Skip to main content
Circulars over Kafka event name backfill. 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"

24603 results found.

  1. GRB 250421B: AstroSat CZTI detection of a bright long burst
  2. EP250421a: Einstein Probe detection of an X-ray transient
  3. EP250421a: Mephisto optical counterpart confirmation
  4. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  5. EP250421a: JinShan likely optical counterpart
  6. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  7. GRB 250419A: LCO optical observation
  8. GRB 250419A: JinShan optical observations
  9. GRB 250419A: SVOM/C-GFT optical observations
  10. GRB 250419A: Swift/UVOT Follow up
  11. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  12. GRB 250419A: LCO optical afterglow multi-band observations
  13. GRB 250419A: Mondy and AbAO Optical Observations
  14. GRB 250419A: AKO Optical Afterglow Detection
  15. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  16. GRB 250419A: Swift-XRT refined Analysis
  17. GRB 250419A: KAIT optical afterglow observations
  18. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  19. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  20. GRB 250419A: SVOM detection of a soft burst
  21. EP250416a: Swift/XRT counterpart fading
  22. EP20250416a: Swift/XRT counterpart detection
  23. IceCube-250416A: DDOTI Optical Observations
  24. EP250416a: Gemini South-GMOS optical counterpart
  25. SVOM/sb25041603 is not a GRB
  26. EP250416a: GSP optical upper limit
  27. EP250416a: Einstein Probe detection of an X-ray transient
  28. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  29. SVOM/sb25041603: SVOM detection of an X-ray transient
  30. IceCube 250414.324: DDOTI Optical Observations
  31. GRB 250413A: AstroSat CZTI detection
  32. EP250304a: ATCA radio observations
  33. EP250404a: Nanshan 0.43m Telescope optical observatios
  34. GRB 250411A: DDOTI Optical Observations
  35. Fermi GRB 250411A: Global MASTER-Net observations report
  36. GRB 250407A: Continued KAIT/Nickel optical observations
  37. GRB 250314A: e-MERLIN observations
  38. GRB 250407A: Mondy and AbAO Optical Observations
  39. EP250227a: Further NOT optical observations
  40. GRB 250320B: cubesat Avion detection
  41. IceCube-250406A: Swift-XRT observations
  42. GRB 250407A: LCO detection of a fading optical counterpart
  43. Fermi-LAT gamma-ray observations of IceCube-250406A
  44. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 250407A: SVOM/GRM observation of a bright long burst
  46. GRB 250407A: EP-WXT afterglow detection
  47. EP250407a: EP-WXT detection of a fast X-ray transient
  48. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  49. GRB 250407A: KAIT Optical Afterglow Candidate
  50. IceCube-250406A: No candidates from the Zwicky Transient Facility
  51. GRB 250407A: Fermi GBM Detection
  52. GRB 250407A: Swift-XRT afterglow detection
  53. GRB 250407A: SRG/ART-XC afterglow detection
  54. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  55. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  56. IPN triangulation of GRB 250406B (short/hard)
  57. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  58. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  59. IceCube 250406.951: DDOTI Optical Observations
  60. GRB 250406A: AstroSat CZTI detection
  61. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  62. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  63. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  64. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  65. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  66. Konus-Wind detection of GRB 250404A / EP250404a
  67. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  69. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  70. EP250402a: Optical upper limit with PD 1.3m observations
  71. GRB 250404A / EP250404a: NOT optical observations
  72. GRB 250331D: Swift-XRT afterglow detection
  73. GRB 250404B: AstroSat CZTI detection of a short burst
  74. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  75. EP250404a: REM optical/NIR observations
  76. EP250404a: Seimei/TriCCS optical counterpart detection
  77. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  78. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  79. EP250404a: LCO optical counterpart detection
  80. EP250404a: Xinglong decaying optical counterpart
  81. GRB 250403A: Montarrenti Observatory optical detection
  82. GRB 250404A: Fermi GBM Detection
  83. GRB 250403A: KAIT optical observations
  84. EP250404a: AKO Optical Afterglow Detection
  85. EP250404a: LAST detection of optical counterpart
  86. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  87. GRB 250403A: Fermi GBM observations
  88. GRB 250327B: VIRT Optical Upper Limit
  89. EP250404a: Mephisto multi-band optical detection
  90. GRB 250331C Swift-BAT refined analysis
  91. GRB 250331B Swift-BAT refined analysis
  92. GRB 250330A Swift-BAT refined analysis
  93. EP250321A: J band upper limit by SYSU 80cm telescope
  94. EP250404a: Nanshan/HMT optical counterpart detection
  95. EP250404a: Einstein Probe detection of an X-ray transient
  96. GRB 250403A: Swift/UVOT Detection
  97. GRB 250402A: Swift/UVOT Upper Limits
  98. EP250402a: Optical upper limit with Kinder observations
  99. GRB 250403A: REM NIR afterglow detection
  100. GRB 250403A: LCO optical counterpart detection

Advanced

Download all Circulars as a .tar.gz archive:
Looking for U.S. government information and services? Visit USA.gov