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"

26188 results found.

  1. GRB 251128A: SVOM/GRM observation of a long burst
  2. SVOM GRB 251129A : MASTER optical counterpart detection
  3. GRB 251129A: Swift-XRT afterglow detection
  4. GRB 251129A: SVOM/VT optical fading
  5. EP251129a: Global MASTER-Net observations report
  6. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  7. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  8. GRB 251128A: Fermi GBM Observation
  9. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. GRB 251129A: SVOM detection of a burst
  11. SVOM GRB251129.11: Global MASTER-Net observations report
  12. GRB 251129A: SVOM detection of a burst
  13. GRB 251126A: Swift-BAT refined analysis
  14. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  15. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  16. Fermi GRB 251128A: Global MASTER-Net observations report
  17. GRB 251127A: Glowbug gamma-ray detection
  18. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  19. GRB 251126A: further SAO RAS optical observations
  20. GRB 251126A NUTTelA-TAO Early Measurements
  21. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  22. GRB251126A: MAO/AZT-22 optical observations
  23. GRB251126A: Continued optical observation from 1.3m DFOT
  24. GRB 251126A: Swift/UVOT Detection
  25. GRB 251126A: Mondy and SAO RAS optical observations
  26. GRB 251126A: Swift-XRT refined Analysis
  27. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  28. GRB 251126A: NOT optical observations
  29. GRB 251126A: 1.3m DFOT optical afterglow detection
  30. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  31. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  32. Fermi GRB 251127A: Global MASTER-Net observations report
  33. GRB 251126A: Enhanced Swift-XRT position
  34. GRB 251126A: Kilonova-Catcher optical afterglow detection
  35. GRB 251126A: Nanshan/HMT optical afterglow detection
  36. Swift GRB 251126A: Global MASTER-Net observations report
  37. GRB 251121A: Fermi GBM Observation
  38. GRB 251126A: GIT discovery of the likely optical afterglow
  39. GRB 251126A: Swift detection of a burst
  40. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  41. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  42. EP251124b: NOT r- and z-band optical upper limits
  43. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  44. Fermi GRB 251125B: Global MASTER-Net observations report
  45. EP251124b: Global MASTER-Net observations report
  46. EP251124b: EP-WXT detection of a fast X-ray transient
  47. EP251124a: Xinglong GWAC-F60A optical observation
  48. Fermi GRB 251125A: Global MASTER-Net observations report
  49. EP251124a: NOT r- and z-band optical upper limits
  50. EP251124a: Global MASTER-Net observations report
  51. EP251124a: Swift-XRT observations
  52. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  53. EP251124a: Optical upper limit with Kinder observations
  54. Fermi GRB 251124a: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  56. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  57. EP251124a: GROWTH-India Telescope optical upper limits
  58. EP251124a: Einstein Probe detection of an X-ray transient
  59. GRB 251116C: Swift-XRT confirmation of fading
  60. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  61. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  62. EP251118A: 3.6m DOT optical afterglow detection
  63. GRB 251122A / EP251122a: EP-FXT counterpart detection
  64. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  65. GRB 251122A / EP251122a: WFST optical observations
  66. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  67. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  68. GRB 251122A / EP251122a: LCO optical upper limits
  69. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  70. EP251122a: Global MASTER-Net observations report
  71. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  72. GRB 251122A / EP251122a: SVOM detection of a long burst
  73. EP251122a: Einstein Probe detection of an X-ray transient
  74. EP251118a: Continued Optical Detection with Kinder observations
  75. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  76. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  77. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  78. EP251118a: Xinglong-2.16m optical observation
  79. GRB 251115A: Fermi GBM Observation
  80. Fermi trigger No 785388351: Global MASTER-Net observations report
  81. EP251118A: 1.3m DFOT optical afterglow detection
  82. GRB 251118A: Swift/UVOT Detection
  83. EP251118a / GRB 251118C: SAO RAS optical observations
  84. GRB 251118A: Glowbug gamma-ray detection
  85. GRB 251118A: Fermi GBM Observation
  86. GRB 251118A: Swift-XRT afterglow detection
  87. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  88. EP251118a: Optical detection with Kinder observations
  89. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  90. GRB 251118A: NuSTAR detection of bright prompt emission
  91. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  92. GRB 251116C: NOT optical observations
  93. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  94. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  95. GRB 251117A: Swift-XRT observations
  96. EP251118A / GRB 251118C : MASTER optical counterpart observations
  97. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  98. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  99. EP251118a: VLT near-infrared observation
  100. GRB 251116D: SVOM/GRM observation of a long GRB

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