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"

32688 results found.

  1. EP260321a :Xinglong optical observations
  2. EP260327a: Xinglong optical upper limit
  3. EP260329b: GOTO detection of optical counterpart
  4. GRB 260330B: SVOM/VT optical upper limits
  5. Konus-Wind detection of GRB 260320A
  6. Konus-Wind detection of GRB 260316B (duplicate submission)
  7. Konus-Wind detection of GRB 260316B
  8. GRB 260321A: SVOM/ECLAIRs refined analysis
  9. EP260329b: J-band upper limits with WINTER
  10. EP260329a: J-band upper limit with WINTER
  11. GRB 260330A: Glowbug gamma-ray detection
  12. GRB 260310A: VLA Multi-frequency Radio Observations
  13. Fermi GBM Sub-Threshold Detection of GRB 260330B
  14. GRB 260330B: LCO optical upper limits
  15. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  16. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  17. EP260329a: COLIBRÍ optical upper limit
  18. EP260329a: EP-FXT follow up observation
  19. EP260329a: NOT optical counterpart candidate
  20. EP260329b: Global MASTER-Net observations report
  21. GRB 260327A: Insight-HXMT/HE detection
  22. EP260329b: Optical follow-up with Kinder observations
  23. EP 260329b: COLIBRÍ optical observations
  24. EP260329a: Optical upper limit with Kinder observations
  25. EP260329b: LCO optical observations of the counterpart
  26. GRB 260326A: Insight-HXMT/HE detection
  27. EP260329b: Einstein Probe detection of an X-ray transient
  28. EP-WXT trigger 01709259209: TRT optical counterpart detection
  29. GRID detection of GRB 260326A
  30. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  31. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  32. EP260327a: SVOM/VT optical upper limits
  33. SMA Detection of GRB 260310A / AT 2026fgk
  34. GRB 260307B: ATCA Radio Upper Limits
  35. EP260327a: WINTER J-band upper limit
  36. EP260327a: COLIBRÍ optical upper limits
  37. EP260327a: Gemini-North optical upper limits
  38. EP260324a: GROWTH-India Telescope optical observation
  39. EP260327a: Global MASTER-Net observations report
  40. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  41. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  42. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  43. IPN triangulation of GRB 260320A
  44. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  45. GRB 260326A: Fermi GBM Detection
  46. EP260321a: JinShan near-infrared observations
  47. EP260321a: Upper limits from a neutrino search with IceCube
  48. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  49. IPN triangulation of GRB 260316B
  50. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  51. GRID detection of GRB 260320A
  52. EP260321a: Gemini-South confirmation of a supernova (duplicate submission)
  53. EP260321a: Gemini-South confirmation of a supernova
  54. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  55. GRB 260310A: LBT optical observations
  56. EP260321A: Mondy optical observations
  57. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  58. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  59. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  60. Fermi GRB 260323A: Global MASTER-Net observations report
  61. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  62. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  63. GRB 260320A: Glowbug gamma-ray detection
  64. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  65. EP260321a: COLIBRÍ further optical observations and brightening
  66. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  67. EP260214b: ATCA 6 GHz detection
  68. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  69. GRB 260321A: EP-FXT follow-up observation
  70. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  71. EP260321a: GOTO detection of blue variable source
  72. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  73. EP260321a: further Kinder optical observations
  74. GRB 260321A: SVOM/VT optical upper limits
  75. EP260321a: Las Cumbres upper limit
  76. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. GRB 260320A: Insight-HXMT/HE detection
  78. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  79. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  80. EP260321a: SVOM/VT optical upper limit
  81. GRB 260310A: continued optical observation at Mondy
  82. Fermi GBM Sub-Threshold Detection of GRB 260321A
  83. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  84. EP260321a: Global MASTER-Net observations report
  85. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  86. GRB 260318A: Glowbug gamma-ray detection
  87. GRB 260310A / AT 2026fgk: KAIT optical observations
  88. GRB 260320A: NuSTAR detection of prompt emission
  89. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  90. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  91. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  92. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  93. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  94. GRB 260310A/AT2026fgk: LBT near-infrared observations
  95. NOEMA Detection of GRB 260310A / AT 2026fgk
  96. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  97. GRB 260318A: SVOM/GRM observation
  98. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  99. GRB 260318A: GECAM-B observation
  100. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT

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