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"

19689 results found.

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