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"

37198 results found.

  1. GRB 251125B: Fermi GBM Final Real-time Localization
  2. Fermi GRB 251125A: Global MASTER-Net observations report
  3. GRB 251125A: Fermi GBM Final Real-time Localization
  4. GRB 251124A: Fermi GBM Localization by automated pipeline
  5. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  6. EP251124a: Optical upper limit with Kinder observations
  7. GRB 251122B: Fermi GBM Final Localization
  8. Fermi GRB 251124a: Global MASTER-Net observations report
  9. GRB 251124a: Fermi GBM Final Localization
  10. GRB 251116C: Swift-XRT confirmation of fading
  11. GRB 251122A/EP251122a: FTW optical and NIR observations
  12. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  13. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  14. GRB 251122A / EP251122a: EP-FXT counterpart detection
  15. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  16. GRB 251122A / EP251122a: WFST optical observations
  17. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  18. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  19. GRB 251122A / EP251122a: LCO optical upper limits
  20. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  21. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  22. GRB 251122A / EP251122a: SVOM detection of a long burst
  23. EP251118a: Continued Optical Detection with Kinder observations
  24. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  25. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  26. EP251118a: Xinglong-2.16m optical observation
  27. GRB 251115A: Fermi GBM Observation
  28. GRB 251121A: Fermi GBM Final Real-time Localization
  29. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  30. GRB 251118A: Swift/UVOT Detection
  31. EP251118a / GRB 251118C: SAO RAS optical observations
  32. GRB 251118A: Glowbug gamma-ray detection
  33. GRB 251118A: Fermi GBM Observation
  34. GRB 251118A: Swift-XRT afterglow detection
  35. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  36. EP251118a: Optical detection with Kinder observations
  37. GRB 251118A: GECAM-B detection
  38. EP251118a / GRB 251118C: SVOM/VT optical observation
  39. GRB 251118A: NuSTAR detection of bright prompt emission
  40. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  41. GRB 251116C: NOT optical observations
  42. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  43. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  44. GRB 251018A: FRAM-Auger optical detection
  45. GRB 251117A: Swift-XRT observations
  46. EP251118A / GRB 251118C : MASTER optical counterpart observations
  47. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  48. Konus-Wind detection of GRB 251118C (EP251118a)
  49. GRB 251117A: Insight-HXMT/HE detection
  50. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  51. GRB 251116D: SVOM/GRM observation of a long GRB
  52. EP251118a: GOTO optical afterglow detection
  53. GRB 251119A: SVOM detection of a possible burst
  54. EP251118a: NOT spectroscopic redshift of z = 1.216
  55. GRB 251118A: Fermi-LAT detection
  56. EP251118a: NOT candidate optical counterpart
  57. GRB 251118A: Swift ToO observations
  58. Fermi GRB 251118B: Global MASTER-Net observations report
  59. GRB 251118B: Fermi GBM Final Real-time Localization
  60. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  61. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  62. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  63. GRB 251118A: Fermi GBM Final Real-time Localization
  64. GRB 251116C: SVOM/ECLAIRs refined analysis
  65. GRB 251116B: SVOM/ECLAIRs refined analysis
  66. GRB 251117A: AstroSat CZTI detection
  67. GRB 251114B: Insight-HXMT/HE detection
  68. GRB 251114B: GECAM-B detection of a short burst
  69. GRB 251117A: Fermi GBM observation
  70. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  71. GRB 251116D: Insight-HXMT/HE detection
  72. GRB 251115A: Swift-XRT observations
  73. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  74. GRB 251117A: SVOM/GRM observation of a short burst
  75. GRB 251117A: Tiled Swift observations
  76. GRB 251117A: Fermi-LAT detection
  77. GRB 251116C: Swift/BAT arcminute localization of a burst
  78. GRB 251116B: SVOM/VT optical upper limit
  79. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  80. GRB 251116C: Swift-XRT observations
  81. GRB 251117A: Fermi GBM Final Localization Correction
  82. GRB 251116D: Glowbug gamma-ray detection
  83. EP251023a: Assy AZT-20 optical observations
  84. EP251023a: UAFO and AbAO optical observations
  85. GRB 251116D: AstroSat CZTI detection
  86. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  87. GRB 251116C: SVOM/VT optical upper limit
  88. GRB 251025B: further Mondy optical observations
  89. GRB 251111A: Mondy optical upper limit
  90. GRB 251116B: EP-FXT follow-up observation
  91. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  92. GRB 251116B: LCO optical upper limits
  93. GRB 251116C: LCO optical upper limits
  94. GRB 251116C: SVOM detection of a burst
  95. GRB 251116B: SVOM detection of a burst
  96. GRB 251116A: Fermi GBM Final Real-time Localization
  97. GRB 251115A: Tiled Swift observations
  98. GRB 251115A: Fermi-LAT detection
  99. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  100. Fermi GRB 251115A: Global MASTER-Net observations report

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