Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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. GRB 231115A: archival HST observations
  2. Integral GRB231115.65: Global MASTER-Net observations report
  3. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  4. GRB 231115A: Swift ToO observations
  5. Fermi GRB 231115A: Global MASTER-Net observations report
  6. GRB 231115A: significance of INTEGRAL localization alignment with M82
  7. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  8. GRB 231115A position consistent with M 82 galaxy
  9. GRB 231115A: Fermi GBM Final Real-time Localization
  10. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  11. GRB 231111A: Swift-BAT refined analysis
  12. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  13. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  14. Fermi GRB 231114A: Global MASTER-Net observations report
  15. GRB 231113A (short): Glowbug gamma-ray detection
  16. GRB 231114A (short): Glowbug gamma-ray detection
  17. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  18. GECAM-B observation of a short burst from SGR J1555-5402
  19. GRB 231114A: Fermi GBM Final Localization
  20. LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
  21. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  22. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  23. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  24. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  25. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  26. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  27. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  28. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  29. GRB 231110A: Swift-BAT refined analysis
  30. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  31. GRB 231106A: Glowbug gamma-ray detection
  32. GRB 231111A: Xinglong-2.16m optical observations
  33. GRB 231110A: Swift-UVOT Upper Limits
  34. LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
  35. GRB 231111A: Afterglow redshift from OSIRIS+/GTC
  36. GRB 231104A: VZLUSAT-2 detection
  37. GRB 231111A: TNG tentative redshift
  38. GRB 231110A: Glowbug gamma-ray detection
  39. GRB 231110A: AstroSat CZTI detection
  40. GRB 231111A NUTTelA-TAO / BSTI Early Measurements
  41. GRB 231111A: Leavitt Observatory optical observations
  42. GRB231111A: Optical follow-up observations with Mephisto
  43. GRB 231111A: GMG observation (correction)
  44. LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
  45. GRB 231111A: GMG observation upper limit
  46. GRB 231106B: GRBAlpha detection
  47. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  48. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  49. GRB 231111A: Swift-XRT refined Analysis
  50. GRB 231111A: Mondy optical observations
  51. GRB 231111A: GECAM-C detection of a long burst (correction)
  52. GRB 231110A: GECAM-B detection (correction)
  53. GRB 231111A: Enhanced Swift-XRT position
  54. GRB 231111A: GECAM-C detection of a long burst
  55. GRB 231110A: GECAM detection
  56. GRB 231110A: GOTO optical upper limits
  57. GRB 231110A: SAO RAS optical observations
  58. GRB 231110A: Swift-XRT afterglow detection
  59. GRB231111A: YAHPT Observations
  60. GRB231111A: GIT confirmation of the optical afterglow
  61. GRB 231111A: MASTER OT earlier detection
  62. GRB 231111A: Nanshan/HMT optical observations
  63. GRB 231111A: Swift detection of a burst with an optical counterpart
  64. Swift GRB231111.60: Global MASTER-Net observations report
  65. GRB231110A: WFST Observation and upper limits
  66. Swift GRB231110.89: Global MASTER-Net observations report
  67. GRB 231110A: Swift detection of a burst
  68. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  69. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  70. GRB 231109A: Fermi GBM Final Localization
  71. IceCube-231103A: No candidates from the Zwicky Transient Facility
  72. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  73. Fermi trigger No 721204446: Global MASTER-Net observations report
  74. Fermi GRB 231108A: Global MASTER-Net observations report
  75. GRB 231108A: Fermi GBM Final Real-time Localization
  76. LIGO/Virgo/KAGRA O4 Landscape
  77. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  78. GRB 231106A: AstroSat CZTI detection
  79. GRB 231106A: CALET Gamma-Ray Burst Monitor detection
  80. GRB 231104A: Swift-BAT refined analysis
  81. Fermi trigger No 721006392: Global MASTER-Net observations report
  82. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  83. GRB 231104A: FRAM-ORM optical limit
  84. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  85. Fermi GRB 231106A: Global MASTER-Net observations report
  86. GRB 231104A: Wendelstein Optical/Infrared Observations
  87. GRB 231104A: NuSTAR Observation of the prompt emission
  88. GRB 231106A: Fermi GBM Final Real-time Localization
  89. GRB 231104A: 3.6m DOT optical upper limit
  90. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  91. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  92. Fermi-LAT gamma-ray observations of IceCube-231103A
  93. GRB 231104A: NOT upper limit
  94. GRB 231104A: Fermi GBM Observation
  95. GRB 231104B: Fermi GBM Final Real-time Localization
  96. Fermi GRB 231103A: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  98. GRB 231104A: AKO Upper Limit
  99. GRB 231104A: AstroSat CZTI detection
  100. GRB 231104A: Swift-XRT refined Analysis

Advanced

Download all Circulars as a .tar.gz archive:
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