Skip to main content
GCN at AAS 245, Legacy Circulars Address Retirement. 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').
  1. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  2. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  3. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  4. EP241109a: confirmation of a stellar flare by BOOTES-7
  5. EP241109a: EP on-board trigger and autonomous follow-up observation
  6. GRB 241108A: Swift-XRT observations
  7. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  8. EP241107A: MASTER optical observations of xray transient
  9. EP241107a: KAIT optical observations
  10. GRB 241108A: Swift ToO observations
  11. GRB 241030A: TESS observations
  12. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  13. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  14. EP241107a: Kinder optical follow-up observations
  15. GRB 241025A: radio detection with the VLA
  16. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  17. EP241107a: AKO Optical Afterglow Follow-Up Observations
  18. EP241107a: GSP detects optical counterpart
  19. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  20. GRB 241107A: SVOM/GRM detection of a short burst
  21. GRB 241105A: EP-FXT follow-up observations
  22. GRB 241105A: SVOM/GRM observation
  23. EP241107a: OHP/T193 photometric and spectroscopic observations
  24. GRB 241105a: PRIME near-infrared upper limits
  25. EP241107a: FTW Optical and NIR observations of the optical counterpart
  26. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  27. EP241107a: GIT optical observations
  28. EP241107a: Global MASTER-Net observations report
  29. EP241107a: SVOM/C-GFT optical observations
  30. EP241107a: AKO Optical Afterglow Detection
  31. GRB 241025A: LBT optical observations
  32. GRB241105A: Gemini-South Optical Afterglow Detection
  33. EP241107a: EP on-board trigger and autonomous follow-up observation
  34. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  35. GRB 241105A: Swift/UVOT Detection
  36. EP241101a: CrAO ZTSH optical observations
  37. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  38. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  39. GRB 241105A: BOOTES-7 optical detection
  40. GRB 241030A: Mondy optical observations
  41. GRB241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  42. Konus-Wind detection of GRB 241105A (short with extended emission)
  43. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  44. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  45. Konus-Wind detection of GRB 241021A
  46. GRB 241105A: SVOM/VT optical afterglow observations
  47. GRB 241105A: Swift-XRT afterglow detection
  48. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  49. GRB 241104A: Swift-XRT observations
  50. GRB 240511A: LCO upper limits
  51. GRB241104A: Fermi GBM Observation
  52. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
  53. GRB 241105A: Swift ToO observations
  54. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  55. GRB 241104A: Swift ToO observations
  56. GRB 241104A: NOT optical non-detection
  57. GRB 241105A: GOTO tentative optical counterpart candidate
  58. Fermi GRB 241105A: Global MASTER-Net observations report
  59. GRB 241104A: SVOM/VT optical candidate
  60. GRB 241105A: Fermi GBM Final Real-time Localization
  61. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  62. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  63. GRB 241104A: SVOM/GRM observation
  64. EP241104a: EP detection of GRB 241104A X-ray emission
  65. GRB 241010A: host galaxy redshift z = 0.977
  66. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  67. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  68. GRB 240821A: further radio observations with the VLA
  69. Fermi GRB 241104A: Global MASTER-Net observations report
  70. GRB 241104A: Fermi GBM Final Real-time Localization
  71. GRB 241030A: GRBAlpha detection
  72. EP241101a: EP-FXT observations update
  73. EP241103a: GIT optical upper limit
  74. EP241021a: OHP/T193 further optical observations
  75. LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
  76. Fermi trigger No 752365806: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  78. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  79. EP241103a: GOTO optical upper limit
  80. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  81. EP241101a: Possible detection of an optical counterpart with FTW
  82. EP241103a: Swift XRT detection and improved X-ray position
  83. EP241021a: continued SOAR observations
  84. EP241101a: Optical upper limits with Kinder observations
  85. EP241101a: OHP/T193 optical observations
  86. EP241103a: Gemini optical limits
  87. EP241103a: EP observation update
  88. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  89. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  90. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  91. EP241103a: GSP optical upper limit
  92. EP241103A: LCO optical observations
  93. EP241103a: Global MASTER-Net observations report
  94. EP241103a: an X-ray transient detected by Einstein Probe
  95. GRB 241030A: Rapid release of TESS data.
  96. EP241101a: Global MASTER-Net observations report
  97. GRB 241029A: GRBAlpha detection
  98. EP241101a: BOOTES-7 optical upper limit
  99. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  100. S241102cy: Identification of a GW compact binary merger candidate

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