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"
  1. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  2. The EP-WXT trigger 01709130758 is a false trigger
  3. The EP-WXT trigger 01709130758 is a false trigger
  4. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  5. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  6. IPN triangulation of a bright burst from SGR 1E1841-045
  7. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  8. EP250108a: AbAO, CMO and Terskol optical upper limits
  9. Konus-Wind detection of GRB 250118B
  10. GRB 250121A: Fermi GBM Observation
  11. IPN triangulation of GRB 250118B
  12. Konus-Wind detection of GRB 250119B
  13. IPN triangulation of GRB 250119B
  14. GRB 250122A: Fermi GBM Final Real-time Localization
  15. Improved IPN triangulation of GRB 250107C
  16. GRB 250114A: Swift-BAT refined analysis
  17. GRB 250121A: INTEGRAL/SPI-ACS detection
  18. GRB 250121A: Fermi-LAT detection
  19. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  20. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  21. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  22. GRB 250121A: Fermi GBM Final Real-time Localization
  23. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  24. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  25. GRB 250119B: Fermi GBM Observation
  26. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  27. Konus-Wind detection of GRB 250117A
  28. IPN triangulation of GRB 250117A (short)
  29. ATCA detection of possible radio counterpart to GRB 250114A
  30. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  31. GRB 250119B: INTEGRAL/SPI-ACS detection
  32. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  33. EP 250108A: Late-time optical observation by LCO
  34. GRB 250117A: SVOM/GRM observation of a short burst
  35. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  36. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  38. GRB 250119C: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  40. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  41. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  42. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  44. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  45. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  46. GRB 250117A: GECAM observation of a short burst
  47. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  48. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  49. GRB 250119B: Fermi GBM Final Real-time Localization
  50. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  51. GRB 250119A: Fermi GBM Final Real-time Localization
  52. GRB 250118A: Fermi GBM Final Real-time Localization
  53. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  55. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  56. EP250108a / AT2025kg: GMG Optical Observations
  57. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  58. EP250108a / AT2025kg: VLA radio upper limit
  59. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  60. Konus-Wind detection of GRB 250116A
  61. GRB 250116A: GECAM-B detection of a long burst
  62. GRB 241217A / EP241217B: radio detection with the VLA
  63. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  64. Swift Trigger 1282245 is not a GRB
  65. GRB 250116A: Fermi-LAT detection
  66. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  67. GRB 250114B: Swift-XRT afterglow detection
  68. GRB 250114B: SVOM/VT upper limit
  69. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  70. EP250108a: MeerKAT radio upper limit
  71. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  72. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  73. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  74. Konus-Wind detection of GRB 250113A
  75. IPN triangulation of GRB 250113A
  76. GRB 250114B: Liverpool Telescope optical upper limit
  77. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  78. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  79. GRB 250114B: Swift-XRT observations
  80. GRB 250114A: LCO optical counterpart detection.
  81. GRB 250114B: OHP/T193 optical upper limit
  82. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  83. GRB 250114A: Swift-XRT refined Analysis
  84. Integral GRB250114.55: Global MASTER-Net observations report
  85. GRB 250114A: LCOGT optical afterglow i-band detection
  86. GRB 250114B : GIT optical upper limit
  87. GRB 250114B: Swift ToO observations
  88. EP250111a: SAO RAS optical upper limit
  89. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  90. GRB 250114B: a short GRB detected with INTEGRAL
  91. EP250108a: correction to GCN 38908
  92. GRB 250114A: Enhanced Swift-XRT position
  93. GRB 250113A: INTEGRAL/SPI-ACS detection
  94. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  95. GRB 250114A: REM detection of the optical and NIR counterpart
  96. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  97. Swift GRB250114A: Global MASTER-Net OT detection
  98. GRB 250114A: LCO optical observations
  99. GRB 250114A: TRT optical observations
  100. Swift GRB 250114A: 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