Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. 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"

38679 results found.

  1. GRB 251129A: Swift ToO observations
  2. GRB 251129A / EP251129a: SVOM/VT optical fading
  3. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  4. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  5. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  6. GRB 251128A: Fermi GBM Observation
  7. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  8. GRB 251129A: SVOM detection of a burst
  9. SVOM GRB251129A: Global MASTER-Net observations report
  10. GRB 251129A: SVOM detection of a burst
  11. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  12. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  13. GRB 251127A: Glowbug gamma-ray detection
  14. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  15. GRB 251126A: further SAO RAS optical observations
  16. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  17. GRB 251126A NUTTelA-TAO Early Measurements
  18. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  19. GRB251126A: MAO/AZT-22 optical observations
  20. GRB 251128A: Fermi GBM Final Real-time Localization
  21. GRB251126A: Continued optical observation from 1.3m DFOT
  22. GRB 251126A: Swift/UVOT Detection
  23. EP251124a: Pan-STARRS ri-band imaging and photometry
  24. GRB 251126A: Mondy and SAO RAS optical observations
  25. GRB 251126A: Swift-XRT refined Analysis
  26. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  27. GRB 251126A: NOT optical observations
  28. GRB 251126A: 1.3m DFOT optical afterglow detection
  29. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  30. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  31. GRB 251125B: GECAM-B detection
  32. GRB 251127A: Fermi GBM Final Real-time Localization
  33. GRB 251126A: Enhanced Swift-XRT position
  34. GRB 251126A: Kilonova-Catcher optical afterglow detection
  35. GRB 251126A: Asiago i-band detection
  36. GRB 251126A: Nanshan/HMT optical afterglow detection
  37. GRB 251121A: Fermi GBM Observation
  38. GRB 251126A: Prompt enhanced Swift-XRT position
  39. GRB 251126A: GIT discovery of the likely optical afterglow
  40. GRB 251126A: Swift detection of a burst
  41. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  42. EP251124b follow-up observation by EP-FXT
  43. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  44. EP251124b: NOT r- and z-band optical upper limits
  45. GRB 251125B: Fermi GBM Final Real-time Localization
  46. EP251124b: EP-WXT detection of a fast X-ray transient
  47. EP251124a: Xinglong GWAC-F60A optical observation
  48. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  49. GRB 251125A: Fermi GBM Final Real-time Localization
  50. EP251124a: NOT r- and z-band optical upper limits
  51. EP251124a: Swift-XRT observations
  52. GRB 251124A: Fermi GBM Localization by automated pipeline
  53. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  54. EP251124a: Optical upper limit with Kinder observations
  55. GRB 251122B: Fermi GBM Final Localization
  56. EP251118A: 6 GHz VLA Detection
  57. GRB 251124a: Fermi GBM Final Localization
  58. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  59. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  60. EP251124a: GROWTH-India Telescope optical upper limits
  61. EP251124a: Einstein Probe detection of an X-ray transient
  62. GRB 251116C: Swift-XRT confirmation of fading
  63. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  64. The EP-WXT trigger 01709248783 is likely a flaring star
  65. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  66. EP251118A: 3.6m DOT optical afterglow detection
  67. GRB 251122A / EP251122a: EP-FXT counterpart detection
  68. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  69. GRB 251122A / EP251122a: WFST optical observations
  70. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  71. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  72. GRB 251122A / EP251122a: LCO optical upper limits
  73. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  74. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  75. GRB 251122A / EP251122a: SVOM detection of a long burst
  76. EP251122a: Einstein Probe detection of an X-ray transient
  77. EP251118a: Continued Optical Detection with Kinder observations
  78. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  79. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  80. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  81. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  82. EP251118a: Xinglong-2.16m optical observation
  83. GRB 251115A: Fermi GBM Observation
  84. The EP-WXT trigger 01709248635 is likely a flaring star
  85. GRB 251121A: Fermi GBM Final Real-time Localization
  86. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  87. EP251118A: 1.3m DFOT optical afterglow detection
  88. GRB 251118A: Swift/UVOT Detection
  89. EP251118a / GRB 251118C: SAO RAS optical observations
  90. GRB 251118A: Glowbug gamma-ray detection
  91. GRB 251118A: Fermi GBM Observation
  92. GRB 251118A: Swift-XRT afterglow detection
  93. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  94. EP251118a: Optical detection with Kinder observations
  95. GRB 251118A: GECAM-B detection
  96. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  97. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  98. EP251118a / GRB 251118C: SVOM/VT optical observation
  99. The EP-WXT trigger 01709248403 is likely a flaring star
  100. GRB 251118A: NuSTAR detection of bright prompt emission

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