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"

19205 results found.

  1. NuSTAR 261020, a 830s hard X-ray transient
  2. EP261015a: GSP multiband optical follow-up observations
  3. GRB 261017A: SVOM/GRM observation
  4. GRB 261021A: Fermi GBM Final Real-time Localization
  5. EP261015a: Further optical observations with the 1.3m DFOT
  6. GRB 261020B: AstroSat CZTI detection of a short burst
  7. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  8. EP261015a: AZT-20 Assy-Turgen optical observations
  9. GRB 261020A: Fermi GBM Observation
  10. GRB 261017A: SAO RAS optical upper limit
  11. EP261015a: Wendelstein 43 cm optical observations
  12. GRB 260903A
  13. EP261015a: Follow-up with the 1.3m DFOT
  14. EP261015a: Terskol Zeiss-2000 optical upper limit
  15. EP261007b: Further EP-FXT follow-up observations
  16. GRB 261017A: COLIBRÍ optical upper limit
  17. GRB 261020A: MAXI GSC detection
  18. GRB 261020A: Fermi GBM Final Real-time Localization
  19. EP261015a: COLIBRÍ optical observations of a rebrightening
  20. GRB 261019A: Fermi GBM Final Localization
  21. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  22. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  23. GRB 261017A: Swift-BAT refined analysis
  24. GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
  25. EP261015b: NOT Optical Observations
  26. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  27. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  28. GRB 261017A : MITSuME Akeno optical upper limits
  29. GRB 261017A: Swift-XRT refined Analysis
  30. GRB 261017A: Nanshan/NEXT optical upper limit
  31. GRB 261017A: Fermi GBM Observation
  32. GRB 261017A: Fermi GBM Final Real-time Localization
  33. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  34. EP261015b: Refined analysis of EP-FXT observations
  35. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  36. EP261015a: refined analysis of EP-FXT observations
  37. EP261015c: J-band upper limit with WINTER
  38. EP261015a: J-band upper limit with WINTER
  39. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  40. GRB 261011A: 1.3m DFOT optical upper limit
  41. EP261015a: SVOM/VT optical observation
  42. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  43. GRB 261010A: VLA radio observations
  44. EP261015a: COLIBRÍ optical observations
  45. EP261015c: Einstein Probe detection of a fast X-ray transient
  46. EP261015b: Einstein Probe detection of an X-ray transient
  47. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  48. EP261015a: Einstein Probe detection of a fast X-ray transient
  49. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  50. The EP-WXT trigger 01709321333 is likely a flaring star
  51. GRB 261010A: ASKAP non-detection of a radio afterglow
  52. GRB 261010A: LBT tentative near-infrared detection
  53. GRB 261011A: SAO RAS and AbAO optical observations
  54. GRB 261010A: Glowbug gamma-ray detection
  55. GRB 261008A: SVOM/GRM observation
  56. GRB 261009A: GECAM-B detection of a burst
  57. EP261006a : MeerKAT radio observations.
  58. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  60. GRB 261013A: Fermi GBM Final Real-time Localization
  61. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  62. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  63. GRID detection of GRB 261010A
  64. GRB 261011A: GECAM-B observation
  65. GRB 261011B: GECAM-B observation
  66. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  67. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  68. GRB 261010A: Swift-XRT refined Analysis
  69. GRB 261011A: Swift-XRT refined Analysis
  70. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  71. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  72. GRB 261011A: Swift-BAT refined analysis
  73. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  74. MAXI GRB261012.23: Global MASTER-Net observations report
  75. GRB 261011A: REM optical/NIR observations
  76. Konus-Wind detection of GRB 261011A
  77. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  78. EP261006a: 10 GHz VLA observations
  79. GRB 261012A: MAXI GSC detection
  80. GRB 261010A: Swift-BAT refined analysis
  81. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  82. GRB 261011A: Optical followup from Sichuan South Observatory
  83. GRB 261011A: GMG Optical Observation
  84. GRB 261011A: Liverpool Telescope optical observations
  85. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  86. GRB 261010A: NOT confirmation of the optical afterglow
  87. GRB 261010A: Fermi GBM Observation
  88. GRB 261011B: Fermi GBM Final Localization
  89. GRB 261011A: continued LCO optical observations
  90. EP261007b: Global MASTER-Net observations report
  91. GRB 261011A: GROWTH-India Telescope optical observations
  92. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  93. Swift GRB 261011A: Global MASTER-Net observations report
  94. GRB 261011A: Optical follow-up observations with Kinder
  95. GRB 261011A: SVOM/C-GFT optical observations
  96. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  97. GRB 261011A: LCO optical observations
  98. GRB 261011A: SVOM/VT optical observation from VHF data
  99. GRB 261011A: LCO optical observations
  100. GRB 261011A: GOTO optical counterpart detection

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