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"

26511 results found.

  1. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  2. Fermi trigger No 784279167: Global MASTER-Net observations report
  3. SVOM GRB251108.54: Global MASTER-Net observations report
  4. GRB 251102B: SVOM/GRM observation
  5. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  6. SVOM GRB251106.83: Global MASTER-Net observations report
  7. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  8. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  9. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  10. GRB 251106A: Swift-XRT afterglow detection
  11. GRB 251106A: Kilonova-Catcher optical upper limit
  12. Fermi GBM Sub-Threshold Detection of GRB 251106A
  13. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  14. GRB 251106A: MASTER optical observations
  15. GRB 251025C: TERI Gamma-ray detection
  16. GRB 251016B: TERI Gamma-ray detection
  17. GRB 251016A: TERI Gamma-ray detection of a short burst
  18. GRB 250920C: TERI Gamma-ray detection
  19. Fermi trigger No 784034269: Global MASTER-Net observations report
  20. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  21. GRB 251105A: Fermi GBM Observation
  22. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  23. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. Fermi GBM Sub-Threshold Detection of GRB 251105B
  25. GRB 251103B: Swift/UVOT Upper Limits
  26. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  27. GRB 251103B: Fermi GBM observation
  28. GRB 251103A: WFST optical observations
  29. GRB 251103A: OHP/T193 optical observations
  30. GRB 251103A: Xinglong 2.16m optical detection
  31. GRB 251103A: KAIT optical observations
  32. GRB 251103B: Nanshan/HMT optical upper limit
  33. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  34. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  35. GRB 251103B: MITSuME Akeno optical upper limits
  36. GRB 251103B: Swift-XRT refined Analysis
  37. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  38. EP251102a: NIR observations with WINTER
  39. GRB 251103A: J-band detection with WINTER
  40. GRB 251103B: GROWTH-India Telescope optical upper limits
  41. GRB 251103A: Kilonova-Catcher optical afterglow detection
  42. GRB 251103B: Enhanced Swift-XRT position
  43. GRB 251103B: Swift detection of a burst
  44. GRB 251103A: Swift/UVOT Detection
  45. GRB 251103A: Fermi GBM Observation
  46. GRB 251103A: Swift-XRT afterglow detection
  47. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  48. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. EP251102a: Einstein Probe detection of a fast X-ray transient
  50. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  51. GRB 251103A: LCO optical observation
  52. EP251102.890: COLIBRÍ optical counterpart candidate
  53. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  54. GRB 251103A: LCO optical afterglow detection
  55. GRB 251103A: NOT optical afterglow candidate
  56. GRB 251031A: Fermi GBM Observation
  57. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  58. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  60. GRB 251025C: SVOM/GRM observation
  61. GRB 251028A: SVOM/GRM observation
  62. GRB 251028A: Fermi GBM Observation
  63. GRB 251022A: Swift-XRT confirmation of fading
  64. GRB 250926A: VZLUSAT-2 detection
  65. GRB 251026B: Fermi GBM Observation
  66. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  67. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  68. GRB 251028B: Glowbug gamma-ray detection
  69. GRB 251028A: Glowbug gamma-ray detection
  70. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  71. GRB251026B: PRIME H-band upper limit
  72. GRB251025B: 3.6m DOT Optical Observations
  73. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  74. GRB 251028A: MAXI/GSC detection
  75. SVOM trigger sb25102702/GRB 251027A is not a GRB
  76. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  78. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  79. GRB 251025C: Glowbug gamma-ray detection
  80. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  81. GRB 251027A: Swift-XRT observations
  82. EP251027.145: COLIBRÍ optical upper limits
  83. GRB 251022A: SVOM/GRM observation
  84. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  85. GRB 251027A: LCO optical upper limit
  86. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  88. GRB 251023B / EP251023b: Mondy optical upper limit
  89. GRB 251017A: INASAN-Kislovodsk optical observations
  90. GRB 251026A: Mondy optical upper limit
  91. GRB 251025B: Mondy optical observations
  92. GRB 251025B: Kilonova-Catcher optical afterglow detection
  93. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  94. GRB 251027A: SVOM detection of a faint burst
  95. EP251023a: Mondy optical observations
  96. GRB 251025B: MAO/AZT-22 optical observations
  97. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  98. Fermi GRB 251025C: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  100. GRB 251026A: Swift-XRT observations

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