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"

38681 results found.

  1. The EP-WXT trigger 01709248403 is likely a flaring star
  2. GRB 251118A: NuSTAR detection of bright prompt emission
  3. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  4. GRB 251116C: NOT optical observations
  5. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  6. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  7. GRB 251117A: Swift-XRT observations
  8. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  9. Konus-Wind detection of GRB 251118C (EP251118a)
  10. The EP-WXT trigger 01709248388 is likely a flaring star
  11. GRB 251117A: Insight-HXMT/HE detection
  12. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  13. EP251118a: VLT near-infrared observation
  14. GRB 251116D: SVOM/GRM observation of a long GRB
  15. EP251118a: GOTO optical afterglow detection
  16. GRB 251119A: SVOM detection of a possible burst
  17. EP251118a: NOT spectroscopic redshift of z = 1.216
  18. EP251118a: preliminary result of EP-FXT follow-up observation
  19. GRB 251118A: Fermi-LAT detection
  20. EP251118a: NOT candidate optical counterpart
  21. GRB 251118A: Swift ToO observations
  22. EP251118a: Einstein Probe detected of a fast X-ray transient
  23. GRB 251118B: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  25. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  26. GRB 251118A: Fermi GBM Final Real-time Localization
  27. GRB 251116C: SVOM/ECLAIRs refined analysis
  28. GRB 251116B: SVOM/ECLAIRs refined analysis
  29. GRB 251117A: AstroSat CZTI detection
  30. GRB 251114B: Insight-HXMT/HE detection
  31. GRB 251114B: GECAM-B detection of a short burst
  32. GRB 251117A: Fermi GBM observation
  33. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  34. GRB 251116D: Insight-HXMT/HE detection
  35. GRB 251115A: Swift-XRT observations
  36. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  37. GRB 251117A: SVOM/GRM observation of a short burst
  38. GRB 251117A: Tiled Swift observations
  39. GRB 251117A: Fermi-LAT detection
  40. GRB 251116C: Swift/BAT arcminute localization of a burst
  41. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  42. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  43. GRB 251116B: SVOM/VT optical upper limit
  44. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  45. GRB 251116C: Swift-XRT observations
  46. GRB 251117A: Fermi GBM Final Localization Correction
  47. GRB 251116D: Glowbug gamma-ray detection
  48. EP251023a: Assy AZT-20 optical observations
  49. EP251023a: UAFO and AbAO optical observations
  50. GRB 251116D: AstroSat CZTI detection
  51. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  52. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  53. GRB 251116C: SVOM/VT optical upper limit
  54. GRB 251025B: further Mondy optical observations
  55. GRB 251111A: Mondy optical upper limit
  56. GRB 251116B: EP-FXT follow-up observation
  57. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  58. GRB 251116B: LCO optical upper limits
  59. GRB 251116C: LCO optical upper limits
  60. SVOM GRB251116C: Global MASTER-Net observations report
  61. GRB 251116C: SVOM detection of a burst
  62. GRB 251116B: SVOM detection of a burst
  63. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 251116A: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  66. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  67. GRB 251115A: Tiled Swift observations
  68. GRB 251115A: Fermi-LAT detection
  69. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  70. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  71. GRB 251115A: Fermi GBM Final Real-time Localization
  72. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  73. GRB 251113A: Glowbug gamma-ray detection
  74. GRB 251113A: AstroSat CZTI detection
  75. GRB 251114B: Fermi GBM Final Real-time Localization
  76. Konus-Wind detection of GRB 251108C
  77. Konus-Wind detection of GRB 251103A
  78. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  79. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  80. IPN triangulation of GRB 251108C
  81. The EP-WXT trigger 01709248221 is likely a flaring star
  82. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  83. GRB 251114A: Fermi GBM Final Real-time Localization
  84. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  85. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  86. GRB 251113A: Fermi GBM Final Real-time Localization
  87. GRB 251111A: SVOM/ECLAIRs refined analysis
  88. GRB 251025B: SVOM/ECLAIRs refined analysis
  89. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  90. GRB 251112A: Swift/UVOT Upper Limits
  91. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  92. GRB 251112A: Swift-XRT refined Analysis
  93. GRB 251108C: AstroSat CZTI detection
  94. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  95. GRB 251112B: MAXI/GSC detection
  96. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  97. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  98. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  99. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  100. GRB 251108B: Glowbug gamma-ray detection

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