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"

46042 results found.

  1. GRB 250128B: Swift-XRT refined Analysis
  2. GRB 250128B: Fermi GBM Observation
  3. GRB 250128B: GOTO optical upper limit
  4. Swift GRB 250128B: Global MASTER-Net observations report
  5. EP250125a: Upper limits from Swift/BAT-GUANO
  6. GRB 250128B: LCO optical observations
  7. GRB 250128B: Swift detection of a short burst
  8. GRB 250128B: Fermi GBM Final Real-time Localization
  9. GRB 250127A: Swift-XRT observations
  10. GRB 250127B: DDOTI Upper Limit on the Afterglow
  11. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  12. GRB 250127A: EP-FXT afterglow detection
  13. Fermi GRB 250128A: Global MASTER-Net observations report
  14. GRB 250128A: Fermi GBM Final Real-time Localization
  15. GRB 250117A: Fermi GBM Observation
  16. Fermi GRB 250127B: Global MASTER-Net observations report
  17. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  18. GRB 250127A: SVOM/VT upper limit
  19. GRB 250127B: Fermi GBM Final Real-time Localization
  20. IPN triangulation of GRB 250119C
  21. GRB 250127A: Swift ToO observations
  22. GRB 250127A: LCO optical upper limit
  23. GRB 241223A: cubesat Avion detection
  24. GRB 250127A: SVOM detection of a long burst
  25. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  26. EP250125A: Non-detection from Fermi-GBM Observations
  27. GRB 250126A: MAXI/GSC detection
  28. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  29. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  30. GRB 250126A: Fermi GBM Final Real-time Localization
  31. GECAM-A detection of a bright burst from SGR 1E1841-045
  32. GRB 250118A: Fermi GBM Observation
  33. EP250125a: Optical upper limit with Kinder observations
  34. EP250125a: REM optical counterpart detection
  35. GRB 250119C: Fermi GBM Observation
  36. EP250125a: Swift/XRT detection of a fading counterpart
  37. EP250125a: a new X-ray transient detected by Einstein Probe
  38. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  39. The EP-WXT trigger 01709130758 is a false trigger
  40. The EP-WXT trigger 01709130758 is a false trigger
  41. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  42. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  43. IPN triangulation of a bright burst from SGR 1E1841-045
  44. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  45. EP250108a: AbAO, CMO and Terskol optical upper limits
  46. Konus-Wind detection of GRB 250118B
  47. GRB 250121A: Fermi GBM Observation
  48. IPN triangulation of GRB 250118B
  49. Konus-Wind detection of GRB 250119B
  50. IPN triangulation of GRB 250119B
  51. GRB 250122A: Fermi GBM Final Real-time Localization
  52. Improved IPN triangulation of GRB 250107C
  53. GRB 250114A: Swift-BAT refined analysis
  54. GRB 250121A: INTEGRAL/SPI-ACS detection
  55. GRB 250121A: Fermi-LAT detection
  56. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  57. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  58. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  59. GRB 250121A: Fermi GBM Final Real-time Localization
  60. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  61. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  62. GRB 250119B: Fermi GBM Observation
  63. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  64. Konus-Wind detection of GRB 250117A
  65. IPN triangulation of GRB 250117A (short)
  66. ATCA detection of possible radio counterpart to GRB 250114A
  67. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  68. GRB 250119B: INTEGRAL/SPI-ACS detection
  69. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  70. EP 250108A: Late-time optical observation by LCO
  71. GRB 250117A: SVOM/GRM observation of a short burst
  72. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  73. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  74. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  75. GRB 250119C: Fermi GBM Final Real-time Localization
  76. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  77. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  78. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  79. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  81. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  82. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  83. GRB 250117A: GECAM observation of a short burst
  84. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  85. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  86. GRB 250119B: Fermi GBM Final Real-time Localization
  87. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  88. GRB 250119A: Fermi GBM Final Real-time Localization
  89. GRB 250118A: Fermi GBM Final Real-time Localization
  90. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  92. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  93. EP250108a / AT2025kg: GMG Optical Observations
  94. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  95. EP250108a / AT2025kg: VLA radio upper limit
  96. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  97. Konus-Wind detection of GRB 250116A
  98. GRB 250116A: GECAM-B detection of a long burst
  99. GRB 241217A / EP241217B: radio detection with the VLA
  100. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT 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