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"
  1. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  2. GRB 251116C: SVOM/VT optical upper limit
  3. GRB 251025B: further Mondy optical observations
  4. GRB 251111A: Mondy optical upper limit
  5. GRB 251116B: EP-FXT follow-up observation
  6. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  8. GRB 251116B: LCO optical upper limits
  9. GRB 251116C: LCO optical upper limits
  10. SVOM GRB251116C: Global MASTER-Net observations report
  11. GRB 251116C: SVOM detection of a burst
  12. GRB 251116B: SVOM detection of a burst
  13. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 251116A: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  16. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  17. GRB 251115A: Tiled Swift observations
  18. GRB 251115A: Fermi-LAT detection
  19. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  20. Fermi GRB 251115A: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  22. GRB 251115A: Fermi GBM Final Real-time Localization
  23. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  24. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  25. GRB 251113A: Glowbug gamma-ray detection
  26. GRB 251113A: AstroSat CZTI detection
  27. GRB 251114B: Fermi GBM Final Real-time Localization
  28. GRB 251112A: Swift-BAT refined analysis
  29. Konus-Wind detection of GRB 251108C
  30. Fermi trigger No 784717756: Global MASTER-Net observations report
  31. Konus-Wind detection of GRB 251103A
  32. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  33. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  34. IPN triangulation of GRB 251108C
  35. The EP-WXT trigger 01709248221 is likely a flaring star
  36. Fermi GRB 251114A: Global MASTER-Net observations report
  37. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  38. GRB 251114A: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  40. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  41. Fermi GRB 251113A: Global MASTER-Net observations report
  42. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  43. GRB 251113A: Fermi GBM Final Real-time Localization
  44. GRB 251111A: SVOM/ECLAIRs refined analysis
  45. GRB 251025B: SVOM/ECLAIRs refined analysis
  46. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  47. GRB 251112A: Swift/UVOT Upper Limits
  48. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  49. GRB 251112A: Swift-XRT refined Analysis
  50. GRB 251108C: AstroSat CZTI detection
  51. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  52. GRB 251112B: MAXI/GSC detection
  53. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  54. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  55. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  56. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  57. GRB 251108B: Glowbug gamma-ray detection
  58. Swift Trigger 1413695: a possible GRB 251112A
  59. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  60. Fermi trigger No 784621743: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  62. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  63. GRB251111A: 1.3m DFOT optical upper limit
  64. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  65. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  66. GRB 251111A: Swift-XRT afterglow detection
  67. GRB 251111A: SVOM/VT optical observations with X-band data
  68. SVOM GRB251111.42: Global MASTER-Net observations report
  69. GRB 251111A: Swift-XRT observations
  70. SVOM GRB251111.22: Global MASTER-Net observations report
  71. GRB 251111A: EP-FXT counterpart detection
  72. GRB 251013C: Chandra X-ray observations and jet break detection
  73. GRB 251111A: SVOM/VT optical observations with VHF data
  74. GRB 251111A: KAIT optical upper limit
  75. GRB 251111A: LCO optical observation
  76. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  77. GRB 251111A: SVOM detection of a soft burst
  78. GRB 251103B: Swift-BAT refined analysis
  79. GRB 251106A: Swift/UVOT Upper Limits
  80. GRB 251105B: Insight-HXMT/HE detection
  81. GRB 251106B: Insight-HXMT detection
  82. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  83. GRB 251105A: AstroSat CZTI detection
  84. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  85. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  86. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  87. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  88. GRB 251108A: Fermi GBM Final Localization Correction
  89. Fermi trigger No 784329591: Global MASTER-Net observations report
  90. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  91. Fermi trigger No 784279167: Global MASTER-Net observations report
  92. SVOM GRB251108.54: Global MASTER-Net observations report
  93. GRB 251102B: SVOM/GRM observation
  94. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  95. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  96. The EP-WXT trigger 01709248051 is likely a flaring star
  97. SVOM GRB251106.83: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  99. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  100. IPN triangulation of GRB 251105B (possible sGRB with EE)

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