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"

28203 results found.

  1. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  2. GRB 261017A : MITSuME Akeno optical upper limits
  3. GRB 261017A: Swift-XRT refined Analysis
  4. GRB 261017A: Nanshan/NEXT optical upper limit
  5. GRB 261017A: Enhanced Swift-XRT position
  6. GRB 261017A: Fermi GBM Observation
  7. GRB 261017A: Swift detection of a burst
  8. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  9. EP261015b: Refined analysis of EP-FXT observations
  10. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  11. EP261015a: refined analysis of EP-FXT observations
  12. EP261015c: J-band upper limit with WINTER
  13. EP261015a: J-band upper limit with WINTER
  14. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  15. GRB 261011A: 1.3m DFOT optical upper limit
  16. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  17. EP261015a: SVOM/VT optical observation
  18. GRB 261010A: VLA radio observations
  19. EP261015a: COLIBRÍ optical observations
  20. EP261015c: Einstein Probe detection of a fast X-ray transient
  21. EP261015b: Einstein Probe detection of an X-ray transient
  22. EP261015a: Einstein Probe detection of a fast X-ray transient
  23. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  24. GRB 261010A: LBT tentative near-infrared detection
  25. GRB 261011A: SAO RAS and AbAO optical observations
  26. GRB 261010A: Glowbug gamma-ray detection
  27. GRB 261008A: SVOM/GRM observation
  28. GRB 261009A: GECAM-B detection of a burst
  29. EP261006a : MeerKAT radio observations.
  30. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  32. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  33. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  34. GRB 261010A: Swift-XRT refined Analysis
  35. GRB 261011A: Swift-XRT refined Analysis
  36. GRB 261011A: Enhanced Swift-XRT position
  37. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  38. GRB 261011A: Swift-BAT refined analysis
  39. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  40. MAXI GRB261012.23: Global MASTER-Net observations report
  41. GRB 261011A: REM optical/NIR observations
  42. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  43. EP261006a: 10 GHz VLA observations
  44. GRB 261011A: VLT/X-shooter redshift constraints
  45. GRB 261012A: MAXI GSC detection
  46. GRB 261010A: Swift-BAT refined analysis
  47. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  48. GRB 261011A: Optical followup from Sichuan South Observatory
  49. GRB 261011A: GMG Optical Observation
  50. GRB 261011A: Liverpool Telescope optical observations
  51. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  52. GRB 261010A: NOT confirmation of the optical afterglow
  53. GRB 261010A: Fermi GBM Observation
  54. GRB 261011A: continued LCO optical observations
  55. EP261007b: Global MASTER-Net observations report
  56. GRB 261011A: GROWTH-India Telescope optical observations
  57. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  58. Swift GRB 261011A: Global MASTER-Net observations report
  59. GRB 261011A: Optical follow-up observations with Kinder
  60. GRB 261011A: SVOM/C-GFT optical observations
  61. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  62. GRB 261011A: LCO optical observations
  63. GRB 261011A: SVOM/VT optical observation from VHF data
  64. GRB 261011A: LCO optical observations
  65. GRB 261011A: TRT optical afterglow detection
  66. GRB 261011A: Swift detection of an unusual burst
  67. GRB 261011A: SVOM detection of a long bright burst
  68. GRB 261010A: Enhanced Swift-XRT position
  69. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  70. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  71. GRB 261010A: Swift detection of a burst
  72. EP261006a: Kilonova-Catcher optical follow-up and detection
  73. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  74. EP261010a: SVOM/VT optical upper limits
  75. EP261006a: Liverpool Telescope optical follow-up
  76. EP261010a: NOT optical upper limits
  77. EP261010a: Global MASTER-Net observations report
  78. EP261010a Einstein Probe detection of an X-ray transient
  79. GRB261007A: Lesedi optical afterglow detection
  80. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  81. EP261007b: SVOM/ECLAIRs Upper Limit
  82. EP261006a: Optical follow-up observations with MATCH
  83. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  84. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. GRB 261007A: SVOM/ECLAIRs refined analysis
  86. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  87. GRB 261007A: Glowbug gamma-ray detection
  88. EP261007b: NOT optical observations, variable source outside the FXT region
  89. EP261007b: SVOM/C-GFT optical upper limits
  90. EP261007b: J-band upper limit with WINTER
  91. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  92. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  93. EP261007a/GRB 261007A：Xinglong optical observation
  94. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  95. EP261006a: Optical follow-up observations with Kinder
  96. EP261006a: Liverpool Telescope optical observations
  97. EP261006a: Early Optical Observations by WFST
  98. GRB 261007A / EP261007a: SVOM/VT optical observations
  99. GRB 261007A: Swift-XRT afterglow detection
  100. EP261007b: SVOM/VT optical upper limits

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