Skip to main content
Retirement of GCN Classic VOEvent Brokers. 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 S231118d: Identification of a GW compact binary merger candidate
  2. GRB 231117A: GIT optical follow-up
  3. GRB 231117A: LT observations consistent with fading
  4. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  5. GRB 231117A: REM optical and NIR early-time observations
  6. GRB231117A: AGILE/MCAL analysis
  7. GRB 231117A: AKO Optical Upper Limit
  8. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  9. Swift GRB 231117A: Global MASTER-Net observations report
  10. GRB 231117A (short): Glowbug gamma-ray detection
  11. GRB 231117A: ATLAS non-detection of an optical counterpart
  12. Konus-Wind detection of GRB 231117A (short/hard)
  13. GRB 231115A : OHP/T120 optical upper limit
  14. GRB 231115A: optical observations from INAF observatories
  15. GRB 231117A : MITSuME Akeno optical upper limits
  16. GRB 231117A: AGILE detection of a bright short burst
  17. GRB 231117A: Enhanced Swift-XRT position
  18. GRB 231117A: GOTO optical upper limits
  19. GRB 231117A: AstroSat CZTI detection of a bright short burst
  20. GRB 231117A: Swift detection of a bright short burst
  21. GRB 231115A: Non-detection of radio emission with CHIME/FRB
  22. GRB 231111A: Swift/UVOT Detection
  23. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  24. GRB231115A: Liverpool Telescope imaging
  25. GRB 231115A: NuSTAR Follow-Up Observations
  26. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  27. GRB 231115A: Swift-XRT and Swift-UVOT observations
  28. Fermi GRB 231116A: Global MASTER-Net observations report
  29. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  30. GRB 231115A: AGILE/MCAL upper limits
  31. GRB 231115A: Insight-HXMT/HE detection
  32. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  33. GRB 231116A: Fermi GBM Final Real-time Localization
  34. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  35. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  36. GRB 231115A / AT2023xvj: Updated GIT analysis
  37. GRB 231115A: archival Chandra X-ray observations
  38. GRB 231115A: Upper limits from a neutrino search with IceCube
  39. GRB 231115A: Kinder observations with Lulin observatory
  40. GRB231115A: GRANDMA Observations
  41. GRB 231115A: GOTO pre-burst limits of AT2023xvj
  42. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  43. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  44. GRB 231106A: TESS identification of candidate optical counterpart
  45. GRB 231115A: MASTER optical observations
  46. GRB 231115A (short): Glowbug gamma-ray detection
  47. GRB 231115A: Fermi Observations of a probable Magnetar Giant Flare from M82
  48. GRB 231115A: archival HST observations
  49. Integral GRB231115.65: Global MASTER-Net observations report
  50. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  51. GRB 231115A: Swift ToO observations
  52. Fermi GRB 231115A: Global MASTER-Net observations report
  53. GRB 231115A: significance of INTEGRAL localization alignment with M82
  54. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  55. GRB 231115A position consistent with M 82 galaxy
  56. GRB 231115A: Fermi GBM Final Real-time Localization
  57. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  58. GRB 231111A: Swift-BAT refined analysis
  59. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  60. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  61. Fermi GRB 231114A: Global MASTER-Net observations report
  62. GRB 231113A (short): Glowbug gamma-ray detection
  63. GRB 231114A (short): Glowbug gamma-ray detection
  64. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  65. GECAM-B observation of a short burst from SGR J1555-5402
  66. GRB 231114A: Fermi GBM Final Localization
  67. LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
  68. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  69. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  70. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  71. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  72. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  74. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  75. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  76. GRB 231110A: Swift-BAT refined analysis
  77. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  78. GRB 231106A: Glowbug gamma-ray detection
  79. GRB 231111A: Xinglong-2.16m optical observations
  80. GRB 231110A: Swift-UVOT Upper Limits
  81. LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
  82. GRB 231111A: Afterglow redshift from OSIRIS+/GTC
  83. GRB 231104A: VZLUSAT-2 detection
  84. GRB 231111A: TNG tentative redshift
  85. GRB 231110A: Glowbug gamma-ray detection
  86. GRB 231110A: AstroSat CZTI detection
  87. GRB 231111A NUTTelA-TAO / BSTI Early Measurements
  88. GRB 231111A: Leavitt Observatory optical observations
  89. GRB231111A: Optical follow-up observations with Mephisto
  90. GRB 231111A: GMG observation (correction)
  91. LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
  92. GRB 231111A: GMG observation upper limit
  93. GRB 231106B: GRBAlpha detection
  94. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  95. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  96. GRB 231111A: Swift-XRT refined Analysis
  97. GRB 231111A: Mondy optical observations
  98. GRB 231111A: GECAM-C detection of a long burst (correction)
  99. GRB 231110A: GECAM-B detection (correction)
  100. GRB 231111A: Enhanced Swift-XRT position

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