  72. EP250407a: Swift-XRT observations
  73. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  74. Konus-Wind detection of GRB 250407A
  75. GRB 250407A: SVOM/GRM observation of a bright long burst
  76. GRB 250407A: EP-WXT afterglow detection
  77. EP250407a: EP-WXT detection of a fast X-ray transient
  78. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  79. GRB 250407A: KAIT Optical Afterglow Candidate
  80. IceCube-250406A: No candidates from the Zwicky Transient Facility
  81. GRB 250407A: Fermi GBM Detection
  82. GRB 250407A: Swift-XRT afterglow detection
  83. Fermi GRB 250407A: Global MASTER-Net observations report
  84. GRB 250407A: Swift ToO observations
  85. GRB 250407A: SRG/ART-XC afterglow detection
  86. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  87. Konus-Wind detection of GRB 250406B (short/hard)
  88. IPN triangulation of GRB 250406B (short/hard)
  89. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  90. GRB 250406A: AstroSat CZTI detection
  91. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  92. Fermi GRB 250406A: Global MASTER-Net observations report
  93. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  94. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  95. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  96. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  97. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  98. Konus-Wind detection of GRB 250404A / EP250404a
  99. GRB 250404A / EP250404a: Mondy optical observations
  100. EP250404a: refined analysis of the EP-WXT and EP-FXT observations

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