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. LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
  2. GRB 231120A: Fermi GBM Final Real-time Localization
  3. GRB 231117A: Swift-XRT refined Analysis
  4. GRB 231118A: Swift-XRT refined Analysis
  5. GRB 231118A: MeerLICHT afterglow detection
  6. LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
  7. GRB 231117A: OHP/T120 optical observations
  8. GRB 231118A: VLT/X-shooter redshift
  9. Fermi trigger No 722039659: Global MASTER-Net observations report
  10. GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading
  11. LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
  12. GRB 231117A: MAAO 0.7-m telescope optical upper limit
  13. GRB 231117A: AKO Follow-Up Observation
  14. GRB 231117A: GECAM-C detection
  15. GRB 231118A: AstroSat CZTI detection
  16. GRB 231115A: Upper limit from CALET Gamma-Ray Burst Monitor
  17. GRB 231117A: 10 GHz VLA detection
  18. GRB 231118A: Las Cumbres optical detection
  19. GRB 231118B: BALROG localization (Fermi Trigger 722039659 / GRB 231118940)
  20. GRB 231118B: Fermi GBM Final Real-time Localization
  21. GRB 231118A: LCOGT Optical Observations
  22. GRB 231118A: MASTER OT observation
  23. GRB 231118A: Continued Skynet Observations
  24. Swift GRB231118.72: Global MASTER-Net observations report
  25. GRB 231118A: Enhanced Swift-XRT position
  26. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  27. GRB 231118A: Swift-XRT position
  28. GRB 231118A: Skynet Optical Afterglow Discovery
  29. GRB 231117A: SOAR/Goodman imaging of the afterglow
  30. GRB 231118A: Swift detection of a burst
  31. GRB 231118A: Fermi GBM Final Real-time Localization
  32. GRB 231117A: Lowell Discovery Telescope Observations
  33. GRB 231117A: ePESSTO+ host galaxy redshift confirmation
  34. GRB 231117A: ATCA detection of a radio counterpart
  35. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  36. GRB 231117A: GRBAlpha detection
  37. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  38. GRB 231117A: Keck spectroscopy of afterglow candidate
  39. GRB 231115A: Wendelstein Optical/Infrared Observations
  40. GRB 231115A: JinShan optical upper limits
  41. LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
  42. GRB 231117A: GIT optical follow-up
  43. GRB 231117A: LT observations consistent with fading
  44. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  45. GRB 231117A: REM optical and NIR early-time observations
  46. GRB231117A: AGILE/MCAL analysis
  47. GRB 231117A: AKO Optical Upper Limit
  48. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  49. Swift GRB 231117A: Global MASTER-Net observations report
  50. GRB 231117A (short): Glowbug gamma-ray detection
  51. GRB 231117A: ATLAS non-detection of an optical counterpart
  52. Konus-Wind detection of GRB 231117A (short/hard)
  53. GRB 231115A : OHP/T120 optical upper limit
  54. GRB 231115A: optical observations from INAF observatories
  55. GRB 231117A : MITSuME Akeno optical upper limits
  56. GRB 231117A: AGILE detection of a bright short burst
  57. GRB 231117A: Enhanced Swift-XRT position
  58. GRB 231117A: GOTO optical upper limits
  59. GRB 231117A: AstroSat CZTI detection of a bright short burst
  60. GRB 231117A: Swift detection of a bright short burst
  61. GRB 231115A: Non-detection of radio emission with CHIME/FRB
  62. GRB 231111A: Swift/UVOT Detection
  63. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  64. GRB231115A: Liverpool Telescope imaging
  65. GRB 231115A: NuSTAR Follow-Up Observations
  66. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  67. GRB 231115A: Swift-XRT and Swift-UVOT observations
  68. Fermi GRB 231116A: Global MASTER-Net observations report
  69. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  70. GRB 231115A: AGILE/MCAL upper limits
  71. GRB 231115A: Insight-HXMT/HE detection
  72. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  73. GRB 231116A: Fermi GBM Final Real-time Localization
  74. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  75. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  76. GRB 231115A / AT2023xvj: Updated GIT analysis
  77. GRB 231115A: archival Chandra X-ray observations
  78. GRB 231115A: Upper limits from a neutrino search with IceCube
  79. GRB 231115A: Kinder observations with Lulin observatory
  80. GRB231115A: GRANDMA Observations
  81. GRB 231115A: GOTO pre-burst limits of AT2023xvj
  82. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  83. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  84. GRB 231106A: TESS identification of candidate optical counterpart
  85. GRB 231115A: MASTER optical observations
  86. GRB 231115A (short): Glowbug gamma-ray detection
  87. GRB 231115A: Fermi Observations of a probable Magnetar Giant Flare from M82
  88. GRB 231115A: archival HST observations
  89. Integral GRB231115.65: Global MASTER-Net observations report
  90. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  91. GRB 231115A: Swift ToO observations
  92. Fermi GRB 231115A: Global MASTER-Net observations report
  93. GRB 231115A: significance of INTEGRAL localization alignment with M82
  94. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  95. GRB 231115A position consistent with M 82 galaxy
  96. GRB 231115A: Fermi GBM Final Real-time Localization
  97. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  98. GRB 231111A: Swift-BAT refined analysis
  99. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  100. LIGO/Virgo/KAGRA S231114n: Updated Sky localization

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