Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

37279 results found.

  1. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  2. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  3. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  4. GRB 250317B: SVOM detection of a burst
  5. GRB 250316A: Fermi GBM Observation
  6. GRB 250316A: Swift-XRT observations
  7. GRB 250317A: Fermi GBM Final Real-time Localization
  8. Fermi GRB 250316A: Global MASTER-Net observations report
  9. GRB 250314A: SVOM/GRM analysis
  10. GRB 250316A: Swift ToO observations
  11. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  12. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  13. GRB 250316A: Fermi GBM Final Real-time Localization
  14. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  15. GRB 250314A: EP-FXT afterglow detection
  16. GRB 250314A: Swift/UVOT Upper Limits
  17. GRB 250312B: GRBAlpha detection
  18. GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
  19. GRB 250314A: Swift XRT Detection
  20. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  21. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  22. SVOM/MXT upper limit on GRB 250314A
  23. GRB 250314A: SVOM/VT upper limit
  24. GRB 250314A: NOT near-infrared candidate counterpart
  25. GRB 250313A: Fermi GBM Detection
  26. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  27. GRB 250312B: Fermi GBM Observation
  28. GRB 250313A: Swift-XRT observations
  29. Konus-Wind detection of GRB 250313A
  30. Konus-Wind detection of GRB 250308A
  31. GRB 250314A: SVOM detection of a burst
  32. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  33. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  34. GRB 250313A: SVOM/GRM observation of a bright long burst
  35. GRB 250313A: AstroSat CZTI detection of a bright long burst
  36. GRB 250313A: Fermi-LAT detection
  37. GRB 250313A: Swift ToO observations
  38. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  39. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  40. Fermi GRB 250313A: Global MASTER-Net observations report
  41. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  42. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  43. GRB 250313A: Fermi GBM Final Real-time Localization
  44. EP250311a/GRB 250311A: EP-FXT follow-up observation
  45. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  46. GRB 250312A: Swift-XRT refined Analysis
  47. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  48. Fermi GRB 250312B: Global MASTER-Net observations report
  49. GRB 250312A: Enhanced Swift-XRT position
  50. GRB 250312B: Fermi GBM Final Localization
  51. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  52. GRB 250226B: Fermi GBM Observation
  53. Swift GRB 250312A: Global MASTER-Net observations report
  54. GRB 250302A: Fermi GBM Observation
  55. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  56. GRB 250312A: Swift detection of a burst
  57. GRB 241213A: VIRT Optical Upper Limit
  58. GRB 241228A: VIRT Optical Upper Limit
  59. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  60. GRB 250223B: Fermi GBM Observation
  61. GRB 250311A: Swift-XRT observations
  62. GRB 250228A: Fermi GBM Observation
  63. GRB 250309B: 1.3m DFOT Optical observations
  64. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  65. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  66. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  67. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  68. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  69. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  70. GRB 250309B: PRIME near-infrared detection
  71. GRB 250225B: Swift-BAT refined analysis
  72. GRB 250311A/EP250311a: TRT optical upper limit
  73. GRB 250311A: Tiled Swift observations
  74. EP250311a/GRB 250311A: EP-WXT detection
  75. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  76. GRB 250311B: SVOM detection of a burst
  77. GRB 250309B: SVOM/VT optical observation
  78. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  79. GRB 250309B / AT2025dws: further SAO RAS optical observations
  80. IceCube-250309A: Upper limits from Fermi-GBM Observations
  81. EP250308a: 1.6m Mephisto optical upper limits
  82. Konus-Wind detection of GRB 250309B
  83. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  84. IPN triangulation of GRB 250308A (short)
  85. IPN triangulation of GRB 250309B
  86. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  87. GRB 250309B: Swift-XRT refined Analysis
  88. GRB 250309B / IceCube-250309A: GECAM-B observations
  89. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  90. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  91. GRB 250309B / AT2025dws: SAO RAS optical observations
  92. GRB 250309B / AT2025dws: Swift-UVOT detection
  93. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  94. GRB 250309B: Fermi GBM Observation
  95. Fermi GRB 250309B: Global MASTER-Net observations report
  96. Fermi GRB 250309A: Global MASTER-Net observations report
  97. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  98. IceCube-250309A: No candidates from the Zwicky Transient Facility
  99. Fermi-LAT gamma-ray observations of IceCube-250309A
  100. GRB 250308A: SVOM/GRM detection of QPO in the tail emission

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