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"

45621 results found.

  1. GRB 251126A: Swift detection of a burst
  2. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  3. EP251124b follow-up observation by EP-FXT
  4. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  5. EP251124b: NOT r- and z-band optical upper limits
  6. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  7. Fermi GRB 251125B: Global MASTER-Net observations report
  8. GRB 251125B: Fermi GBM Final Real-time Localization
  9. EP251124b: Global MASTER-Net observations report
  10. EP251124b: EP-WXT detection of a fast X-ray transient
  11. EP251124a: Xinglong GWAC-F60A optical observation
  12. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  13. Fermi GRB 251125A: Global MASTER-Net observations report
  14. GRB 251125A: Fermi GBM Final Real-time Localization
  15. EP251124a: NOT r- and z-band optical upper limits
  16. EP251124a: Global MASTER-Net observations report
  17. EP251124a: Swift-XRT observations
  18. GRB 251124A: Fermi GBM Localization by automated pipeline
  19. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  20. EP251124a: Optical upper limit with Kinder observations
  21. GRB 251122B: Fermi GBM Final Localization
  22. EP251118A: 6 GHz VLA Detection
  23. Fermi GRB 251124a: Global MASTER-Net observations report
  24. GRB 251124a: Fermi GBM Final Localization
  25. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  26. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  27. EP251124a: GROWTH-India Telescope optical upper limits
  28. EP251124a: Einstein Probe detection of an X-ray transient
  29. GRB 251116C: Swift-XRT confirmation of fading
  30. GRB 251122A/EP251122a: FTW optical and NIR observations
  31. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  32. The EP-WXT trigger 01709248783 is likely a flaring star
  33. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  34. EP251118A: 3.6m DOT optical afterglow detection
  35. GRB 251122A / EP251122a: EP-FXT counterpart detection
  36. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  37. GRB 251122A / EP251122a: WFST optical observations
  38. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  39. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  40. GRB 251122A / EP251122a: LCO optical upper limits
  41. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  42. EP251122a: Global MASTER-Net observations report
  43. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  44. GRB 251122A / EP251122a: SVOM detection of a long burst
  45. EP251122a: Einstein Probe detection of an X-ray transient
  46. EP251118a: Continued Optical Detection with Kinder observations
  47. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  48. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  49. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  50. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  51. EP251118a: Xinglong-2.16m optical observation
  52. GRB 251115A: Fermi GBM Observation
  53. The EP-WXT trigger 01709248635 is likely a flaring star
  54. GRB 251121A: Fermi GBM Final Real-time Localization
  55. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  56. Fermi trigger No 785388351: Global MASTER-Net observations report
  57. EP251118A: 1.3m DFOT optical afterglow detection
  58. GRB 251118A: Swift/UVOT Detection
  59. EP251118a / GRB 251118C: SAO RAS optical observations
  60. GRB 251118A: Glowbug gamma-ray detection
  61. GRB 251118A: Fermi GBM Observation
  62. GRB 251118A: Swift-XRT afterglow detection
  63. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  64. EP251118a: Optical detection with Kinder observations
  65. GRB 251118A: GECAM-B detection
  66. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  67. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  68. EP251118a / GRB 251118C: SVOM/VT optical observation
  69. The EP-WXT trigger 01709248403 is likely a flaring star
  70. GRB 251118A: NuSTAR detection of bright prompt emission
  71. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  72. GRB 251116C: NOT optical observations
  73. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  74. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  75. GRB 251018A: FRAM-Auger optical detection
  76. GRB 251117A: Swift-XRT observations
  77. EP251118A / GRB 251118C : MASTER optical counterpart observations
  78. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  79. Konus-Wind detection of GRB 251118C (EP251118a)
  80. The EP-WXT trigger 01709248388 is likely a flaring star
  81. EP251118a: FTW optical and NIR observations
  82. GRB 251117A: Insight-HXMT/HE detection
  83. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  84. EP251118a: VLT near-infrared observation
  85. GRB 251116D: SVOM/GRM observation of a long GRB
  86. EP251118a: GOTO optical afterglow detection
  87. GRB 251119A: SVOM detection of a possible burst
  88. EP251118a: NOT spectroscopic redshift of z = 1.216
  89. EP251118a: Global MASTER-Net observations report
  90. EP251118a: preliminary result of EP-FXT follow-up observation
  91. LAT GRB251118.86: Global MASTER-Net observations report
  92. GRB 251118A: Fermi-LAT detection
  93. EP251118a: NOT candidate optical counterpart
  94. GRB 251118A: Swift ToO observations
  95. EP251118a: Einstein Probe detected of a fast X-ray transient
  96. Fermi GRB 251118B: Global MASTER-Net observations report
  97. GRB 251118B: Fermi GBM Final Real-time Localization
  98. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  99. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  100. GRB 251117A: FTW Observations of Swift candidate X-ray sources

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