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"

23569 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. NuSTAR 261020, a 830s hard X-ray transient
  16. EP261015a: GSP multiband optical follow-up observations
  17. GRB 261017A: SVOM/GRM observation
  18. EP261015a: Further optical observations with the 1.3m DFOT
  19. EP261015a: AZT-20 Assy-Turgen optical observations
  20. GRB 261017A: SAO RAS optical upper limit
  21. GRB 260903A
  22. EP261015a: Follow-up with the 1.3m DFOT
  23. EP261015a: Terskol Zeiss-2000 optical upper limit
  24. EP261007b: Further EP-FXT follow-up observations
  25. GRB 261017A: COLIBRÍ optical upper limit
  26. EP261015a: COLIBRÍ optical observations of a rebrightening
  27. Konus-Wind detection of GRB 261017A
  28. GRB 261017A: Possible Swift/UVOT Detection
  29. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  30. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  31. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  32. EP261015b: NOT Optical Observations
  33. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  34. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  35. GRB 261017A : MITSuME Akeno optical upper limits
  36. GRB 261017A: Nanshan/NEXT optical upper limit
  37. GRB 261017A: Enhanced Swift-XRT position
  38. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  39. GRB 261017A: Swift detection of a burst
  40. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  41. EP261015b: Refined analysis of EP-FXT observations
  42. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  43. EP261015a: refined analysis of EP-FXT observations
  44. EP261015c: J-band upper limit with WINTER
  45. EP261015a: J-band upper limit with WINTER
  46. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  47. GRB 261011A: 1.3m DFOT optical upper limit
  48. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  49. EP261015a: SVOM/VT optical observation
  50. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  51. GRB 261010A: VLA radio observations
  52. EP261015a: COLIBRÍ optical observations
  53. EP261015c: Einstein Probe detection of a fast X-ray transient
  54. EP261015b: Einstein Probe detection of an X-ray transient
  55. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  56. EP261015a: Einstein Probe detection of a fast X-ray transient
  57. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  58. GRB 261010A: ASKAP non-detection of a radio afterglow
  59. GRB 261010A: LBT tentative near-infrared detection
  60. GRB 261011A: SAO RAS and AbAO optical observations
  61. GRB 261010A: Glowbug gamma-ray detection
  62. GRB 261008A: SVOM/GRM observation
  63. EP261006a : MeerKAT radio observations.
  64. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  65. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  66. GRB 261010A: Swift-XRT refined Analysis
  67. GRB 261011A: Swift-XRT refined Analysis
  68. GRB 261011A: Enhanced Swift-XRT position
  69. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  70. GRB 261011A: REM optical/NIR observations
  71. Konus-Wind detection of GRB 261010A
  72. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  73. EP261006a: 10 GHz VLA observations
  74. GRB 261011A: VLT/X-shooter redshift constraints
  75. GRB 261010A: Swift-BAT refined analysis
  76. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  77. GRB 261011A: Optical followup from Sichuan South Observatory
  78. GRB 261011A: GMG Optical Observation
  79. GRB 261011A: Liverpool Telescope optical observations
  80. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  81. GRB 261011A: GROWTH-India Telescope optical observations
  82. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  83. GRB 261011A: Optical follow-up observations with Kinder
  84. GRB 261011A: SVOM/C-GFT optical observations
  85. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  86. GRB 261011A: LCO optical observations
  87. GRB 261011A: LCO optical observations
  88. GRB 261011A: TRT optical afterglow detection
  89. GRB 261011A: Swift detection of an unusual burst
  90. GRB 261011A: SVOM detection of a long bright burst
  91. GRB 261010A: Enhanced Swift-XRT position
  92. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  93. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  94. GRB 261010A: Swift detection of a burst
  95. EP261006a: Kilonova-Catcher optical follow-up and detection
  96. GRB 261001A: SVOM/GRM observation
  97. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  98. EP261010a: SVOM/VT optical upper limits
  99. EP261006a: Liverpool Telescope optical follow-up
  100. EP261010a: NOT 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