Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

16155 results found.

  1. EP251118a: Continued Optical Detection with Kinder observations
  2. EP251118a: Xinglong-2.16m optical observation
  3. EP251118A: 1.3m DFOT optical afterglow detection
  4. EP251118a / GRB 251118C: SAO RAS optical observations
  5. EP251118a: Optical detection with Kinder observations
  6. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  7. EP251118a / GRB 251118C: SVOM/VT optical observation
  8. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  9. GRB 251116C: NOT optical observations
  10. GRB 251018A: FRAM-Auger optical detection
  11. EP251118A / GRB 251118C : MASTER optical counterpart observations
  12. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  13. EP251118a: FTW optical and NIR observations
  14. EP251118a: VLT near-infrared observation
  15. GRB 251116D: SVOM/GRM observation of a long GRB
  16. EP251118a: GOTO optical afterglow detection
  17. EP251118a: NOT spectroscopic redshift of z = 1.216
  18. EP251118a: preliminary result of EP-FXT follow-up observation
  19. EP251118a: NOT candidate optical counterpart
  20. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  21. GRB 251117A: SVOM/GRM observation of a short burst
  22. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  23. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  24. GRB 251116B: SVOM/VT optical upper limit
  25. EP251023a: Assy AZT-20 optical observations
  26. EP251023a: UAFO and AbAO optical observations
  27. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  28. GRB 251116C: SVOM/VT optical upper limit
  29. GRB 251025B: further Mondy optical observations
  30. GRB 251111A: Mondy optical upper limit
  31. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  32. GRB 251116B: LCO optical upper limits
  33. GRB 251116C: LCO optical upper limits
  34. GRB 251116C: SVOM detection of a burst
  35. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  36. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  37. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  38. GRB 251112A: Swift/UVOT Upper Limits
  39. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  40. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  41. GRB251111A: 1.3m DFOT optical upper limit
  42. GRB 251111A: SVOM/VT optical observations with X-band data
  43. GRB 251111A: Swift-XRT observations
  44. GRB 251111A: EP-FXT counterpart detection
  45. GRB 251111A: SVOM/VT optical observations with VHF data
  46. GRB 251111A: KAIT optical upper limit
  47. GRB 251111A: LCO optical observation
  48. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  49. GRB 251106A: Swift/UVOT Upper Limits
  50. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  51. GRB 251102B: SVOM/GRM observation
  52. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  53. GRB 251106A: Swift-XRT afterglow detection
  54. GRB 251106A: Kilonova-Catcher optical upper limit
  55. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  56. GRB 251106A: MASTER optical observations
  57. GRB 251106A: SVOM detection of a burst
  58. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  59. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  60. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 251103B: Swift/UVOT Upper Limits
  62. GRB 251104A: SVOM detection of a burst
  63. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  64. EP251102a: FTW optical and NIR observations
  65. GRB 251103A: WFST optical observations
  66. EP251102a: OHP/T193 optical observations
  67. GRB 251103A: OHP/T193 optical observations
  68. GRB 251103A: Xinglong 2.16m optical detection
  69. GRB 251103A: KAIT optical observations
  70. GRB 251103B: Nanshan/HMT optical upper limit
  71. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  72. GRB 251103B: MITSuME Akeno optical upper limits
  73. EP251102a: NIR observations with WINTER
  74. GRB 251103A: J-band detection with WINTER
  75. GRB 251103B: GROWTH-India Telescope optical upper limits
  76. GRB 251103A: Kilonova-Catcher optical afterglow detection
  77. GRB 251103A: Swift/UVOT Detection
  78. GRB 251103A: SVOM/GRM observation
  79. GRB 251103A: Swift-XRT afterglow detection
  80. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  81. EP251102a: Einstein Probe detection of a fast X-ray transient
  82. GRB 251025B: OHP/T193 optical upper limit
  83. GRB 251103A: LCO optical observation
  84. EP251102.890: COLIBRÍ optical counterpart candidate
  85. GRB 251103A: GOTO optical afterglow detection
  86. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  87. GRB 251103A: NOT spectroscopic redshift z = 0.76
  88. GRB 251103A: BOOTES-2/TELMA optical afterglow
  89. GRB 251103A: LCO optical afterglow detection
  90. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  91. GRB 251103A: NOT optical afterglow candidate
  92. GRB 251103A: SVOM detection of a bright burst
  93. GRB 251025C: SVOM/GRM observation
  94. GRB 251028A: SVOM/GRM observation
  95. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  96. GRB 251026B: LBT near-infrared observations
  97. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  98. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  99. GRB251026B: PRIME H-band upper limit
  100. GRB251025B: 3.6m DOT Optical Observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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