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"
  1. Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
  2. Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
  3. Swift GRB 241010A: Global MASTER-Net observations report
  4. Fermi trigger No 750291012: Global MASTER-Net observations report
  5. GRB 241010A: J-band observations with WINTER
  6. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  7. Fermi GRB 241010B: Global MASTER-Net observations report
  8. GRB 241010B: Fermi GBM Final Real-time Localization
  9. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 241010A: Enhanced Swift-XRT position
  11. GRB 241010A: LCO optical observations
  12. GRB 241010A: Swift detection of a burst with an optical counterpart
  13. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  14. GRB 241006A: Swift-BAT refined analysis
  15. GRB 241009A: Swift ToO observations
  16. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  17. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  18. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  19. GRB 241008A: Fermi GBM Observation
  20. GRB 241008A: Fermi-LAT detection
  21. GRB 241002B: Swift-XRT afterglow detection
  22. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  23. GRB 241002A: NOT optical upper limits
  24. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  25. Fermi GRB 241008A: Global MASTER-Net observations report
  26. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  27. GRB 241008A: Fermi GBM Final Real-time Localization
  28. IceCube-241006A: No candidates from the Zwicky Transient Facility
  29. GRB 241006A: GRANDMA optical upper limits
  30. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  31. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  32. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  33. GRB 240910A: LBT optical observations
  34. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  35. GRB 241006A: Swift-XRT refined Analysis
  36. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  37. GRB 241006A: PRIME near-infrared upper limits
  38. GRB 241006A: Swift/UVOT Upper Limits
  39. GRB 241006A: SVOM/VT follow-up and optical upper limit
  40. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  41. IceCube Alert 241006.94: Global MASTER-Net observations report
  42. GRB 241001A: Swift-XRT afterglow detection
  43. GRB 241006A: Enhanced Swift-XRT position
  44. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 241006A: Swift detection of a burst
  46. Swift GRB241006.91: Global MASTER-Net observations report
  47. GRB 240930B: SVOM/C-GFT optical upper limit
  48. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  50. Fermi trigger No 749721670: Global MASTER-Net observations report
  51. GRB 241004A: SVOM/GRM observation
  52. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  53. GRB 240930B / EP 240930a: SVOM/GRM observation
  54. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  55. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  56. GRB 241002B: Fermi GBM Observation
  57. Fermi trigger No 749735279: Global MASTER-Net observations report
  58. Fermi trigger No 749630753: Global MASTER-Net observations report
  59. Fermi trigger No 749693019: Global MASTER-Net observations report
  60. GRB 241002B: Swift-XRT observations
  61. GRB 241002C: SVOM/C-GFT optical upper limit
  62. GRB 241002A: Swift-BAT refined analysis
  63. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  64. GRB 241002B: Swift ToO observations
  65. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  66. Konus-Wind detection of GRB 240926A
  67. GRB 241002B: PRIME near-infrared detection
  68. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  69. GRB 241002C: Swift ToO observations
  70. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  71. IPN triangulation of GRB 240930B / EP 240930a
  72. GRB 241001A : SVOM/VT optical detection
  73. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  74. GRB 241002D: SVOM/GRM observation
  75. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  76. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  77. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  78. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  79. GRB 241002C : MITSuME Akeno optical upper limits
  80. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  81. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  82. GRB241001A: REM optical/NIR upper limits
  83. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  84. GRB 241002A: Swift/UVOT Upper Limits
  85. EP240930a: Liverpool Telescope observations
  86. GRB 241002A: Swift-XRT refined Analysis
  87. GRB 241002A: LCOGT Optical Upper Limits
  88. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  89. GRB 241001A: Swift/UVOT Detection
  90. GRB 241001A: VLT/X-shooter redshift
  91. GRB 241002B: GOTO optical counterpart candidate
  92. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  93. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  94. GRB 241001A: correction to GCN 37667
  95. GRB 240929A: Liverpool Telescope prompt followup observations
  96. Fermi GRB 241002B: Global MASTER-Net observations report
  97. GRB 241001A: Swift-XRT observations
  98. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  99. GRB 241002B: Fermi GBM Final Real-time Localization
  100. GRB241001A: optical afterglow candidate

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