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"

28235 results found.

  1. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  2. GRB 260415B: Glowbug gamma-ray detection
  3. GRB 260411B: Glowbug gamma-ray detection
  4. EP260416a: COLIBRÍ optical counterpart candidate
  5. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  6. EP260416a: Global MASTER-Net observations report
  7. EP260416a: Einstein Probe detection of an X-ray transient
  8. GOTO26djh/AT2026jpw : MASTER OT observation
  9. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  10. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  11. GRB 260415B: NuSTAR detection of long prompt emission
  12. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  13. Fermi trigger No 797912738: Global MASTER-Net observations report
  14. GRB 260414A: Glowbug gamma-ray detection
  15. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  16. EP260321a: CMO SAI J,K observations
  17. Fermi GRB 260413A: Global MASTER-Net observations report
  18. GRB 260410A: Glowbug gamma-ray detection of a short burst
  19. Fermi GRB 260412A: Global MASTER-Net observations report
  20. GRB 260412A: Fermi GBM Observation
  21. GRB 260411B: Fermi-LAT detection
  22. GRB 260411B: COLIBRÍ optical observations
  23. GRB 260410B: Fermi GBM Observation
  24. GRB260411B: 3.6m DOT optical observation
  25. GRB 260411A: SVOM/GRM observation
  26. GRB 260411B: SVOM/GRM observation of a long burst
  27. GRB 260409A: Insight-HXMT/HE detection
  28. GRB 260411B: Fermi GBM Detection
  29. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  30. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  31. GRB 260410A: COLIBRÍ optical upper limit
  32. EP-WXT01709259790: Optical Upper limits with kinder observations
  33. GRB 260410A: Fermi GBM Observation
  34. GRB 260410B: SVOM/GRM detection of a short faint burst
  35. EP-WXT01709259790: Xinglong optical upper limit
  36. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  37. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  38. EP260409a: COLIBRÍ optical upper limits
  39. EP260409a: Global MASTER-Net observations report
  40. EP260409a: Einstein Probe detection of an X-ray transient
  41. EP260321a: VLA radio detection
  42. GRB 260407A: Glowbug gamma-ray detection
  43. GRB 260402A: SVOM/ECLAIRs refined analysis
  44. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  45. EP260402a / GRB 260402A: Mephisto optical upper limits
  46. EP-WXT01709259586: Xinglong optical upper limit
  47. EP260403a: Mephisto optical upper limits
  48. EP260402a/GRB 260402A: Xinglong optical upper limit
  49. EP260405a: GMOS-N optical upper limits
  50. EP260405a: Global MASTER-Net observations report
  51. EP260405a: Einstein Probe detection of a fast X-ray transient
  52. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  53. Fermi trigger No 797039833: Global MASTER-Net observations report
  54. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  55. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  56. The EP-WXT trigger 01709259586 is likely a flaring star
  57. GRB 260330B: SVOM/VT further optical observation
  58. EP260403a: LCO optical observations of the counterpart
  59. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  60. EP260403a: LCO optical counterpart detection
  61. EP260403a: COLIBRÍ optical counterpart candidate
  62. GRB 260330B: SVOM/VT optical candidate
  63. EP260403a: Einstein Probe detection of an X-ray transient
  64. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  65. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  66. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  67. GRB 260402C: NuSTAR detection of prompt emission
  68. GRB 260402C: AstroSat CZTI detection of a long burst
  69. EP260324A / AT 2026hir: COLIBRÍ optical observations
  70. GRB 260402A: WINTER J-band upper limit
  71. GRB260402A: GROWTH-India Telescope optical upper limit
  72. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  73. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  74. GRB 260401A: SVOM/GRM observation
  75. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  76. GRB 260402A: Kilonova-Catcher optical upper limit
  77. GRB 260402A: MASTER optical observations
  78. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  80. GRB 260402A: SVOM detection of a burst
  81. Fermi GRB 260401A: Global MASTER-Net observations report
  82. GRB 260401A: Fermi GBM Observation
  83. GRB 260401A: NuSTAR detection of prompt emission
  84. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  85. GRB 260401A: MAXI/GSC detection
  86. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  87. GRB 260401A: Fermi GBM Final Real-time Localization
  88. EP260329b: Mondy and Assy-Turgen optical upper limits
  89. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  90. EP260321a :Xinglong optical observations
  91. EP260327a: Xinglong optical upper limit
  92. GRB 260330B: SVOM/VT optical upper limits
  93. Konus-Wind detection of GRB 260320A
  94. GRB 260321A: SVOM/ECLAIRs refined analysis
  95. EP260329b: J-band upper limits with WINTER
  96. EP260329a: J-band upper limit with WINTER
  97. GRB 260330A: Glowbug gamma-ray detection
  98. Fermi GBM Sub-Threshold Detection of GRB 260330B
  99. GRB 260330B: LCO optical upper limits
  100. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope

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