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"

36160 results found.

  1. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  2. GRB 251126A: further SAO RAS optical observations
  3. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  4. GRB 251126A NUTTelA-TAO Early Measurements
  5. GRB251126A: MAO/AZT-22 optical observations
  6. GRB 251128A: Fermi GBM Final Real-time Localization
  7. GRB251126A: Continued optical observation from 1.3m DFOT
  8. GRB 251126A: Swift/UVOT Detection
  9. GRB 251126A: Mondy and SAO RAS optical observations
  10. GRB 251126A: Swift-XRT refined Analysis
  11. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  12. GRB 251126A: NOT optical observations
  13. GRB 251126A: 1.3m DFOT optical afterglow detection
  14. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  15. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  16. GRB 251125B: GECAM-B detection
  17. Fermi GRB 251127A: Global MASTER-Net observations report
  18. GRB 251127A: Fermi GBM Final Real-time Localization
  19. GRB 251126A: Enhanced Swift-XRT position
  20. GRB 251126A: Kilonova-Catcher optical afterglow detection
  21. GRB 251126A: Asiago i-band detection
  22. GRB 251126A: Nanshan/HMT optical afterglow detection
  23. Swift GRB 251126A: Global MASTER-Net observations report
  24. GRB 251121A: Fermi GBM Observation
  25. GRB 251126A: Prompt enhanced Swift-XRT position
  26. GRB 251126A: GIT discovery of the likely optical afterglow
  27. GRB 251126A: Swift detection of a burst
  28. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  29. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  30. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  31. Fermi GRB 251125B: Global MASTER-Net observations report
  32. GRB 251125B: Fermi GBM Final Real-time Localization
  33. Fermi GRB 251125A: Global MASTER-Net observations report
  34. GRB 251125A: Fermi GBM Final Real-time Localization
  35. GRB 251124A: Fermi GBM Localization by automated pipeline
  36. GRB 251122B: Fermi GBM Final Localization
  37. Fermi GRB 251124a: Global MASTER-Net observations report
  38. GRB 251124a: Fermi GBM Final Localization
  39. GRB 251116C: Swift-XRT confirmation of fading
  40. GRB 251122A/EP251122a: FTW optical and NIR observations
  41. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  42. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  43. GRB 251122A / EP251122a: EP-FXT counterpart detection
  44. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  45. GRB 251122A / EP251122a: WFST optical observations
  46. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  47. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  48. GRB 251122A / EP251122a: LCO optical upper limits
  49. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  50. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  51. GRB 251122A / EP251122a: SVOM detection of a long burst
  52. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  53. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  54. EP251118a: Xinglong-2.16m optical observation
  55. GRB 251115A: Fermi GBM Observation
  56. GRB 251121A: Fermi GBM Final Real-time Localization
  57. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  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. GRB 251118A: GECAM-B detection
  65. EP251118a / GRB 251118C: SVOM/VT optical observation
  66. GRB 251118A: NuSTAR detection of bright prompt emission
  67. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  68. GRB 251116C: NOT optical observations
  69. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  70. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  71. GRB 251018A: FRAM-Auger optical detection
  72. GRB 251117A: Swift-XRT observations
  73. EP251118A / GRB 251118C : MASTER optical counterpart observations
  74. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  75. Konus-Wind detection of GRB 251118C (EP251118a)
  76. GRB 251117A: Insight-HXMT/HE detection
  77. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  78. GRB 251116D: SVOM/GRM observation of a long GRB
  79. GRB 251119A: SVOM detection of a possible burst
  80. EP251118a: NOT spectroscopic redshift of z = 1.216
  81. GRB 251118A: Fermi-LAT detection
  82. GRB 251118A: Swift ToO observations
  83. Fermi GRB 251118B: Global MASTER-Net observations report
  84. GRB 251118B: Fermi GBM Final Real-time Localization
  85. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  86. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  87. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  88. GRB 251118A: Fermi GBM Final Real-time Localization
  89. GRB 251116C: SVOM/ECLAIRs refined analysis
  90. GRB 251116B: SVOM/ECLAIRs refined analysis
  91. GRB 251117A: AstroSat CZTI detection
  92. GRB 251114B: Insight-HXMT/HE detection
  93. GRB 251114B: GECAM-B detection of a short burst
  94. GRB 251117A: Fermi GBM observation
  95. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  96. GRB 251116D: Insight-HXMT/HE detection
  97. GRB 251115A: Swift-XRT observations
  98. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  99. GRB 251117A: SVOM/GRM observation of a short burst
  100. GRB 251117A: Tiled Swift observations

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