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"

21823 results found.

  1. GRB 260504B: SVOM detection of a short burst
  2. Fermi GRB 260504A: Global MASTER-Net observations report
  3. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  4. EP260502a: Einstein Probe detection of an X-ray transient
  5. GRB 260429A: SVOM/GRM observation of a short burst
  6. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  7. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  8. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  9. EP260429a: LCO optical upper limits
  10. EP260430a: LCO optical upper limits
  11. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  12. EP260430a: Einstein Probe detection of an X-ray transient
  13. EP260429a: EP-WXT detection of a fast X-ray transient
  14. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  15. EP260416a: Mondy and Terskol optical upper limits
  16. GRB 260424B: COLIBRÍ optical upper limit
  17. Konus-Wind detection of GRB 260424B
  18. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  19. GRB 260401A: cubesat Avion detection
  20. EP260321a: Upper limits from ATCA radio observations
  21. GRB 260421B: Kilonova-Catcher optical afterglow detection
  22. EP260416a: Mondy optical observations
  23. GRB 260421B: SVOM/ECLAIRs refined analysis
  24. GRB 260421B: 3.6m DOT optical observation
  25. EP260416a: ZTSh R band observations
  26. GRB 260421B: SVOM/GRM observation
  27. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  28. GOTO26djh/AT2026jpw: ATCA radio detection
  29. GRB 260421B: J-band upper limit with WINTER
  30. GRB 260421B: LCO optical counterpart detection
  31. GOTO26djh/AT2026jpw: radio detection at 15GHz
  32. GRB 260421B: SVOM/VT optical observations
  33. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  34. GRB 260310A: Late-time Chandra X-ray Detection
  35. EP260416a: 1.3m DFOT optical observation
  36. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  37. GRB 260421B: LCO optical afterglow confirmation
  38. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  39. GRB 260421B: TRT optical counterpart detection
  40. GRB 260421B: SVOM detection of a long burst
  41. EP260321a: VLA radio follow-up
  42. GRB 260412A: LCOGT Optical Upper Limits
  43. EP260416a: Optical follow-up observations with Kinder
  44. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  45. GRB 260417A: SVOM/GRM observation
  46. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  47. EP260417a: GROWTH-India Telescope optical upper limit
  48. EP260417b: GROWTH-India Telescope optical upper limit
  49. EP260416a: Ondrejov D50 optical detection
  50. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  51. EP260416a: GMG Optical Observation
  52. Konus-Wind detection of GRB 260411B
  53. EP260416a: LCO observations confirm end of flaring phase
  54. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  55. EP260417a: TRT optical counterpart detection
  56. EP260417a: Einstein Probe detection of an X-ray transient
  57. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  58. EP260417b: Einstein Probe detection of a fast X-ray transient
  59. EP260416a: KAIT optical upper limit
  60. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  61. EP260416a: WFST optical observations and rebrightening
  62. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  63. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  64. EP260416a: COLIBRÍ optical counterpart candidate
  65. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  66. EP260416a: Einstein Probe detection of an X-ray transient
  67. GOTO26djh/AT2026jpw : MASTER OT observation
  68. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  69. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  70. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  71. EP260321a: CMO SAI J,K observations
  72. Konus-Wind detection of GRB 260410A (short/hard)
  73. GRB 260411B: Fermi-LAT detection
  74. GRB 260412A: SVOM detection of a long burst
  75. GRB 260411B: COLIBRÍ optical observations
  76. GRB260411B: 3.6m DOT optical observation
  77. GRB 260411A: SVOM/GRM observation
  78. GRB 260411B: SVOM/GRM observation of a long burst
  79. GRB 260411B: GOTO optical counterpart candidate
  80. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  81. GRB 260410A: COLIBRÍ optical upper limit
  82. EP-WXT01709259790: Optical Upper limits with kinder observations
  83. EP-WXT01709259790: Xinglong optical upper limit
  84. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  86. EP260409a: COLIBRÍ optical upper limits
  87. EP260409a: Einstein Probe detection of an X-ray transient
  88. EP260321a: VLA radio detection
  89. GRB 260402A: SVOM/ECLAIRs refined analysis
  90. EP260402a / GRB 260402A: Mephisto optical upper limits
  91. EP-WXT01709259586: Xinglong optical upper limit
  92. EP260403a: Mephisto optical upper limits
  93. EP260402a/GRB 260402A: Xinglong optical upper limit
  94. EP260321a: uGMRT observations
  95. EP260405a: GMOS-N optical upper limits
  96. EP260405a: Einstein Probe detection of a fast X-ray transient
  97. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  98. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  99. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  100. GRB 260330B: SVOM/VT further optical observation

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