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"

32720 results found.

  1. GRB 260321A: EP-FXT follow-up observation
  2. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  3. EP260321a: GOTO detection of blue variable source
  4. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  5. EP260321a: further Kinder optical observations
  6. GRB 260321A: SVOM/VT optical upper limits
  7. EP260321a: Las Cumbres upper limit
  8. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  9. GRB 260320A: Insight-HXMT/HE detection
  10. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  11. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  12. EP260321a: SVOM/VT optical upper limit
  13. GRB 260310A: continued optical observation at Mondy
  14. Fermi GBM Sub-Threshold Detection of GRB 260321A
  15. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  16. EP260321a: Global MASTER-Net observations report
  17. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  18. GRB 260318A: Glowbug gamma-ray detection
  19. GRB 260310A / AT 2026fgk: KAIT optical observations
  20. GRB 260320A: NuSTAR detection of prompt emission
  21. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  22. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  23. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  24. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  25. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  26. GRB 260310A/AT2026fgk: LBT near-infrared observations
  27. NOEMA Detection of GRB 260310A / AT 2026fgk
  28. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  29. GRB 260318A: SVOM/GRM observation
  30. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  31. GRB 260318A: GECAM-B observation
  32. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  33. Fermi GRB 260318A: Global MASTER-Net observations report
  34. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  35. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  36. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  37. GRB 260310A / AT 2026fgk: radio detection with the VLA
  38. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  39. GRB 260310A / AT2026fgk: LCO optical observations
  40. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  41. GRB 260316B: GECAM-B observation
  42. GRB 260316B: SVOM/GRM observation
  43. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  44. EP260316a: COLIBRÍ faint optical counterpart candidate
  45. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  46. GRB 260316B: AstroSat CZTI detection
  47. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  48. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  49. EP260316a: Xinglong optical upper limit
  50. EP260316a: optical upper limit with Kinder observations
  51. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  52. GRB 260314A: Glowbug gamma-ray detection
  53. IceCube-260315A: COLIBRÍ optical observations
  54. EP260314a: Xinglong optical upper limit
  55. EP260314a: optical upper limit with Kinder observations
  56. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  57. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  58. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  59. GRB 260310A / AT 2026fgk: iTelescope optical observations
  60. EP260314a: COLIBRÍ optical upper limit
  61. GRID detection of GRB 260312B
  62. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  63. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  64. EP260314a: Global MASTER-Net observations report
  65. EP260314a: SVOM/VT optical candidate
  66. GRB 260314A: GECAM-B observation of a burst
  67. GRB 260310A / AT2026fgk: SAO RAS optical observations
  68. GRB 260310A/AT2026fgk: radio detection at 15GHz
  69. GRB 260310A / AT2026fgk: TNG NIR detection
  70. GRB 260310A / AT2026fgk: OASDG optical observations
  71. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  72. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  73. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  74. Fermi GRB 260314A: Global MASTER-Net observations report
  75. Fermi GRB 260313A: Global MASTER-Net observations report
  76. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  77. GRB 260313A: A Correction to the Fermi GBM Final Localization
  78. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  79. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  80. GRB 260310B: Insight-HXMT/HE detection
  81. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  82. GRB 260310A: NOT optical polarimetry
  83. GRB 260312B: AstroSat CZTI detection
  84. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  85. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  86. GRB 260308A: Insight-HXMT/HE detection
  87. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  89. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  90. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  91. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  92. GRB260310A / AT2026fgk: P200 Spectroscopy
  93. GRB 260312B: Glowbug gamma-ray detection
  94. GRB 260310A: Fermi GBM Observation
  95. GRB 260310A: potential optical counterpart
  96. Fermi GRB 260312B: Global MASTER-Net observations report
  97. Fermi GRB 260311B: Global MASTER-Net observations report
  98. GRB 260310B: GECAM-B observation of a burst
  99. Retraction of GCN 43965: GRB is actually solar flare
  100. GRB 260131A/B: radio detection with the VLA

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