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"

19692 results found.

  1. GRB 261026A: KAIT optical observations
  2. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  3. GRB 261026A: SVOM detection of a burst
  4. EP261025a: J-band upper limit with WINTER
  5. EP261023a: J-band upper limit with WINTER
  6. EP 261025a: COLIBRÍ optical upper limit
  7. EP261025a: Einstein Probe detection of a fast X-ray transient
  8. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  9. EP261015a: VST optical observations
  10. EP261023a: Mondy optical upper limit
  11. EP261015a: MAO/AZT-22 optical observations
  12. EP261015a: VLA non-detection
  13. EP261023a: NOT optical counterpart candidate
  14. EP261023a: Einstein Probe detection of an X-ray transient
  15. EP261015a: GSP multiband optical follow-up observations
  16. GRB 261017A: SVOM/GRM observation
  17. EP261015a: Further optical observations with the 1.3m DFOT
  18. GRB 261020B: AstroSat CZTI detection of a short burst
  19. EP261015a: AZT-20 Assy-Turgen optical observations
  20. GRB 261017A: SAO RAS optical upper limit
  21. EP261015a: Follow-up with the 1.3m DFOT
  22. EP261015a: Terskol Zeiss-2000 optical upper limit
  23. EP261007b: Further EP-FXT follow-up observations
  24. GRB 261017A: COLIBRÍ optical upper limit
  25. EP261015a: COLIBRÍ optical observations of a rebrightening
  26. GRB 261017A: Possible Swift/UVOT Detection
  27. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  28. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  29. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  30. EP261015b: NOT Optical Observations
  31. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  32. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  33. GRB 261017A : MITSuME Akeno optical upper limits
  34. GRB 261017A: Nanshan/NEXT optical upper limit
  35. GRB 261017A: Enhanced Swift-XRT position
  36. GRB 261017A: Swift detection of a burst
  37. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  38. EP261015b: Refined analysis of EP-FXT observations
  39. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  40. EP261015a: refined analysis of EP-FXT observations
  41. EP261015c: J-band upper limit with WINTER
  42. EP261015a: J-band upper limit with WINTER
  43. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  44. GRB 261011A: 1.3m DFOT optical upper limit
  45. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  46. EP261015a: SVOM/VT optical observation
  47. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  48. EP261015a: COLIBRÍ optical observations
  49. EP261015c: Einstein Probe detection of a fast X-ray transient
  50. EP261015b: Einstein Probe detection of an X-ray transient
  51. EP261015a: Einstein Probe detection of a fast X-ray transient
  52. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  53. GRB 261010A: LBT tentative near-infrared detection
  54. GRB 261011A: SAO RAS and AbAO optical observations
  55. GRB 261008A: SVOM/GRM observation
  56. EP261006a : MeerKAT radio observations.
  57. GRID detection of GRB 261010A
  58. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  59. GRB 261011A: Swift-XRT refined Analysis
  60. GRB 261011A: Enhanced Swift-XRT position
  61. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  62. MAXI GRB261012.23: Global MASTER-Net observations report
  63. GRB 261011A: REM optical/NIR observations
  64. Konus-Wind detection of GRB 261007A/EP261007a
  65. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  66. EP261006a: 10 GHz VLA observations
  67. GRB 261011A: VLT/X-shooter redshift constraints
  68. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  69. GRB 261011A: Optical followup from Sichuan South Observatory
  70. GRB 261011A: GMG Optical Observation
  71. GRB 261011A: Liverpool Telescope optical observations
  72. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  73. GRB 261011A: GROWTH-India Telescope optical observations
  74. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  75. GRB 261011A: Optical follow-up observations with Kinder
  76. GRB 261011A: SVOM/C-GFT optical observations
  77. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  78. GRB 261011A: LCO optical observations
  79. GRB 261011A: LCO optical observations
  80. GRB 261011A: TRT optical afterglow detection
  81. GRB 261011A: Swift detection of an unusual burst
  82. GRB 261011A: SVOM detection of a long bright burst
  83. GRB 261010A: Enhanced Swift-XRT position
  84. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  86. GRB 261010A: Swift detection of a burst
  87. EP261006a: Kilonova-Catcher optical follow-up and detection
  88. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  89. EP261010a: SVOM/VT optical upper limits
  90. EP261006a: Liverpool Telescope optical follow-up
  91. EP261010a: NOT optical upper limits
  92. EP261010a Einstein Probe detection of an X-ray transient
  93. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  94. EP261007b: SVOM/ECLAIRs Upper Limit
  95. EP261006a: Optical follow-up observations with MATCH
  96. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  97. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  98. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  99. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  100. GRB 261008A: Fermi GBM Final Real-time Localization

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