Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

44625 results found.

  1. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 250901A: SVOM/VT optical afterglow with VHF data
  3. GRB 250901A: Swift-XRT afterglow detection
  4. EP250901a: Swift-XRT observations
  5. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  6. GRB 250901A: LCO optical upper limit
  7. EP250827b: Swift observations of AT 2025wkm
  8. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  9. EP250827b: Gemini Spectroscopy of AT 2025wkm
  10. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  11. EP250831a: NOT optical observations and tentative afterglow candidate
  12. EP250827b: FTW Observations of AT 2025wkm
  13. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  14. GRB 250901A: SVOM detection of a burst
  15. GRB 250831B: SVOM/GRM observation
  16. GRB 250830C: Insight-HXMT detection
  17. EP250901a: Mephisto optical upper limits
  18. GRB 250830C: GECAM-B detection
  19. EP250901a: Global MASTER-Net observations report
  20. GRB 250830C: AstroSat CZTI detection of a long burst
  21. EP250901a: Einstein Probe detection of an X-ray transient
  22. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  23. EP250831a: EP-FXT follow-up observation
  24. EP250831a: Swift-XRT observations
  25. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  26. IceCube Alert 250831.75: Global MASTER-Net observations report
  27. EP250831a: Global MASTER-Net observations report
  28. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  29. EP250831a: EP-WXT detection of a fast X-ray transient
  30. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  31. GRB 250831A: Swift-XRT counterpart detection
  32. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRB 250831A: SVOM/VT upper limit with VHF data
  34. GRB 250831A: SVOM detection of a soft burst
  35. GRB 250830B: Swift-XRT observations
  36. EP250830a: Global MASTER-Net observations report
  37. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  38. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  39. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  40. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  41. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  42. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  43. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  44. GRB 250830B: Swift ToO observations
  45. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  46. GRB 250830B: MAXI/GSC detection
  47. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  48. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  49. The EP-WXT trigger 01709200994 is likely a flaring star
  50. GRB 250828B: Swift-BAT refined analysis
  51. EP250821a: SOAR observations
  52. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  53. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  54. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  55. GRB 250808B: SVOM detection of a burst through offline search
  56. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  57. EP250828a: Optical counterpart detection with Kinder observations
  58. EP250828a: Liverpool Telescope upper limits
  59. Swift GRB 250828B: Global MASTER-Net observations report
  60. EP250828a: Global MASTER-Net observations report
  61. EP-WXT trigger 01709200800 : KAIT optical observations
  62. EP250828a: KAIT optical upper limit
  63. EP250827a: Swift/UVOT Detection
  64. EP250828a: NOT optical counterpart confirmation
  65. EP250828a: SVOM/VT optical candidate
  66. EP250828a: Seimei/TriCCS optical counterpart detection
  67. GRB 250828B: Swift detection of a burst
  68. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  69. EP250828a: Optical upper limit with Kinder observations
  70. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  71. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  72. EP250827a: LCO observations show fading optical counterpart
  73. GRB 250828A: Fermi GBM Final Localization
  74. EP250828a: Einstein Probe detection of an X-ray transient
  75. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  76. GRID detection of GRB 250824A
  77. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  78. EP250827A: VLT/X-shooter redshift confirmation
  79. Fermi GRB 250827A: Global MASTER-Net observations report
  80. EP250827a: confirmation of optical rebrightening with LCO
  81. EP250827a: GOTO observation of the optical afterglow
  82. GRB 250826A: SVOM/GRM observation
  83. GRB 250827A: Fermi GBM Final Real-time Localization
  84. EP250827A: An optical rebrightening was detected by LCO.
  85. EP250827a: Swift-XRT counterpart detection
  86. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  87. The EP-WXT trigger 01709200800 is likely a flaring star
  88. EP250827a: TRT optical observations
  89. EP250827a: BOOTES-7 early optical dectection
  90. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  91. EP250827a: Gemini-South redshift z = 1.613
  92. EP250827a: Global MASTER-Net observations report
  93. EP250827a: Las Cumbres independent detection of the optical counterpart
  94. EP250827a: Gemini-South optical counterpart detection
  95. EP250827a: Einstein Probe detection of an X-ray transient
  96. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  97. Fermi GRB 250826A: Global MASTER-Net observations report
  98. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  99. EP250821a: Gemini GMOS Redshift Confirmation
  100. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz

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