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"

28100 results found.

  1. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  2. GRB 260320A: Glowbug gamma-ray detection
  3. EP260321a: COLIBRÍ further optical observations and brightening
  4. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  5. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  6. GRB 260321A: EP-FXT follow-up observation
  7. EP260321a: GOTO detection of blue variable source
  8. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  9. EP260321a: further Kinder optical observations
  10. GRB 260321A: SVOM/VT optical upper limits
  11. EP260321a: Las Cumbres upper limit
  12. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  14. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  15. EP260321a: SVOM/VT optical upper limit
  16. Fermi GBM Sub-Threshold Detection of GRB 260321A
  17. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  18. EP260321a: Global MASTER-Net observations report
  19. EP260321a: Einstein Probe detection of an X-ray transient
  20. GRB 260318A: Glowbug gamma-ray detection
  21. GRB 260310A / AT 2026fgk: KAIT optical observations
  22. GRB 260320A: NuSTAR detection of prompt emission
  23. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  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. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  27. GRB 260318A: SVOM/GRM observation
  28. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  29. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  30. Fermi GRB 260318A: Global MASTER-Net observations report
  31. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  32. GRB 260310A / AT 2026fgk: radio detection with the VLA
  33. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  34. GRB 260310A / AT2026fgk: LCO optical observations
  35. GRB 260316B: SVOM/GRM observation
  36. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  37. EP260316a: COLIBRÍ faint optical counterpart candidate
  38. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  39. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  40. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  41. EP260316a: Xinglong optical upper limit
  42. EP260316a: optical upper limit with Kinder observations
  43. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  44. GRB 260314A: Glowbug gamma-ray detection
  45. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  46. IceCube-260315A: COLIBRÍ optical observations
  47. EP260314a: Xinglong optical upper limit
  48. EP260314a: optical upper limit with Kinder observations
  49. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  50. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  51. GRB 260310A / AT 2026fgk: iTelescope optical observations
  52. EP260314a: COLIBRÍ optical upper limit
  53. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP260314a: Global MASTER-Net observations report
  55. EP260314a: SVOM/VT optical candidate
  56. Fermi trigger No 795185313: Global MASTER-Net observations report
  57. IceCube Alert 260315A: Global MASTER-Net observations report
  58. EP260314a: Einstein Probe detection of an X-ray transient
  59. GRB 260310A / AT2026fgk: SAO RAS optical observations
  60. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  61. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  62. Fermi GRB 260314A: Global MASTER-Net observations report
  63. Fermi GRB 260313A: Global MASTER-Net observations report
  64. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  65. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  66. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  67. GRB 260312B: AstroSat CZTI detection
  68. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  69. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  70. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  71. GRB 260312B: Glowbug gamma-ray detection
  72. GRB 260310A: Fermi GBM Observation
  73. GRB 260310A: potential optical counterpart
  74. Fermi GRB 260312B: Global MASTER-Net observations report
  75. Fermi GRB 260311B: Global MASTER-Net observations report
  76. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  77. GRB 260131A/B: radio detection with the VLA
  78. EP260302a: MeerKAT radio counterpart
  79. GRB 260308A: SVOM/GRM observation of a short GRB
  80. EP260306a: Mondy optical upper limit
  81. Fermi GRB 260310B: Global MASTER-Net observations report
  82. Fermi GRB 260310A: Global MASTER-Net observations report
  83. GRB 260208A: radio detection with the VLA
  84. GRB 260307A: Glowbug gamma-ray detection
  85. Fermi GBM Sub-Threshold Detection of GRB 260307B
  86. GRB 260307B: Mephisto optical upper limits
  87. GRB 260307B: possible NOT optical counterpart
  88. GRB 260307B: SVOM/VT upper limit with X band data analysis
  89. Fermi GRB 260307A: Global MASTER-Net observations report
  90. GRB260307B: GROWTH-India Telescope optical upper limit
  91. GRB 260307B: SVOM/VT optical candidate
  92. GRB 260307B: SVOM/C-GFT upper limit
  93. GRB 260307B: SVOM detection of a burst
  94. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  95. GRB 260207A: TESS Detection and Possible VLA Counterpart
  96. EP260302a: SVOM/VT optical observation
  97. EP260306a: Gemini-North redshift z = 4.773
  98. EP260306a: SVOM/VT optical observation
  99. EP260302a: Gemini-South redshift z = 1.535
  100. EP260306a: COLIBRÍ optical observations of the fading and red counterpart

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