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"

43058 results found.

  1. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  2. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  3. GRB 250626A: Fermi GBM Final Real-time Localization
  4. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  5. GRB 250625A: SVOM/C-GFT upper limit in early phase
  6. GRB 250625A: GECAM-B detection
  7. GRB 250625A: Swift/UVOT Upper Limits
  8. GRB 250625A: ABObservatory afterglow detection
  9. GRB 250625A: OHP/T193 optical detection
  10. GRB 250625A: COLIBRÍ optical observations
  11. GRB 250625A: Fermi-LAT detection
  12. GRB 250625A: Swift-XRT refined Analysis
  13. GRB 250625A: JinShan optical observations
  14. GRB250625A: Fermi GBM Observation
  15. Swift GRB 250625A: Global MASTER-Net observations report
  16. GRB 250625A: NOT z-band upper limit
  17. GRB 250625A: SVOM/VT optical confirmation
  18. GRB 250620B: Fermi GBM Observation
  19. GRB 250625A: SAO RAS possible optical afterglow
  20. GRB 250625A: Enhanced Swift-XRT position
  21. Fermi GRB 250625A: Global MASTER-Net observations report
  22. GRB 250625A: Swift detection of a burst
  23. GRB 250625A: Fermi GBM Final Real-time Localization
  24. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  25. GRB 250620A: AstroSat CZTI detection
  26. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  27. GRB 241018A: Maidanak optical observations
  28. GRB 250620C: AstroSat CZTI detection
  29. Fermi GRB 250624A: Global MASTER-Net observations report
  30. GRB 250624A: Fermi GBM Final Real-time Localization
  31. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  32. Fermi GRB 250623A: Global MASTER-Net observations report
  33. GRB 250623A: Fermi GBM Final Real-time Localization
  34. GRB 250521A: VZLUSAT-2 detection
  35. GRB 250617B: Swift-BAT refined analysis
  36. Fermi trigger No 772190032: Global MASTER-Net observations report
  37. Konus-Wind detection of GRB 250620C
  38. IPN triangulation of GRB 250620C (long/bright)
  39. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  40. GRB 250620C: SVOM/GRM observation
  41. GRB 250620A: SVOM/GRM observation of a short burst
  42. GRB250620A: Fermi GBM Observation
  43. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  44. Fermi GRB 250621A: Global MASTER-Net observations report
  45. GRB 250619B: Fermi GBM Observation
  46. GRB 250621A: Fermi GBM Final Real-time Localization
  47. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  48. GRB250620C: Fermi GBM Observation
  49. GRB 250506A - SVOM/ECLAIRs Refined analysis
  50. The EP-WXT trigger 01709179071 is likely a flaring star
  51. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  52. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  53. GRB 250620C: Fermi GBM Final Real-time Localization
  54. Fermi trigger No 772128434: Global MASTER-Net observations report
  55. GRB 250620B: Fermi GBM Final Real-time Localization
  56. GRB 250620A: Fermi GBM Final Real-time Localization
  57. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  58. GRB 250617B: Nickel telescope optical observations
  59. GRB 250619B: Fermi GBM Final Real-time Localization
  60. Fermi trigger No 772058337: Global MASTER-Net observations report
  61. GRB 250615A: Kilonova-Catcher optical upper limits
  62. GRB 250619A: Fermi GBM Final Real-time Localization
  63. GRB 250617B: Assy AZT-20 Optical Observations
  64. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  65. Fermi GRB 250617A: Global MASTER-Net observations report
  66. GRB 250615A/EP250615a: FTW optical and NIR observations
  67. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  68. GRB 250617B: Swift/UVOT Detection
  69. GRB 250617B: Kilonova-Catcher optical afterglow detection
  70. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  71. GRB 250617B: COLIBRÍ optical observations
  72. GRB 250617B: NOT NIR observations of the afterglow
  73. GRB 250617B: Swift-XRT refined Analysis
  74. GRB 250617B: SVOM/VT optical observation
  75. GRB 250617B: NUTTelA-TAO early time optical observations
  76. Fermi trigger No 771886893: Global MASTER-Net observations report
  77. Swift GRB 250617B: Global MASTER-Net observations report
  78. GRB 250617B: GOTO optical upper limit
  79. GRB 250617B: Enhanced Swift-XRT position
  80. GRB 250617B: Fermi GBM Observation
  81. GRB 250615A: Swift-BAT refined analysis
  82. The EP-WXT trigger 01709178990 is likely a flaring star
  83. GRB 250617B: Fermi GBM Final Localization
  84. GRB 250617B: Ondrejov D50 optical afterglow detection
  85. GRB 250617B: SAO RAS optical observations
  86. GRB 250617B: Swift detection of a burst with an optical counterpart
  87. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  88. GRB 250617A: Fermi GBM Final Real-time Localization
  89. IPN triangulation of GRB 250612C (short/hard)
  90. EP#01709178975: Swift-XRT counterpart detection
  91. EP-WXT trigger 01709178975: GOTO optical upper limit
  92. The EP-WXT trigger 01709178975 is likely a flaring star
  93. Konus-Wind detection of GRB 250615A / EP250615a
  94. GRB 250615A / EP250615a: AstroSat CZTI detection
  95. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  96. GRB 250615A: COLIBRÍ optical upper limit
  97. GRB 250615A: DDOTI Optical Upper Limit
  98. GRB 250615A: Swift/UVOT Upper Limits
  99. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  100. GRB 250615A: Swift-XRT refined Analysis

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