Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32752 results found.

  1. Fermi GRB 251113A: Global MASTER-Net observations report
  2. GRB 251111A: SVOM/ECLAIRs refined analysis
  3. GRB 251025B: SVOM/ECLAIRs refined analysis
  4. GRB 251112A: Swift/UVOT Upper Limits
  5. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  6. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  7. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  8. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  9. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  10. GRB251111A: 1.3m DFOT optical upper limit
  11. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  12. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  13. GRB 251111A: SVOM/VT optical observations with X-band data
  14. GRB 251111A: Swift-XRT observations
  15. GRB 251111A: EP-FXT counterpart detection
  16. GRB 251013C: Chandra X-ray observations and jet break detection
  17. GRB 251111A: SVOM/VT optical observations with VHF data
  18. GRB 251111A: KAIT optical upper limit
  19. GRB 251111A: LCO optical observation
  20. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  21. GRB 251103B: Swift-BAT refined analysis
  22. GRB 251106A: Swift/UVOT Upper Limits
  23. GRB 251105B: Insight-HXMT/HE detection
  24. GRB 251106B: Insight-HXMT detection
  25. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  26. GRB 251105A: AstroSat CZTI detection
  27. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  28. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  29. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  30. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  31. GRB 251102B: SVOM/GRM observation
  32. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  33. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  34. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  35. IPN triangulation of GRB 251105B (possible sGRB with EE)
  36. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  37. GRB 251106A: Swift-XRT afterglow detection
  38. GRB 251106A: Kilonova-Catcher optical upper limit
  39. Fermi GBM Sub-Threshold Detection of GRB 251106A
  40. GRB 251106A: Swift/BAT arcminute localization of a burst
  41. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  42. GRB 251106A: MASTER optical observations
  43. GRB 251103B: AstroSat CZTI detection
  44. GRB 251025C: TERI Gamma-ray detection
  45. GRB 251016B: TERI Gamma-ray detection
  46. GRB 251016A: TERI Gamma-ray detection of a short burst
  47. GRB 250920C: TERI Gamma-ray detection
  48. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  49. GRB 251105A: Fermi GBM Observation
  50. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  53. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  54. Fermi GBM Sub-Threshold Detection of GRB 251105B
  55. GRB 251103B: Swift/UVOT Upper Limits
  56. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  57. Fermi GRB 251105A: Global MASTER-Net observations report
  58. GRB 251103B: Fermi GBM observation
  59. GRB 251028A: Insight-HXMT/HE detection
  60. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  61. EP251102a: FTW optical and NIR observations
  62. GRB 251103A: WFST optical observations
  63. EP251102a: update of EP-FXT follow-up observation
  64. EP251102a: OHP/T193 optical observations
  65. GRB 251103A: OHP/T193 optical observations
  66. GRB 251103A: Xinglong 2.16m optical detection
  67. GRB 251103A: Insight-HXMT detection
  68. GRB 251103A: KAIT optical observations
  69. GRB 251103B: Nanshan/HMT optical upper limit
  70. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  71. GRB 251103B: MITSuME Akeno optical upper limits
  72. Fermi GRB 251103A: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  74. EP251102a: NIR observations with WINTER
  75. GRB 251103A: J-band detection with WINTER
  76. Swift GRB 251103B: Global MASTER-Net observations report
  77. GRB 251103B: GROWTH-India Telescope optical upper limits
  78. GRB 251103A: Kilonova-Catcher optical afterglow detection
  79. GRB 251103A: Swift/UVOT Detection
  80. GRB 251103A: Fermi GBM Observation
  81. GRB 251103A: SVOM/GRM observation
  82. GRB 251103A: Swift-XRT afterglow detection
  83. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  84. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  85. EP251102a: Einstein Probe detection of a fast X-ray transient
  86. GRB 251025B: OHP/T193 optical upper limit
  87. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  88. GRB 251103A: LCO optical observation
  89. GRB 251103A: GOTO optical afterglow detection
  90. GRB 251102A: AstroSat CZTI detection
  91. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  92. GRB 251103A: NOT spectroscopic redshift z = 0.76
  93. GRB 251103A: LCO optical afterglow detection
  94. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  95. GRB 251103A: NOT optical afterglow candidate
  96. Fermi GRB 251102A: Global MASTER-Net observations report
  97. GRB 251031A: Fermi GBM Observation
  98. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  99. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  100. Konus-Wind detection of GRB 251028A

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