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"

20418 results found.

  1. GRB 260515A: OHP/T193 optical observations
  2. EP260514a: COLIBRÍ optical upper limits
  3. GRID detection of GRB 260507A
  4. GRB 260515A: LCO optical observations
  5. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  6. GRB 260515A: SVOM/VT optical candidate from VHF data
  7. GRB 260515A: JinShan optical counterpart candidate
  8. GRB 260515A: SVOM detection of a burst
  9. EP260514a: GROWTH-India Telescope optical upper limit
  10. GRB 260511B: GMG Optical Upper Limit
  11. EP260514a: Einstein Probe detection of a fast X-ray transient
  12. EP260512a: LCO optical upper limits
  13. GRB 260511B: Mephisto multi-band optical followup
  14. EP260512a: EP-FXT follow-up observation
  15. EP260507a: Xinglong Schmidt optical counterpart detection
  16. GRB 260511B: further SAO RAS optical observations
  17. EP260512a: COLIBRÍ optical upper limits
  18. EP260512a: Einstein Probe detection of an X-ray transient
  19. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  20. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  21. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  22. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  23. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  24. MASS-Cube (GRID 2.0) detection of GRB 260511A
  25. MASS-Cube (GRID 2.0) detection of GRB 260507A
  26. GRB 260511B: SAO RAS optical observations
  27. GRB 260511B: FRAM-ORM optical detection
  28. GRB 260511B: LCO optical counterpart detection
  29. GRB260511B: MAO/AZT-22 optical observations
  30. GRB 260511B: LCO optical observations
  31. GRB 260511B: OHP/T193 spectroscopic observations
  32. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  33. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. GRB 260509A: SAO RAS optical observations
  35. GRB 260511A: REM near-infrared detection
  36. GRB 260511B: GROWTH-India Telescope optical observations
  37. GRB 260511B: AstroSat CZTI detection
  38. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  39. GRB 260511B: SVOM/VT optical observation with VHF data
  40. GRB 260511B: TRT optical observation
  41. GRB 260510B: SVOM/ECLAIRs refined analysis
  42. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  43. GRB 260511B SVOM/C-GFT optical counterpart detection
  44. EP260509a: LCO optical upper limits
  45. GRB 260511A: UTGO H50 optical afterglow observation
  46. GRB 260511B: SVOM detection of a burst
  47. EP260509a: EP-FXT non-detection and upper limit
  48. GRB 260511A: SVOM/VT optical observation with VHF data
  49. GRB 260511A: KAIT optical afterglow observations
  50. GRB 260511A: LCO optical afterglow detection
  51. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  52. GRB 260511A: TRT optical counterpart detection
  53. GRB 260511A: SVOM detection of a bright burst
  54. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  55. GRB 260510B: GOTO early upper limit
  56. GRB 260510C: SVOM detection of a burst
  57. GRB 260510B: LCO optical upper limits
  58. EP260509a: Einstein Probe detection of an X-ray transient
  59. GRB 260509A: Liverpool Telescope optical observations
  60. GRB 260510B: SVOM detection of a burst
  61. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  62. GRB 260509A: LCO optical observations
  63. SVOM GRB 260509A: MASTER-OAFA optical observation
  64. GRB 260509A: KAIT optical observations
  65. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  66. GRB 260509A: SVOM/VT optical candidate with VHF data
  67. GRB 260509A: LCO optical counterpart detection
  68. GRB 260509A: SVOM detection of a burst
  69. GRB 260506B: AstroSat CZTI detection
  70. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  71. EP260507a: REM optical/NIR observations
  72. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  73. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  74. EP260507a: COLIBRÍ optical observations
  75. EP260507a: NOT optical observations
  76. EP260507a: further Liverpool Telescope observations
  77. EP260507a: Liverpool Telescope optical upper limits
  78. EP260507a: TRT optical counterpart detection
  79. EP260507a: Kinder optical counterpart candidate
  80. EP260507a: LCO optical counterpart
  81. EP260507a: Einstein Probe detection of an X-ray transient
  82. GRB 260504B: SVOM/ECLAIRs refined analysis
  83. EP260502a is likely a flaring star
  84. GRB 260503A: GECAM-B observation of a burst
  85. GRB 260421B: radio observation with the VLA
  86. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  87. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  88. GRB 260430B: AstroSat CZTI detection of a long burst
  89. GRB 260502A: SVOM/GRM observation of a short GRB
  90. GRB 260503A: SVOM/GRM observation of a GRB
  91. GRB 260504B: REM optical/NIR observations
  92. GRB 260504B: LCO z-band upper limit
  93. SVOM GRB 260504B: MASTER-OAFA optical observations
  94. GRB 260504B: SVOM detection of a short burst
  95. GRB 260504A: Fermi GBM Final Real-time Localization
  96. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  97. EP260502a: Einstein Probe detection of an X-ray transient
  98. GRB 260429A: SVOM/GRM observation of a short burst
  99. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  100. EP260430a: refined analysis of the EP-WXT and follow-up 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