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"

22237 results found.

  1. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  2. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  3. Fermi GRB 250313A: Global MASTER-Net observations report
  4. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  5. EP250304a: SVOM/VT optical observation
  6. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  7. EP250302a: Chandra X-ray Detection
  8. Fermi trigger No 763509110: Global MASTER-Net observations report
  9. Fermi GRB 250312B: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  11. Swift GRB 250312A: Global MASTER-Net observations report
  12. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  13. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  14. GRB 250311A: Swift-XRT observations
  15. GRB 250309B: 1.3m DFOT Optical observations
  16. EP250311a: Global MASTER-Net observations report
  17. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  18. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  20. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  21. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  22. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  23. GRB 250309B: PRIME near-infrared detection
  24. EP250304a: Chandra detection
  25. GRB 250311A/EP250311a: TRT optical upper limit
  26. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  27. GRB 250311A: Tiled Swift observations
  28. EP250311a/GRB 250311A: EP-WXT detection
  29. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  30. GRB 250309B / AT2025dws: further SAO RAS optical observations
  31. IceCube-250309A: Upper limits from Fermi-GBM Observations
  32. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  33. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  34. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  35. GRB 250309B / IceCube-250309A: GECAM-B observations
  36. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  37. GRB 250309B / AT2025dws: SAO RAS optical observations
  38. GRB 250309B / AT2025dws: Swift-UVOT detection
  39. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  40. Fermi GRB 250309B: Global MASTER-Net observations report
  41. Fermi GRB 250309A: Global MASTER-Net observations report
  42. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  43. IceCube-250309A: No candidates from the Zwicky Transient Facility
  44. Fermi-LAT gamma-ray observations of IceCube-250309A
  45. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  46. GRB 230509B: Tiled Swift observations
  47. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  48. IceCube Alert 250309.32: Global MASTER-Net observations report
  49. EP250308a: Global MASTER-Net observations report
  50. EP250308a: GSP optical upper limit
  51. EP250308a: FTW optical and NIR upper limits
  52. EP250308a: Einstein Probe detection of an X-ray transient
  53. Fermi GRB 250307A: Global MASTER-Net observations report
  54. Konus-Wind detection of GRB 250306A
  55. EP250304a: MeerKAT detection of a possible radio counterpart
  56. EP250302a:Xinglong optical observations
  57. Fermi trigger No 762963055: Global MASTER-Net observations report
  58. Swift GRB 250306A: Global MASTER-Net observations report
  59. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  60. GRB250101A: Radio upper limits from VLA observations
  61. EP250304A: Upper limits from Fermi-GBM Observations
  62. Fermi GRB 250305A: Global MASTER-Net observations report
  63. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  64. EP250302a: Optical Observations at CrAO and SAO RAS
  65. EP 250304A: Optical counterpart detection by LCO
  66. EP250302A: 1.3m DFOT optical afterglow detection
  67. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  68. Konus-Wind detection of GRB 250222A
  69. EP250304a: REM NIR upper limits
  70. EP250302a: Mondy Continued Optical Observations
  71. EP250304a: TRT optical counterpart detection
  72. EP250304a: Global MASTER-Net observations report
  73. EP250302a: SVOM/VT optical observation
  74. EP250302a: SAO RAS optical observations
  75. EP250225a: the candidate optical counterpart is an AGN
  76. EP250302a: Kinder optical follow-up observations
  77. EP250302a: NUTTelA-TAO Early Measurments
  78. EP250302a: REM NIR upper limits
  79. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  80. EP250302a: Mondy Observations and Optical Light Curve
  81. EP250302a: VLT/MUSE optical redshift z = 1.131
  82. EP250302A: VLT near-infrared observations
  83. EP250302A: VLT/X-shooter tentative redshift
  84. EP250302a: OHP/T193 optical and spectroscopic observations
  85. EP250302a: Global MASTER-Net observations report
  86. EP250302a: Xinglong F60B optical observation
  87. EP250302a: Swift-XRT observations of a fading X-ray source
  88. EP250302a: Einstein Probe detection of an X-ray transient
  89. EP250302a: SVOM/C-GFT optical observations
  90. GRB 250226A: GRANDMA Optical Observations
  91. EP250302a: Montarrenti Observatory optical detection
  92. Fermi GRB 250302A: Global MASTER-Net observations report
  93. EP250302a: FTW optical and NIR detection
  94. EP250302a: Nanshan/HMT optical counterpart detection
  95. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  96. GRB 250225B: VLT near-infrared afterglow confirmation
  97. EP250228a: Optical observations with Kinder and Swift/UVOT
  98. Konus-Wind detection of GRB 250226A
  99. GRB 250226A: KAO Optical Upper Limit
  100. GRB 250226A: AbAO AS-32 Optical Upper Limit

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